Synth-DIY Yahoo! Groups Archives

Getting a PCB professionally manufactured

2014-05-07 by <beefyzee@...>

I've made a circuit board for myself which does something for my cnc plasma cutting table. There seems to be some sparks of interest for it but not at the cost at which I'd "knock one together" for them. I'd therefore have to look at getting them made in quantity at a professional circuit board manufacturer, but have no idea how they work.

Example, when I design a board for myself, I look at what components are available at the right price, then I design my board to suit.

I'm a bit confused though about how the PCB manufacturer chooses the components. They might not have that brand available, or the package is a slightly different size, etc. The board is the easy bit but I don't know how it works with component choice. How do you specify components when you don't know what the manufacturer has available to them, what brand, what quality, etc.

Am I making sense.

Keith.

Re: [Homebrew_PCBs] Getting a PCB professionally manufactured

2014-05-07 by Mitch Davis

Hello Keith,

On Wed, May 7, 2014 at 3:49 PM, <beefyzee@...> wrote:
>
> I've made a circuit board for myself
> which does something for my cnc
> plasma cutting table. I'd therefore
> have to look at getting them made
> in quantity at a professional circuit
> board manufacturer, but have no
> idea how they work.

Are you talking about just the PCB, or getting someone to provide the
boards and components and assemble them into a product for you?

If you're talking about the PCBs, then my company ("Hackvana") can
supply you 10 PCBs for as little as USD19 including shipping.

Here's my guide:

http://www.hackvana.com/guide

Here's a picture of some boards I supplied recently:

http://i.imgur.com/gplpNwO.jpg

And I supplied these PCBs and the stencil too:

http://lowpowerlab.com/blog/2014/03/23/getting-more-serious-about-smd-production/

And these:

http://ava.upuaut.net/?p=675

There are also several other suppliers you can use. Everyone has
their favourite.

> I'm a bit confused though about how the PCB manufacturer chooses the components. They might not have that brand available, or the package is a slightly different size, etc.

I'm assuming here that you're talking about PCBA (PCB assembly) not
PCBs. For PCBA that's a really important point. Sometimes it's done
by you purchasing the parts and sending them to the assembler.

> How do you specify components when you don't know what the manufacturer has available to them, what brand, what quality, etc.

I have lived for several years in Shenzhen China, electronics
manufacturing capital of the world, and that's a big issue. Part of
the problem is that parts (especially semis) that we in the West think
of as common and garden-variety are sometimes not that common in
China, and vice versa. The two sides of the Pacific have different
ideas of what a standard part is. Generally what people do is hire
someone to do their part sourcing in China. Also, you always want to
make a small number of prototypes using exactly the same boards and
parts as you intend to use when you go for production.

> Am I making sense.

Yeah sure, except for the confusion w/ PCB vs PCBA.

My regards, hope this helps!

Mitch.

(This group's rules say: "If you are posting for your own business,
please limit ads to once a month")

Re: [Homebrew_PCBs] Getting a PCB professionally manufactured

2014-05-07 by David Lyon

Hello,

If you have a look here - https://plus.google.com/u/0/+DavidLyon/posts

There's a few more examples of hackvana pcb's.

On Wed, May 7, 2014 at 4:02 PM, Mitch Davis <mjd@...> wrote:

Hello Keith,

On Wed, May 7, 2014 at 3:49 PM, <beefyzee@...> wrote:
>
> I've made a circuit board for myself
> which does something for my cnc
> plasma cutting table. I'd therefore

> have to look at getting them made
> in quantity at a professional circuit
> board manufacturer, but have no
> idea how they work.

Are you talking about just the PCB, or getting someone to provide the
boards and components and assemble them into a product for you?

If you're talking about the PCBs, then my company ("Hackvana") can
supply you 10 PCBs for as little as USD19 including shipping.

Here's my guide:

http://www.hackvana.com/guide

Here's a picture of some boards I supplied recently:

http://i.imgur.com/gplpNwO.jpg

And I supplied these PCBs and the stencil too:

http://lowpowerlab.com/blog/2014/03/23/getting-more-serious-about-smd-production/

And these:

http://ava.upuaut.net/?p=675

There are also several other suppliers you can use. Everyone has
their favourite.

> I'm a bit confused though about how the PCB manufacturer chooses the components. They might not have that brand available, or the package is a slightly different size, etc.

I'm assuming here that you're talking about PCBA (PCB assembly) not
PCBs. For PCBA that's a really important point. Sometimes it's done
by you purchasing the parts and sending them to the assembler.

> How do you specify components when you don't know what the manufacturer has available to them, what brand, what quality, etc.

