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Gluing 2 single sided boards to make a double sided board.

Gluing 2 single sided boards to make a double sided board.

2015-07-05 by James

Double sided boards as we all know can be a bit of a pain, the biggest problem is getting that precise alignment between sides correct so that when you drill in the center of your pad on one side, it comes out in the center of the pad on the other (and not, as is not uncommon, breaking out, and probably messing up the trace, or a trace nearby...).  Especially if your only able to expose/imprint artwork one side at a time.

Even more frustrating when one side comes out perfect in part of the process (eg, developing) and the other side is too flawed to be useful, meaning you get to start from scratch again.

So, the thought randomly occurred to me today, if you could prepare, expose, etch, drill the two sides of a double sided board completely separately, and join them up at the end of the process, it would make getting precise alignment of those sides almost a non-issue, assuming you can drill even roughly vertically and hit the center of the holes it's just a matter of lining up the holes you drilled on each side.  And also means that the success or failure of each side is independent of the other.

Of course, it does double the drilling, but that's the easy bit really.

This is also of course more or less how multi layer PCBs are made by fabricators, a stackup of already prepared pcb layers and resin impregnated sheets.

Single sided laminate at 0.8mm thick (and you can get down to 0.5mm) is available out of China for cheap.

Eg:

Has anybody done this... am I reinventing a triangular wheel here, is it doomed to failure?  Suggestions on suitable adhesive... maybe just spray on contact adhesive might work, it's a pretty big flat contact area.


Re: [Homebrew_PCBs] Gluing 2 single sided boards to make a double sided board.

2015-07-05 by Petar Delic

Hi,

It is not worth the effort.

The best way of doing it is just drilling 3 referent holes (that should be placed in advanced in layout) and using them for mask alignment for both side of double sided boards.

I tried to make multilayer boards and I almost done it (I have diy CNC and heating press with 20 tons for gluing cores and prepregs and chemical process for copper plating holes....).

It is interesting that my CNC has 0.01 mm precision but holes positions weren't precise (let say that the worst precision was 0.1 mm). I later discovered that I can use some aluminum sheet to enhance hole positions ...

Prepreg is a uncured laminate that acts as a glue (but in my case I manage to get 20 years old prepreg.... and actually it was working where FR4 prepreg faced the FR4 core, despite 20 years old the it glued well, but where prepreg glued to copper that was weak.... and I had problems - micro air bubbles where prepreg meets the copper and when I tried to solder the board in the oven it slightly delaminates ....).

I had 3 major problems: weak connection between prepreg and copper (I tried to make the copper surface rough by micro etching but that didn't work), weak connection between copper that plates the hole and the hole wall (I didn't find out the stuff that dissolve FR4 and make surface rough for better plating, well... I didn't find commonly available stuff for dissolving FR4).

Other than that my multilayer boards prototypes worked even at 6 Gb/s speed (I made some FPGA transceivers small boards....).

Thanks,
Petar 
 
 



On 07/05/2015 07:13 AM, James bitsyboffin@... [Homebrew_PCBs] wrote:
 
Double sided boards as we all know can be a bit of a pain, the biggest problem is getting that precise alignment between sides correct so that when you drill in the center of your pad on one side, it comes out in the center of the pad on the other (and not, as is not uncommon, breaking out, and probably messing up the trace, or a trace nearby...).  Especially if your only able to expose/imprint artwork one side at a time.

Even more frustrating when one side comes out perfect in part of the process (eg, developing) and the other side is too flawed to be useful, meaning you get to start from scratch again.

So, the thought randomly occurred to me today, if you could prepare, expose, etch, drill the two sides of a double sided board completely separately, and join them up at the end of the process, it would make getting precise alignment of those sides almost a non-issue, assuming you can drill even roughly vertically and hit the center of the holes it's just a matter of lining up the holes you drilled on each side.  And also means that the success or failure of each side is independent of the other.

Of course, it does double the drilling, but that's the easy bit really.

This is also of course more or less how multi layer PCBs are made by fabricators, a stackup of already prepared pcb layers and resin impregnated sheets.

Single sided laminate at 0.8mm thick (and you can get down to 0.5mm) is available out of China for cheap.

Eg:

Has anybody done this... am I reinventing a triangular wheel here, is it doomed to failure?  Suggestions on suitable adhesive... maybe just spray on contact adhesive might work, it's a pretty big flat contact area.



RE: [Homebrew_PCBs] Gluing 2 single sided boards to make a double sided board.

2015-07-05 by Tony Smith

The drilled holes will never line up properly, it’s a fundamental property of universe.

 

When gluing use a bright light underneath so you can see both sets of tracks, and use something like the mounting hole outlines to align them.

 

Tony

 

 

 

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
Sent: Sunday, 5 July 2015 3:14 PM
To: Homebrew PCBs
Subject: [Homebrew_PCBs] Gluing 2 single sided boards to make a double sided board.

 




Double sided boards as we all know can be a bit of a pain, the biggest problem is getting that precise alignment between sides correct so that when you drill in the center of your pad on one side, it comes out in the center of the pad on the other (and not, as is not uncommon, breaking out, and probably messing up the trace, or a trace nearby...).  Especially if your only able to expose/imprint artwork one side at a time.

 

Even more frustrating when one side comes out perfect in part of the process (eg, developing) and the other side is too flawed to be useful, meaning you get to start from scratch again.

 

So, the thought randomly occurred to me today, if you could prepare, expose, etch, drill the two sides of a double sided board completely separately, and join them up at the end of the process, it would make getting precise alignment of those sides almost a non-issue, assuming you can drill even roughly vertically and hit the center of the holes it's just a matter of lining up the holes you drilled on each side.  And also means that the success or failure of each side is independent of the other.

 

Of course, it does double the drilling, but that's the easy bit really.

 

This is also of course more or less how multi layer PCBs are made by fabricators, a stackup of already prepared pcb layers and resin impregnated sheets.

 

Single sided laminate at 0.8mm thick (and you can get down to 0.5mm) is available out of China for cheap.

 

Eg:

 

Has anybody done this... am I reinventing a triangular wheel here, is it doomed to failure?  Suggestions on suitable adhesive... maybe just spray on contact adhesive might work, it's a pretty big flat contact area.

 

 




RE: [Homebrew_PCBs] Gluing 2 single sided boards to make a double sided board.

2015-07-05 by heimbach@...

It'd be interesting if your thought works.


Some ideas than might help you with the alignment of the holes:
- Increase the size of the holes and the space around it so that you
have greater tolerance
- Add two more holes in two edges of your board for centering. Drill
those in both boards (so in total 4), glue your boards together and line
them with a nail or similar (while the glue isn't dried).
After the glue has dried you should then be able to drill all the other
holes with a very good precision.


Maybe this helps you.


Simon




Am 05.07.2015 13:14, schrieb 'Tony Smith' ajsmith1968@...
[Homebrew_PCBs]:
> The drilled holes will never line up properly, it’s a fundamental
> property of universe.
>
> When gluing use a bright light underneath so you can see both sets of
> tracks, and use something like the mounting hole outlines to align
> them.
>
> Tony
>
> FROM: Homebrew_PCBs@yahoogroups.com
> [mailto:Homebrew_PCBs@yahoogroups.com]
> SENT: Sunday, 5 July 2015 3:14 PM
> TO: Homebrew PCBs
> SUBJECT: [Homebrew_PCBs] Gluing 2 single sided boards to make a double
> sided board.
>
> Double sided boards as we all know can be a bit of a pain, the biggest
> problem is getting that precise alignment between sides correct so
> that when you drill in the center of your pad on one side, it comes
> out in the center of the pad on the other (and not, as is not
> uncommon, breaking out, and probably messing up the trace, or a trace
> nearby...). Especially if your only able to expose/imprint artwork one
> side at a time.
>
> Even more frustrating when one side comes out perfect in part of the
> process (eg, developing) and the other side is too flawed to be
> useful, meaning you get to start from scratch again.
>
> So, the thought randomly occurred to me today, if you could prepare,
> expose, etch, drill the two sides of a double sided board completely
> separately, and join them up at the end of the process, it would make
> getting precise alignment of those sides almost a non-issue, assuming
> you can drill even roughly vertically and hit the center of the holes
> it's just a matter of lining up the holes you drilled on each side.
> And also means that the success or failure of each side is independent
> of the other.
>
> Of course, it does double the drilling, but that's the easy bit
> really.
>
> This is also of course more or less how multi layer PCBs are made by
> fabricators, a stackup of already prepared pcb layers and resin
> impregnated sheets.
>
> Single sided laminate at 0.8mm thick (and you can get down to 0.5mm)
> is available out of China for cheap.
>
> Eg:
>
> http://item.taobao.com/item.htm?spm=a1z10.5-c.w4002-1192550948.12.TIEXsq&id=35870048695
> [1]
>
> http://item.taobao.com/item.htm?spm=a230r.1.14.4.VdTsRT&id=21105435798&ns=1&abbucket=3#detail
> [2]
>
> Has anybody done this... am I reinventing a triangular wheel here, is
> it doomed to failure? Suggestions on suitable adhesive... maybe just
> spray on contact adhesive might work, it's a pretty big flat contact
> area.

Re: Gluing 2 single sided boards to make a double sided board.

2015-07-05 by arvidj@...

If we make an assumption that each board is etched accurately then maybe 2 appropriately placed alignment holes could be drilled [maybe at the diagonal corners of the print], then Tony's visual inspection along with something like a toothpick thru the holes to help align them when they are glued together and finally drill the rest of the holes thru both boards at one time.

Less drilling and possibly better chance of the holes being in the correct place on both sides.

Arvid  

Re: [Homebrew_PCBs] Gluing 2 single sided boards to make a double sided board.

2015-07-05 by Mat Smith

I must say, the idea of gluing together two single-sided PCBs to make a double-sided PCB seems excessively tedious.

Perhaps it's because I don't really agree with you that the most difficult part of a double-sided PCB is lining the holes / tracks up.

When I first started, I thought lining up the holes would be the most difficult part. But I've never had anything but great success in this area.

The most difficult part for me has been knowing how long to iron and the time it takes to peel. To get excellent results (really fine / straight edges to tracks and toner that adheres amazingly well) I iron for 35-40 minutes... and the longer I iron the harder it is to remove the paper. This to me seems excessive but anything else results in having to use a lot of sharpie and boards that don't look as nice.

May I ask exactly how you are lining the layers up?

Here's my process. Here I overexplain it, but it doesn't actually take more than 3-5 minutes.

I cut the two pieces of paper, one piece slightly smaller than the other to allow for better grip when I tape them together.

I hold the two pieces of paper up against a worklight and ensure the designs line-up perfectly, then fold a tiny piece of masking tape over the two pieces of paper, in the middle of one of the edges. I then hold them up to the light to ensure they are still lined up, and add another small piece of tape onto the middle of another of the edges. If for some reason the papers became misaligned it's then easy to remove a single tab of tape and do it again.

Finally, repeat the process for the third side, check the alignment by shining the worklight through the papers, then run tape lenghtways down all three sides.

Drop the board in (which has been prepared obsessively with metal wool and white spirit / acetone) and check there that the effect of separating the papers with the 1.6mm FR4 hasn't misaligned the papers. Almost every time I've dropped the PCB in, it hasn't caused any misalignment. Always check the papers lie flat.

When the PCB is in, seal the final 4th side with a line of masking tape. It doesn't matter if the PCB rattles around, in fact it's better to make the paper a fair bit larger than the PCB that drops into the envelope you have created.

You then line up the PCB so it fits to the design just before you iron (using a worklight again).

The above hasn't failed for me ever, and it's pretty quick to do despite my over-explanation!

Thanks

Mat
On Sun, 5 Jul 2015 at 12:14, 'Tony Smith' ajsmith1968@... [Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:
 

The drilled holes will never line up properly, it’s a fundamental property of universe.

 

When gluing use a bright light underneath so you can see both sets of tracks, and use something like the mounting hole outlines to align them.

 

Tony

 

 

 

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
Sent: Sunday, 5 July 2015 3:14 PM
To: Homebrew PCBs
Subject: [Homebrew_PCBs] Gluing 2 single sided boards to make a double sided board.

 




Double sided boards as we all know can be a bit of a pain, the biggest problem is getting that precise alignment between sides correct so that when you drill in the center of your pad on one side, it comes out in the center of the pad on the other (and not, as is not uncommon, breaking out, and probably messing up the trace, or a trace nearby...).  Especially if your only able to expose/imprint artwork one side at a time.