I have lived for several years in Shenzhen China, electronics
manufacturing capital of the world, and that's a big issue. Part of
the problem is that parts (especially semis) that we in the West think
of as common and garden-variety are sometimes not that common in
China, and vice versa. The two sides of the Pacific have different
ideas of what a standard part is. Generally what people do is hire
someone to do their part sourcing in China. Also, you always want to
make a small number of prototypes using exactly the same boards and
parts as you intend to use when you go for production.

> Am I making sense.

Yeah sure, except for the confusion w/ PCB vs PCBA.

My regards, hope this helps!

Mitch.

(This group's rules say: "If you are posting for your own business,
please limit ads to once a month")

RE: [Homebrew_PCBs] Getting a PCB professionally manufactured

2014-05-07 by Boman33

Keith,

Depending on your arrangement with the contract manufacture you can just send your current BOM and PCB layout. Typically the contract manufacturer will look for equivalent available components and can tweak the layout if there are required changes (of course with your approval).

Bertho

From: beefyzee@... Sent: Wednesday, May 07, 2014 01:50

I've made a circuit board for myself which does something for my cnc plasma cutting table. There seems to be some sparks of interest for it but not at the cost at which I'd "knock one together" for them. I'd therefore have to look at getting them made in quantity at a professional circuit board manufacturer, but have no idea how they work.

Example, when I design a board for myself, I look at what components are available at the right price, then I design my board to suit.

I'm a bit confused though about how the PCB manufacturer chooses the components. They might not have that brand available, or the package is a slightly different size, etc. The board is the easy bit but I don't know how it works with component choice. How do you specify components when you don't know what the manufacturer has available to them, what brand, what quality, etc.

Am I making sense.

Keith.

RE: [Homebrew_PCBs] Getting a PCB professionally manufactured

2014-05-07 by Tony Smith

I've made a circuit board for myself which does something for my cnc plasma cutting table. There seems to be some sparks of interest for it but not at the cost at which I'd "knock one together" for them. I'd therefore have to look at getting them made in quantity at a professional circuit board manufacturer, but have no idea how they work.

Example, when I design a board for myself, I look at what components are available at the right price, then I design my board to suit.

I'm a bit confused though about how the PCB manufacturer chooses the components. They might not have that brand available, or the package is a slightly different size, etc. The board is the easy bit but I don't know how it works with component choice. How do you specify components when you don't know what the manufacturer has available to them, what brand, what quality, etc.

Am I making sense.

Keith.

In order of costs (and hassle) it’s bare PCB, kits, then assembled boards.

If it’s just the PCB then the manufacturer doesn’t care what the parts are. They make it and send it back. You then send the PCB to people with a list of parts they need to buy.

Usually saying “R1 1k .25W” for generics is enough, or you can supply seller part numbers, eg digiKey or Mouser.

Something like an inductor where the footprint might change or an LED with particular brightness is different; there you need to tell people exactly what part. Again for just getting the PCB made it doesn’t matter.

The next step up is you supplying a kit, in that case you’d buy the parts. That’s possibly the best option, though it’s a bit of an up-front cost to you. Buyers are happy they don’t have to chase down all the bits, especially if there’s an odd-ball part in there.

If you want the PCB maker to also add the parts (stuffing) then you need to supply the part numbers (BOM), they’ll tell you if there’s a problem. They’ll rarely change the layout, more common is substituting a cheaper part, eg lower voltage rating for capacitors.

That also drives up the cost which can be a large up-front cost.

Tony

Re: Getting a PCB professionally manufactured

2014-05-07 by <alienrelics@...>

Just so there is no confusion, here is the relevant excerpt from the list rules:

"Suggestions, recommendations and such, to and from professionals and companies are welcome. If you are posting for your own business, please limit ads to once a month and feel free to post your site in the Links area. Company representatives are encouraged to respond to legit requests for information as long as you identify your connection. IE, don't pretend to be an unconnected customer, there are enough savvy people here that you'll be found out quickly. Just use common sense about replying or people might think you are flogging your business."

The limit on posting is for -ads-, not for responses to requests for information. I'm happy to see company reps posting here.

Steve Greenfield AE7HD

listowner Homebrew_PCBs

Re: [Homebrew_PCBs] Re: Getting a PCB professionally manufactured

2014-05-07 by David Lyon

Hi Steve,

It's May 7 by my clock.

Is that rule per calendar month? or every 30.5 days? As it might give different results.

Regards

David

On Wed, May 7, 2014 at 7:56 PM, <alienrelics@...> wrote:

Just so there is no confusion, here is the relevant excerpt from the list rules:

"Suggestions, recommendations and such, to and from professionals and companies are welcome. If you are posting for your own business, please limit ads to once a month and feel free to post your site in the Links area. Company representatives are encouraged to respond to legit requests for information as long as you identify your connection. IE, don't pretend to be an unconnected customer, there are enough savvy people here that you'll be found out quickly. Just use common sense about replying or people might think you are flogging your business."