 

Even more frustrating when one side comes out perfect in part of the process (eg, developing) and the other side is too flawed to be useful, meaning you get to start from scratch again.

 

So, the thought randomly occurred to me today, if you could prepare, expose, etch, drill the two sides of a double sided board completely separately, and join them up at the end of the process, it would make getting precise alignment of those sides almost a non-issue, assuming you can drill even roughly vertically and hit the center of the holes it's just a matter of lining up the holes you drilled on each side.  And also means that the success or failure of each side is independent of the other.

 

Of course, it does double the drilling, but that's the easy bit really.

 

This is also of course more or less how multi layer PCBs are made by fabricators, a stackup of already prepared pcb layers and resin impregnated sheets.

 

Single sided laminate at 0.8mm thick (and you can get down to 0.5mm) is available out of China for cheap.

 

Eg:

 

Has anybody done this... am I reinventing a triangular wheel here, is it doomed to failure?  Suggestions on suitable adhesive... maybe just spray on contact adhesive might work, it's a pretty big flat contact area.

 

 




Re: [Homebrew_PCBs] Gluing 2 single sided boards to make a double sided board.

2015-07-05 by Harvey White

On Sun, 5 Jul 2015 17:13:52 +1200, you wrote:

>Double sided boards as we all know can be a bit of a pain, the biggest
>problem is getting that precise alignment between sides correct so that
>when you drill in the center of your pad on one side, it comes out in the
>center of the pad on the other (and not, as is not uncommon, breaking out,
>and probably messing up the trace, or a trace nearby...). Especially if
>your only able to expose/imprint artwork one side at a time.

Even, then, you have to be certain that the top and bottom sources for
the artwork are properly aligned. Easier for photographic use, but
not perhaps for toner transfer

>
>Even more frustrating when one side comes out perfect in part of the
>process (eg, developing) and the other side is too flawed to be useful,
>meaning you get to start from scratch again.

Agreed.
>
>So, the thought randomly occurred to me today, if you could prepare,
>expose, etch, drill the two sides of a double sided board completely
>separately, and join them up at the end of the process, it would make
>getting precise alignment of those sides almost a non-issue, assuming you
>can drill even roughly vertically and hit the center of the holes it's just
>a matter of lining up the holes you drilled on each side. And also means
>that the success or failure of each side is independent of the other.
>

Exactly, but the drilling of the alignment holes is critical. More
later.

>Of course, it does double the drilling, but that's the easy bit really.

It doesn't if you align the boards first then drill.
>
>This is also of course more or less how multi layer PCBs are made by
>fabricators, a stackup of already prepared pcb layers and resin impregnated
>sheets.
>
however, they have cnc stuff that is far more accurate than the
average home fill-in-blank here.....
>Single sided laminate at 0.8mm thick (and you can get down to 0.5mm) is
>available out of China for cheap.
>
>Eg:
>http://item.taobao.com/item.htm?spm=a1z10.5-c.w4002-1192550948.12.TIEXsq&id=35870048695
>http://item.taobao.com/item.htm?spm=a230r.1.14.4.VdTsRT&id=21105435798&ns=1&abbucket=3#detail
>
>Has anybody done this... am I reinventing a triangular wheel here, is it
>doomed to failure? Suggestions on suitable adhesive... maybe just spray on
>contact adhesive might work, it's a pretty big flat contact area.

er... no, no contact adhesive ever, once it contacts, it grabs, and
you cannot adjust the alignment.


Short form of what I do:

1) create alignment holes (generally an unnamed via), Use 3 in an
asymmetric layout so that you can't misalign the board.

2) etch

3) drill holes for pins. I use map pins, which are short, moderately
fat, and I have a drill that fits them properly. You don't want
wobble.

4) cover the board surface except for the alignment holes with masking
tape, keeps epoxy off the board tracks.

5) mix epoxy, the 1 hour type is preferred. If you use 5 minute, then
you almost have to mix a new batch each board.

6) spread thinly on one board surface, poke pins through, align boards

7) press boards together and tape edges together. Masking tape is
fine.

8) place boards between two ceramic tiles (cheap is best) for 24 hours

9) remove tape, trim, and drill.

I use an upside down drill press with a TV camera for alignment. You
want the holes as accurately placed as possible. I can get within
about 0.002 or so (rough estimate) with this setup.

Harvey

Re: [Homebrew_PCBs] Gluing 2 single sided boards to make a double sided board.

2015-07-05 by Harvey White

On Sun, 05 Jul 2015 13:41:48 +0000, you wrote:

>I must say, the idea of gluing together two single-sided PCBs to make a
>double-sided PCB seems excessively tedious.
>
>
>Perhaps it's because I don't really agree with you that the most difficult
>part of a double-sided PCB is lining the holes / tracks up.
>

Was for me, but I do 0.019 holes (or so, a #76 or so drill), 144 pin
FPGA chips, 0.5mm spacing, 0.010 traces. YMMV on that.

>
>When I first started, I thought lining up the holes would be the most
>difficult part. But I've never had anything but great success in this area.
>
>
>The most difficult part for me has been knowing how long to iron and the
>time it takes to peel. To get excellent results (really fine / straight
>edges to tracks and toner that adheres amazingly well) I iron for 35-40
>minutes... and the longer I iron the harder it is to remove the paper. This
>to me seems excessive but anything else results in having to use a lot of
>sharpie and boards that don't look as nice.

I use Pulsar paper, which is not as transparent as what you may be
using. aligning top and bottom is not that easy, since the paper is a
good 60# paper, about the consistency of a paperback book cover.

>
>
>May I ask exactly how you are lining the layers up?
>
>
>Here's my process. Here I overexplain it, but it doesn't actually take more
>than 3-5 minutes.
>
>
>I cut the two pieces of paper, one piece slightly smaller than the other to
>allow for better grip when I tape them together.
>
>
>I hold the two pieces of paper up against a worklight and ensure the
>designs line-up perfectly, then fold a tiny piece of masking tape over the
>two pieces of paper, in the middle of one of the edges. I then hold them up
>to the light to ensure they are still lined up, and add another small piece
>of tape onto the middle of another of the edges. If for some reason the
>papers became misaligned it's then easy to remove a single tab of tape and
>do it again.

I had tried this with pin pokes through the paper to create holes.
Accuracy of drilling is critical, of course.

>
>
>Finally, repeat the process for the third side, check the alignment by
>shining the worklight through the papers, then run tape lenghtways down all
>three sides.
>
>
>Drop the board in (which has been prepared obsessively with metal wool and
>white spirit / acetone) and check there that the effect of separating the
>papers with the 1.6mm FR4 hasn't misaligned the papers. Almost every time
>I've dropped the PCB in, it hasn't caused any misalignment. Always check
>the papers lie flat.
>
>
>When the PCB is in, seal the final 4th side with a line of masking tape. It
>doesn't matter if the PCB rattles around, in fact it's better to make the
>paper a fair bit larger than the PCB that drops into the envelope you have
>created.
>
>
>You then line up the PCB so it fits to the design just before you iron
>(using a worklight again).
>
>
>The above hasn't failed for me ever, and it's pretty quick to do despite my
>over-explanation!

With the Pulsar paper, I don't need to iron that much. I also had
pattern damage when feeding a double-sided board through the laminator
*if* I was trying to do one side at a time on double sided board.

Harvey

>
>
>Thanks
>
>
>Mat
>On Sun, 5 Jul 2015 at 12:14, 'Tony Smith' ajsmith1968@...
>[Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:
>
>
>>
>>
>> The drilled holes will never line up properly, it’s a fundamental property
>> of universe.
>>
>>
>>
>> When gluing use a bright light underneath so you can see both sets of
>> tracks, and use something like the mounting hole outlines to align them.
>>
>>
>>
>> Tony
>>
>>
>>
>>
>>
>>
>>
>> *From:* Homebrew_PCBs@yahoogroups.com [mailto:
>> Homebrew_PCBs@yahoogroups.com]
>> *Sent:* Sunday, 5 July 2015 3:14 PM
>> *To:* Homebrew PCBs
>> *Subject:* [Homebrew_PCBs] Gluing 2 single sided boards to make a double
>> sided board.
>>
>>
>>
>>
>>
>>
>> Double sided boards as we all know can be a bit of a pain, the biggest
>> problem is getting that precise alignment between sides correct so that
>> when you drill in the center of your pad on one side, it comes out in the
>> center of the pad on the other (and not, as is not uncommon, breaking out,
>> and probably messing up the trace, or a trace nearby...). Especially if
>> your only able to expose/imprint artwork one side at a time.
>>
>>
>>
>> Even more frustrating when one side comes out perfect in part of the
>> process (eg, developing) and the other side is too flawed to be useful,
>> meaning you get to start from scratch again.
>>
>>
>
>>
>> So, the thought randomly occurred to me today, if you could prepare,
>> expose, etch, drill the two sides of a double sided board completely
>> separately, and join them up at the end of the process, it would make
>> getting precise alignment of those sides almost a non-issue, assuming you
>> can drill even roughly vertically and hit the center of the holes it's just
>> a matter of lining up the holes you drilled on each side. And also means
>> that the success or failure of each side is independent of the other.
>>
>>
>>
>> Of course, it does double the drilling, but that's the easy bit really.
>>
>
>>
>>
>> This is also of course more or less how multi layer PCBs are made by
>
>> fabricators, a stackup of already prepared pcb layers and resin impregnated
>> sheets.
>>
>>
>>
>> Single sided laminate at 0.8mm thick (and you can get down to 0.5mm) is
>> available out of China for cheap.
>>
>>
>>
>> Eg:
>>
>>
>> http://item.taobao.com/item.htm?spm=a1z10.5-c.w4002-1192550948.12.TIEXsq&id=35870048695
>>
>>
>> http://item.taobao.com/item.htm?spm=a230r.1.14.4.VdTsRT&id=21105435798&ns=1&abbucket=3#detail
>>
>>
>>
>> Has anybody done this... am I reinventing a triangular wheel here, is it
>> doomed to failure? Suggestions on suitable adhesive... maybe just spray on
>> contact adhesive might work, it's a pretty big flat contact area.
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>

Re: [Homebrew_PCBs] Gluing 2 single sided boards to make a double sided board.

2015-07-05 by synth

making a pocket is the easiest way to do this.  what is explained below works very well and usually the only issue one might run into is the printing heating the PnP blue slightly different causing the layout to be slightly off.  kinda like shrinkydink.  


On Jul 5, 2015, at 8:41 AM, Mat Smith hazymat@... [Homebrew_PCBs] wrote:

 

I must say, the idea of gluing together two single-sided PCBs to make a double-sided PCB seems excessively tedious.

Perhaps it's because I don't really agree with you that the most difficult part of a double-sided PCB is lining the holes / tracks up.

When I first started, I thought lining up the holes would be the most difficult part. But I've never had anything but great success in this area.

The most difficult part for me has been knowing how long to iron and the time it takes to peel. To get excellent results (really fine / straight edges to tracks and toner that adheres amazingly well) I iron for 35-40 minutes... and the longer I iron the harder it is to remove the paper. This to me seems excessive but anything else results in having to use a lot of sharpie and boards that don't look as nice.

May I ask exactly how you are lining the layers up?

Here's my process. Here I overexplain it, but it doesn't actually take more than 3-5 minutes.

I cut the two pieces of paper, one piece slightly smaller than the other to allow for better grip when I tape them together.

I hold the two pieces of paper up against a worklight and ensure the designs line-up perfectly, then fold a tiny piece of masking tape over the two pieces of paper, in the middle of one of the edges. I then hold them up to the light to ensure they are still lined up, and add another small piece of tape onto the middle of another of the edges. If for some reason the papers became misaligned it's then easy to remove a single tab of tape and do it again.

Finally, repeat the process for the third side, check the alignment by shining the worklight through the papers, then run tape lenghtways down all three sides.

Drop the board in (which has been prepared obsessively with metal wool and white spirit / acetone) and check there that the effect of separating the papers with the 1.6mm FR4 hasn't misaligned the papers. Almost every time I've dropped the PCB in, it hasn't caused any misalignment. Always check the papers lie flat.

When the PCB is in, seal the final 4th side with a line of masking tape. It doesn't matter if the PCB rattles around, in fact it's better to make the paper a fair bit larger than the PCB that drops into the envelope you have created.

You then line up the PCB so it fits to the design just before you iron (using a worklight again).

The above hasn't failed for me ever, and it's pretty quick to do despite my over-explanation!