The limit on posting is for -ads-, not for responses to requests for information. I'm happy to see company reps posting here.

Steve Greenfield AE7HD
listowner Homebrew_PCBs

Re: [Homebrew_PCBs] Re: Getting a PCB professionally manufactured

2014-05-07 by Mitch Davis

Hello Folks,

On Wed, May 7, 2014 at 4:06 PM, David Lyon <david.lyon.preisshare@...> wrote:
>
> If you have a look here - https://plus.google.com/u/0/+DavidLyon/posts
>
> There's a few more examples of hackvana pcb's.

I recognise most of those boards! David's been a prolific experimenter over the past year. I think there's hardly a month when he's not getting some boards for a new project.

On Wed, May 7, 2014 at 7:56 PM, <alienrelics@...> wrote:

Just so there is no confusion, here is the relevant excerpt from the list rules:

Company representatives are encouraged to respond to legit requests for information as long as you identify your connection.

I should also mentioned I'm a hobbyist, and I have made boards at home. Still do from time to time. If anyone is reading this and would like to make boards at home, but is having trouble putting all the pieces together, here's one way. I've tried to make it one-stop:

http://capnstech.blogspot.com/2011/05/playpause-making-pcbs-at-home.html

Mitch.

Re: [Homebrew_PCBs] Getting a PCB professionally manufactured

2014-05-07 by Harvey White

On 06 May 2014 22:49:56 -0700, you wrote:

>I've made a circuit board for myself which does something for my cnc plasma cutting table. There seems to be some sparks of interest for it but not at the cost at which I'd "knock one together" for them. I'd therefore have to look at getting them made in quantity at a professional circuit board manufacturer, but have no idea how they work.

As has been mentioned, either you do bare boards as a kit, or supply
the parts to the board stuffer, or have them get the parts.

>
>
> Example, when I design a board for myself, I look at what components are available at the right price, then I design my board to suit.
>

That's what a company making a PC board will do, either in house or
any combination. Custom parts (programmed ROMS, processors, FPGA,
etc, they generally supply themselves or put them in sockets (if..).

>
> I'm a bit confused though about how the PCB manufacturer chooses the components. They might not have that brand available, or the package is a slightly different size, etc. The board is the easy bit but I don't know how it works with component choice. How do you specify components when you don't know what the manufacturer has available to them, what brand, what quality, etc.

Critical stuff you send to them.

However, this is the most expensive way of doing a board, so the cost
goes up.

As an example of prices I've seen, (and this is only one example), 20
dollars to make the board, then another 20 to 30 to stuff it. At that
cost, I think you had to supply your own parts. Alternatively, you
could (assuming surface mount), add the larger and more expensive
chips with a hundred pins or so, and they put them on, with you doing
the easier parts like resistors, etc.

Most of them seem to be flexible.

No experience here, since I do it all myself.

Harvey

>
>
> Am I making sense.
>
>
>
> Keith.
>

RE: [Homebrew_PCBs] Getting a PCB professionally manufactured

2014-05-07 by Boman33

One quick additional comment:

If the products are for SMT boards and using Pick & Place machines for automatic assembly it is better to let the manufacturer supply the parts. Providing the wrong carrier format for the parts, the manufacturer might not be able to properly load them in the pick & place machine.

It is a headache when we get orders for low prototype runs to deal with these problems.

Bertho

www.Vinland.com

From: Tony Smith Sent: Wednesday, May 07, 2014 03:51
I've made a circuit board for myself which does something for my cnc plasma cutting table. There seems to be some sparks of interest for it but not at the cost at which I'd "knock one together" for them. I'd therefore have to look at getting them made in quantity at a professional circuit board manufacturer, but have no idea how they work.

Example, when I design a board for myself, I look at what components are available at the right price, then I design my board to suit.

I'm a bit confused though about how the PCB manufacturer chooses the components. They might not have that brand available, or the package is a slightly different size, etc. The board is the easy bit but I don't know how it works with component choice. How do you specify components when you don't know what the manufacturer has available to them, what brand, what quality, etc.

Am I making sense.

Keith.