Thanks

Mat
On Sun, 5 Jul 2015 at 12:14, 'Tony Smith' ajsmith1968@... [Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:
 

The drilled holes will never line up properly, it’s a fundamental property of universe.

 

When gluing use a bright light underneath so you can see both sets of tracks, and use something like the mounting hole outlines to align them.

 

Tony

 

 

 

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
Sent: Sunday, 5 July 2015 3:14 PM
To: Homebrew PCBs
Subject: [Homebrew_PCBs] Gluing 2 single sided boards to make a double sided board.



 




Double sided boards as we all know can be a bit of a pain, the biggest problem is getting that precise alignment between sides correct so that when you drill in the center of your pad on one side, it comes out in the center of the pad on the other (and not, as is not uncommon, breaking out, and probably messing up the trace, or a trace nearby...).  Especially if your only able to expose/imprint artwork one side at a time.

 

Even more frustrating when one side comes out perfect in part of the process (eg, developing) and the other side is too flawed to be useful, meaning you get to start from scratch again.

 

So, the thought randomly occurred to me today, if you could prepare, expose, etch, drill the two sides of a double sided board completely separately, and join them up at the end of the process, it would make getting precise alignment of those sides almost a non-issue, assuming you can drill even roughly vertically and hit the center of the holes it's just a matter of lining up the holes you drilled on each side.  And also means that the success or failure of each side is independent of the other.

 

Of course, it does double the drilling, but that's the easy bit really.

 

This is also of course more or less how multi layer PCBs are made by fabricators, a stackup of already prepared pcb layers and resin impregnated sheets.

 

Single sided laminate at 0.8mm thick (and you can get down to 0.5mm) is available out of China for cheap.

 

Eg:

 

Has anybody done this... am I reinventing a triangular wheel here, is it doomed to failure?  Suggestions on suitable adhesive... maybe just spray on contact adhesive might work, it's a pretty big flat contact area.

 

 









Re: [Homebrew_PCBs] Gluing 2 single sided boards to make a double sided board.

2015-07-05 by James

Interesting ideas everybody, to so summarise everybody's comments

1. it does work
2. use alignment holes and pins as a jig to align the two sides
3. use epoxy
4. drill the actual holes after the glue-up
5. it might not be any easier in the long run :-)

I might grab some 0.8mm and give it a go.

I use PCB rivets for vias, so my thought was to use these as the alignment pins, they are a tight fit in 0.8mm holes.

> May I ask exactly how you are lining the layers up?

I use photo exposure (dry film resist) on a single sided UV box, when doing double sided, I use the inside corner of a plastic set-square as a stop agains the same corner on the bottom and top artwork, and push the appropriate PCB corner into the square for each side.  It works oookay for the most part, but if you don't have two perfectly perpendicular sides on your PCB so there is no "wobble" when you push it into the square's inside corner, it's easy to get a slight rotational misalignment.  

That said, my may well be that I can't drill perpendicular hand-held to save my life, doesn't take much of an angle to break out of a 0.2 or 0.3mm annular ring on the backside when being perfectly centred on the front side.  Perhaps I should just get a mini drill press and rig up some camera magnification on it :-)


On Mon, Jul 6, 2015 at 8:36 AM, Harvey White madyn@... [Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:
 

On Sun, 05 Jul 2015 13:41:48 +0000, you wrote:

>I must say, the idea of gluing together two single-sided PCBs to make a
>double-sided PCB seems excessively tedious.
>
>
>Perhaps it's because I don't really agree with you that the most difficult
>part of a double-sided PCB is lining the holes / tracks up.
>

 Was for me, but I do 0.019 holes (or so, a #76 or so drill), 144 pin
FPGA chips, 0.5mm spacing, 0.010 traces. YMMV on that.

>
>When I first started, I thought lining up the holes would be the most
>difficult part. But I've never had anything but great success in this area.
>
>
>The most difficult part for me has been knowing how long to iron and the
>time it takes to peel. To get excellent results (really fine / straight
>edges to tracks and toner that adheres amazingly well) I iron for 35-40
>minutes... and the longer I iron the harder it is to remove the paper. This
>to me seems excessive but anything else results in having to use a lot of
>sharpie and boards that don't look as nice.

 I use Pulsar paper, which is not as transparent as what you may be
using. aligning top and bottom is not that easy, since the paper is a
good 60# paper, about the consistency of a paperback book cover.

>
>
>May I ask exactly how you are lining the layers up?
>
>
>Here's my process. Here I overexplain it, but it doesn't actually take more
>than 3-5 minutes.
>
>
>I cut the two pieces of paper, one piece slightly smaller than the other to
>allow for better grip when I tape them together.
>
>
>I hold the two pieces of paper up against a worklight and ensure the
>designs line-up perfectly, then fold a tiny piece of masking tape over the
>two pieces of paper, in the middle of one of the edges. I then hold them up
>to the light to ensure they are still lined up, and add another small piece
>of tape onto the middle of another of the edges. If for some reason the
>papers became misaligned it's then easy to remove a single tab of tape and
>do it again.

 I had tried this with pin pokes through the paper to create holes.
Accuracy of drilling is critical, of course.

>
>
>Finally, repeat the process for the third side, check the alignment by
>shining the worklight through the papers, then run tape lenghtways down all
>three sides.
>
>
>Drop the board in (which has been prepared obsessively with metal wool and
>white spirit / acetone) and check there that the effect of separating the
>papers with the 1.6mm FR4 hasn't misaligned the papers. Almost every time
>I've dropped the PCB in, it hasn't caused any misalignment. Always check
>the papers lie flat.
>
>
>When the PCB is in, seal the final 4th side with a line of masking tape. It
>doesn't matter if the PCB rattles around, in fact it's better to make the
>paper a fair bit larger than the PCB that drops into the envelope you have
>created.
>
>
>You then line up the PCB so it fits to the design just before you iron
>(using a worklight again).
>
>
>The above hasn't failed for me ever, and it's pretty quick to do despite my
>over-explanation!

 With the Pulsar paper, I don't need to iron that much. I also had
pattern damage when feeding a double-sided board through the laminator
*if* I was trying to do one side at a time on double sided board.

Harvey

>
>
>Thanks
>
>
>Mat
>On Sun, 5 Jul 2015 at 12:14, 'Tony Smith' ajsmith1968@...
>[Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:
>
>
>>
>>
>> The drilled holes will never line up properly, it’s a fundamental property
>> of universe.
>>
>>
>>
>> When gluing use a bright light underneath so you can see both sets of
>> tracks, and use something like the mounting hole outlines to align them.
>>
>>
>>
>> Tony
>>
>>
>>
>>
>>
>>
>>
 >> *From:* Homebrew_PCBs@yahoogroups.com [mailto:
>> Homebrew_PCBs@yahoogroups.com]
>> *Sent:* Sunday, 5 July 2015 3:14 PM
>> *To:* Homebrew PCBs
>> *Subject:* [Homebrew_PCBs] Gluing 2 single sided boards to make a double


>> sided board.
>>
>>
>>
>>
>>
>>
>> Double sided boards as we all know can be a bit of a pain, the biggest
>> problem is getting that precise alignment between sides correct so that
>> when you drill in the center of your pad on one side, it comes out in the
>> center of the pad on the other (and not, as is not uncommon, breaking out,
>> and probably messing up the trace, or a trace nearby...). Especially if
>> your only able to expose/imprint artwork one side at a time.
>>
>>
>>
>> Even more frustrating when one side comes out perfect in part of the
>> process (eg, developing) and the other side is too flawed to be useful,
>> meaning you get to start from scratch again.
>>
>>
>
>>
>> So, the thought randomly occurred to me today, if you could prepare,
>> expose, etch, drill the two sides of a double sided board completely
>> separately, and join them up at the end of the process, it would make
>> getting precise alignment of those sides almost a non-issue, assuming you
>> can drill even roughly vertically and hit the center of the holes it's just
>> a matter of lining up the holes you drilled on each side. And also means
>> that the success or failure of each side is independent of the other.
>>
>>
>>
>> Of course, it does double the drilling, but that's the easy bit really.
>>
>
>>
>>
>> This is also of course more or less how multi layer PCBs are made by
>
>> fabricators, a stackup of already prepared pcb layers and resin impregnated
>> sheets.
>>
>>
>>
>> Single sided laminate at 0.8mm thick (and you can get down to 0.5mm) is
>> available out of China for cheap.
>>
>>
>>
>> Eg:
>>
>>
>> http://item.taobao.com/item.htm?spm=a1z10.5-c.w4002-1192550948.12.TIEXsq&id=35870048695
>>
>>
>> http://item.taobao.com/item.htm?spm=a230r.1.14.4.VdTsRT&id=21105435798&ns=1&abbucket=3#detail
>>
>>
>>
>> Has anybody done this... am I reinventing a triangular wheel here, is it
>> doomed to failure? Suggestions on suitable adhesive... maybe just spray on
>> contact adhesive might work, it's a pretty big flat contact area.
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>


Re: [Homebrew_PCBs] Gluing 2 single sided boards to make a double sided board.

2015-07-06 by Harvey White

On Mon, 6 Jul 2015 11:59:44 +1200, you wrote:

>Interesting ideas everybody, to so summarise everybody's comments
>
>1. it does work
>2. use alignment holes and pins as a jig to align the two sides
>3. use epoxy
>4. drill the actual holes after the glue-up
>5. it might not be any easier in the long run :-)
>
>I might grab some 0.8mm and give it a go.
>
>I use PCB rivets for vias, so my thought was to use these as the alignment
>pins, they are a tight fit in 0.8mm holes.

I used to use pcb rivets, but they took too much space. For my boards
now, I use #26 wire and lace the vias together, solder both sides, cut
them free, and that works. not pretty, but it works.
>
>> May I ask exactly how you are lining the layers up?
>
>I use photo exposure (dry film resist) on a single sided UV box, when doing
>double sided, I use the inside corner of a plastic set-square as a stop
>agains the same corner on the bottom and top artwork, and push the
>appropriate PCB corner into the square for each side. It works oookay for
>the most part, but if you don't have two perfectly perpendicular sides on
>your PCB so there is no "wobble" when you push it into the square's inside
>corner, it's easy to get a slight rotational misalignment.
>

then the thing would be to drill the alignment holes first, and use
those holes to position the board and the master negative/positive.

with a dual sided alignment setup, you actually could do a decent two
layer board in one exposure. You'd want an alignment jig with
accurately positioned (and decently sized) pins.

>That said, my may well be that I can't drill perpendicular hand-held to
>save my life, doesn't take much of an angle to break out of a 0.2 or 0.3mm
>annular ring on the backside when being perfectly centred on the front
>side. Perhaps I should just get a mini drill press and rig up some camera
>magnification on it :-)
>

please.... <grin>

I tried a dremel, bad runout, drill bit wobbles because of the collet

I used a proxxon, the 12 volt version works fine, although I have
both.

on the other hand (please check other posts under my name for
details), I've got a linear bearing table, one axis, stepper drive,
and a TV camera for the drilling rig.

It does make a difference. I was trying to drill holes accurately
with a drill press but viewing from the side at an extreme angle....
Doesn't work well.

I also tried thin pins, but the press in map pins are thick enough
that they generally don't wobble much. The alignment holes in this
are absolutely critical.

Harvey

>
>On Mon, Jul 6, 2015 at 8:36 AM, Harvey White madyn@...
>[Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:
>
>>
>>
>> On Sun, 05 Jul 2015 13:41:48 +0000, you wrote:
>>
>> >I must say, the idea of gluing together two single-sided PCBs to make a
>> >double-sided PCB seems excessively tedious.
>> >
>> >
>> >Perhaps it's because I don't really agree with you that the most difficult
>> >part of a double-sided PCB is lining the holes / tracks up.
>> >
>>
>> Was for me, but I do 0.019 holes (or so, a #76 or so drill), 144 pin
>> FPGA chips, 0.5mm spacing, 0.010 traces. YMMV on that.
>>
>> >
>> >When I first started, I thought lining up the holes would be the most
>> >difficult part. But I've never had anything but great success in this
>> area.
>> >
>> >
>> >The most difficult part for me has been knowing how long to iron and the
>> >time it takes to peel. To get excellent results (really fine / straight
>> >edges to tracks and toner that adheres amazingly well) I iron for 35-40
>> >minutes... and the longer I iron the harder it is to remove the paper.
>> This
>> >to me seems excessive but anything else results in having to use a lot of
>> >sharpie and boards that don't look as nice.
>>
>> I use Pulsar paper, which is not as transparent as what you may be
>> using. aligning top and bottom is not that easy, since the paper is a
>> good 60# paper, about the consistency of a paperback book cover.
>>
>> >
>> >
>> >May I ask exactly how you are lining the layers up?
>> >
>> >
>> >Here's my process. Here I overexplain it, but it doesn't actually take
>> more
>> >than 3-5 minutes.
>> >
>> >
>> >I cut the two pieces of paper, one piece slightly smaller than the other
>> to
>> >allow for better grip when I tape them together.
>> >
>> >
>> >I hold the two pieces of paper up against a worklight and ensure the
>> >designs line-up perfectly, then fold a tiny piece of masking tape over the
>> >two pieces of paper, in the middle of one of the edges. I then hold them
>> up
>> >to the light to ensure they are still lined up, and add another small
>> piece
>> >of tape onto the middle of another of the edges. If for some reason the
>> >papers became misaligned it's then easy to remove a single tab of tape and
>> >do it again.
>>
>> I had tried this with pin pokes through the paper to create holes.
>> Accuracy of drilling is critical, of course.
>>
>> >
>> >
>> >Finally, repeat the process for the third side, check the alignment by
>> >shining the worklight through the papers, then run tape lenghtways down
>> all
>> >three sides.
>> >
>> >
>> >Drop the board in (which has been prepared obsessively with metal wool and
>> >white spirit / acetone) and check there that the effect of separating the
>> >papers with the 1.6mm FR4 hasn't misaligned the papers. Almost every time
>> >I've dropped the PCB in, it hasn't caused any misalignment. Always check
>> >the papers lie flat.
>> >
>> >
>> >When the PCB is in, seal the final 4th side with a line of masking tape.
>> It
>> >doesn't matter if the PCB rattles around, in fact it's better to make the
>> >paper a fair bit larger than the PCB that drops into the envelope you have
>> >created.
>> >
>> >
>> >You then line up the PCB so it fits to the design just before you iron
>> >(using a worklight again).
>> >
>> >
>> >The above hasn't failed for me ever, and it's pretty quick to do despite
>> my
>> >over-explanation!
>>
>> With the Pulsar paper, I don't need to iron that much. I also had
>> pattern damage when feeding a double-sided board through the laminator
>> *if* I was trying to do one side at a time on double sided board.
>>
>> Harvey
>>
>> >
>> >
>> >Thanks
>> >
>> >
>> >Mat
>> >On Sun, 5 Jul 2015 at 12:14, 'Tony Smith' ajsmith1968@...
>> >[Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:
>> >
>> >
>> >>
>> >>
>> >> The drilled holes will never line up properly, it’s a fundamental
>> property
>> >> of universe.
>> >>
>> >>
>> >>
>> >> When gluing use a bright light underneath so you can see both sets of
>> >> tracks, and use something like the mounting hole outlines to align them.
>> >>
>> >>
>> >>
>> >> Tony
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >> *From:* Homebrew_PCBs@yahoogroups.com [mailto:
>> >> Homebrew_PCBs@yahoogroups.com]
>> >> *Sent:* Sunday, 5 July 2015 3:14 PM
>> >> *To:* Homebrew PCBs
>> >> *Subject:* [Homebrew_PCBs] Gluing 2 single sided boards to make a double
>>
>> >> sided board.
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >> Double sided boards as we all know can be a bit of a pain, the biggest
>> >> problem is getting that precise alignment between sides correct so that
>> >> when you drill in the center of your pad on one side, it comes out in
>> the
>> >> center of the pad on the other (and not, as is not uncommon, breaking
>> out,
>> >> and probably messing up the trace, or a trace nearby...). Especially if
>> >> your only able to expose/imprint artwork one side at a time.
>> >>
>> >>
>> >>
>> >> Even more frustrating when one side comes out perfect in part of the
>> >> process (eg, developing) and the other side is too flawed to be useful,
>> >> meaning you get to start from scratch again.
>> >>
>> >>
>> >
>> >>
>> >> So, the thought randomly occurred to me today, if you could prepare,
>> >> expose, etch, drill the two sides of a double sided board completely
>> >> separately, and join them up at the end of the process, it would make
>> >> getting precise alignment of those sides almost a non-issue, assuming
>> you
>> >> can drill even roughly vertically and hit the center of the holes it's
>> just
>> >> a matter of lining up the holes you drilled on each side. And also means
>> >> that the success or failure of each side is independent of the other.
>> >>
>> >>
>> >>
>> >> Of course, it does double the drilling, but that's the easy bit really.
>> >>
>> >
>> >>
>> >>
>> >> This is also of course more or less how multi layer PCBs are made by
>> >
>> >> fabricators, a stackup of already prepared pcb layers and resin
>> impregnated
>> >> sheets.
>> >>
>> >>
>> >>
>> >> Single sided laminate at 0.8mm thick (and you can get down to 0.5mm) is
>> >> available out of China for cheap.
>> >>
>> >>
>> >>
>> >> Eg:
>> >>
>> >>
>> >>
>> http://item.taobao.com/item.htm?spm=a1z10.5-c.w4002-1192550948.12.TIEXsq&id=35870048695
>> >>
>> >>
>> >>
>> http://item.taobao.com/item.htm?spm=a230r.1.14.4.VdTsRT&id=21105435798&ns=1&abbucket=3#detail
>> >>
>> >>
>> >>
>> >> Has anybody done this... am I reinventing a triangular wheel here, is it
>> >> doomed to failure? Suggestions on suitable adhesive... maybe just spray
>> on
>> >> contact adhesive might work, it's a pretty big flat contact area.
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>>
>>
>>

Re: [Homebrew_PCBs] Gluing 2 single sided boards to make a double sided board.

2015-07-06 by <n0tt1@...>


I would be more inclined to drill just two holes on opposite
sides of a double-sided board before exposure/etching so
that alinement would be a lot easier.
 
Best,
Charlie
 
On Sun, 5 Jul 2015 17:13:52 +1200 "James bitsyboffin@... [Homebrew_PCBs]" <Homebrew_PCBs@yahoogroups.com> writes:
 
 
Double sided boards as we all know can be a bit of a pain, the biggest problem is getting that precise alignment between sides correct so that when you drill in the center of your pad on one side, it comes out in the center of the pad on the other (and not, as is not uncommon, breaking out, and probably messing up the trace, or a trace nearby...).  Especially if your only able to expose/imprint artwork one side at a time.
 

Even more frustrating when one side comes out perfect in part of the process (eg, developing) and the other side is too flawed to be useful, meaning you get to start from scratch again.
 

So, the thought randomly occurred to me today, if you could prepare, expose, etch, drill the two sides of a double sided board completely separately, and join them up at the end of the process, it would make getting precise alignment of those sides almost a non-issue, assuming you can drill even roughly vertically and hit the center of the holes it's just a matter of lining up the holes you drilled on each side.  And also means that the success or failure of each side is independent of the other.
 

Of course, it does double the drilling, but that's the easy bit really.
 

This is also of course more or less how multi layer PCBs are made by fabricators, a stackup of already prepared pcb layers and resin impregnated sheets.
 

Single sided laminate at 0.8mm thick (and you can get down to 0.5mm) is available out of China for cheap.
 
 
 
 
 
Has anybody done this... am I reinventing a triangular wheel here, is it doomed to failure?  Suggestions on suitable adhesive... maybe just spray on contact adhesive might work, it's a pretty big flat contact area.
 
 
 
 
 

Re: [Homebrew_PCBs] Gluing 2 single sided boards to make a double sided board.

2015-07-06 by Harvey White

On Mon, 6 Jul 2015 02:35:13 +0000, you wrote:

>I would be more inclined to drill just two holes on opposite
>sides of a double-sided board before exposure/etching so
>that alinement would be a lot easier.

You'd like three, and asymmetrically placed (say three of the four
corners). It's possible to get the board reversed if you're not
careful, so the three holes guarantee that the boards are oriented
properly.

Harvey


>
>Best,
>Charlie
>
>On Sun, 5 Jul 2015 17:13:52 +1200 "James bitsyboffin@...
>[Homebrew_PCBs]" <Homebrew_PCBs@yahoogroups.com> writes:
>
>
>Double sided boards as we all know can be a bit of a pain, the biggest
>problem is getting that precise alignment between sides correct so that
>when you drill in the center of your pad on one side, it comes out in the
>center of the pad on the other (and not, as is not uncommon, breaking
>out, and probably messing up the trace, or a trace nearby...).
>Especially if your only able to expose/imprint artwork one side at a
>time.
>
>
>Even more frustrating when one side comes out perfect in part of the
>process (eg, developing) and the other side is too flawed to be useful,
>meaning you get to start from scratch again.
>
>
>So, the thought randomly occurred to me today, if you could prepare,
>expose, etch, drill the two sides of a double sided board completely
>separately, and join them up at the end of the process, it would make
>getting precise alignment of those sides almost a non-issue, assuming you
>can drill even roughly vertically and hit the center of the holes it's
>just a matter of lining up the holes you drilled on each side. And also
>means that the success or failure of each side is independent of the
>other.
>
>
>Of course, it does double the drilling, but that's the easy bit really.
>
>
>This is also of course more or less how multi layer PCBs are made by
>fabricators, a stackup of already prepared pcb layers and resin
>impregnated sheets.
>
>
>Single sided laminate at 0.8mm thick (and you can get down to 0.5mm) is
>available out of China for cheap.
>
>
>Eg:
>http://item.taobao.com/item.htm?spm=a1z10.5-c.w4002-1192550948.12.TIEXsq&
>id=35870048695
>
>http://item.taobao.com/item.htm?spm=a230r.1.14.4.VdTsRT&id=21105435798&ns
>=1&abbucket=3#detail
>
>
>
>Has anybody done this... am I reinventing a triangular wheel here, is it
>doomed to failure? Suggestions on suitable adhesive... maybe just spray
>on contact adhesive might work, it's a pretty big flat contact area.
>
>
>
>

Re: Gluing 2 single sided boards to make a double sided board.

2015-07-07 by Howard Chester

Here is a few tips to get good centering of vias & through holes.

1) Copy and paste your final PCB layout to the desktop & rename "xxx Shrink",(where xxx is your own board name)
2) Open your renamed copy & reduce all of the hole sizes to 0mm5 (0.5mm). Save and close.
3) Use the renamed copy as your master, Print & expose in whatever method you using(U.V. Toner Transfer etc)
4) Etch, clean & electroless plate(if used)
5) Use a spring loaded center-punch(google Automatic center-punch) on its lowest possible setting to "dimple" each hole & finally drill with a 0mm8(0.8mm) drill bit. Take your time with this step to achive precise holes!
6) Enlarge any other holes to their required diameters

Using this method takes longer but stops "run out" ,wandering & fewer bits snapping....AND gives you a near perfectly centered hole when using a Dremmel Drill & Stand
I hope this helps with tha alaignment problem on S/S double & D/S Boards
Chester

Re: [Homebrew_PCBs] Re: Gluing 2 single sided boards to make a double sided board.

2015-07-07 by Harvey White

On Tue, 7 Jul 2015 13:46:09 +0000 (UTC), you wrote:

>Here is a few tips to get good centering of vias & through holes.
>1) Copy and paste your final PCB layout to the desktop & rename "xxx Shrink",(where xxx is your own board name)2) Open your renamed copy & reduce all of the hole sizes to 0mm5 (0.5mm). Save and close.3) Use the renamed copy as your master, Print & expose in whatever method you using(U.V. Toner Transfer etc)
>4) Etch, clean & electroless plate(if used)5) Use a spring loaded center-punch(google Automatic center-punch) on its lowest possible setting to "dimple" each hole & finally drill with a 0mm8(0.8mm) drill bit. Take your time with this step to achive precise holes!
>6) Enlarge any other holes to their required diameters
>
>Using this method takes longer but stops "run out" ,wandering & fewer bits snapping....AND gives you a near perfectly centered hole when using a Dremmel Drill & StandI hope this helps with tha alaignment problem on S/S double & D/S BoardsChester


Dremel has a very bad chuck and bearings for PC board drilling. If
the stand has any kind of wobble in it, that will also have an effect.

If you have access to a Proxxon rotary tool, it has a 4 jaw chuck
rather than three, and is made of steel rather than aluminum.

I've found it to be better in performance, and I've tried both.

However, if the drill press mechanism wobbles from side to side, that
must also be fixed.

Harvey