Re: Getting a PCB professionally manufactured

2014-05-07 by <cs6061@...>

Kieth,
There are a lot of variants to the process. All the way from writing a speck of what the board does and its requred form factor and letting the contract house do everything necessary to deliver you tested and working boards all the way down to just getting a bare board fabricated from your Gerber file.   I have always worked for a company that had an inhouse PCB department. In the early days before CAD you could even hand them tablet paper sketches of your schematic and they would draw it up on D size vellum for your approval. Usually the company had an in-hous parts list to choose parts from. If you had a new part the components group would have to research it and add it to the approved parts list.   Most engineers would do their own schematic drawings because redrawing from sketches was error prone. You would submit a schematic, BOM and some mechanical and get back a board weeks later.   With the introduction of CAD things got much easier with less errors and shorter correction cycles.

Choosing the parts for your design was always an issue and as important as your schematic. A board that can't be assembled because the parts are unavailable, don't fit, are too expensive, or of incorrect parameters is worthless. I always find this is the most time consuming part of board design. In the early through hold days before there were global foot print specks all the parts were different, you designed in Mfg A's part but Mfg B's wouldn't fit.

Now with SMT a good percent of the foot print issues have been mitigated with good global specifications.   But it still takes a lot of time to pick the correct part. Lots of things to consider, is it correct electrically, is the size what you need, is it available, what is the production lead time for quantity, how is it packaged --tape and real, trays, loose -- the assembly folks need this info.

There is no easy answer, it all depends on your process flow.

For my home boards that I get professionally fabricated. I draw the schematic using my own standard library of parts I have built up over time. This way I can buy a real of 1000 caps at the same price as buying 50 pieces and keep using them on multiple designs.   For new parts I spend hours and hours on Digikey and others finding just what I want with the specks I need, with the package I want at a cost I can accept and that is available. Nothing worse than finishing up a board layout and finding out DigiKey is out of stock and the lead time is 20 weeks. Then I make sure I have all the correct footprints for the parts I am using. Only then do I layout the board.   The footprint and schematic symbol management is another reason to build your own set of standard parts to use. That way you get to check these items once and don't have to be constantly reinventing the wheel making new parts.   Once the board is finished I submit the Gerbers to the PCB fabricator or make it my self (doing much less of this).

I have not had any home boards comercially assembled yet. Most of the PCB fabricators have assembly capability or have partners that can provide this service. If thinking this route the first thing would be to contact them and get their requirements.   I would guess most will let you supply the parts or will buy them for you based on your BOM documentation. Keep in mind its going to cost you a lot more if you give them ziplock bag of parts vs providing the parts on reels for the pick and place machine. The volume of boards to be built is also a huge item to consider -- normally doesn't make sense to program the pick and place for one board unless you have parts that must be machine placed.

So my flow goes like this:
High level your design -- pick your parts --check parts availability -- build your schematic symbols and footprints -- draw up the schematic -- layout the pcb -- check the net list for sanity (catches symbol or footprint screw ups) -- review the gerber -- RFQ the board and get it on order -- place and solder the parts -- test the board.

Craig

Re: Getting a PCB professionally manufactured

2014-05-07 by Paul Alciatore

You need to contact some of the PCB assembly companies to get the
exact details and, of course, prices.

I have purchased bare boards in small quantities (up to 50 in one
order). There are many companies that will do this. And many of them
will assemble the boards for you.

One of my favorites is Advanced Circuits. They will do one or three
boards for prototype work or any number for production.

http://www.4pcb.com/

They also do assembly, either with parts that you supply or they will
supply them or a combination of both.

http://www.onestopassembly.com/

I have not used their assembly services so do contact them AND OTHERS
for the details.

One thing that I would think would be absolutely required is that you
should be absolutely sure of the design and the fit of the parts
before placing an order. Do one or more prototype boards first and be
sure to use the actual parts that will be used in the final assembly.
Fiberglass does not stretch worth a darn.

If you are using some of the smaller pitch devices, like BGAs, you
may want to have them assemble the prototypes too. It will cost a bit
per board, but you can be assured of a proper assembly. Add the cost
of those prototypes to the first run of production boards when
figuring the sale price.

Re: Getting a PCB professionally manufactured

2014-05-07 by <beefyzee@...>

Good Morning guys (I'm in Australia), and first of all:

THANK YOU VERY MUCH EVERYONE. I didn't expect such a great response. I've now got a much better insight into what's involved.

Regarding assembly I think I'm leaning more towards a low quantity test run of boards and FOR NOW I'll put the components on myself. If more serious interest in my little board is shown as word gets around, then I can look into getting the assembly done for me too. I feel like I'll be more of a hassle to a manufacturer at present if I go the assembly route.

I'll have to do some research on soldering SMD components. Some say that once you get the hang of it you'll find it easier and quicker than through hole components. If that turns out to be true I'll redesign the board with SMD parts, which will also reduce the size. And having a professionally made board with solder mask should help greatly.

Making the PCB itself is actually quite easy for me but the hole drilling is the hard bit. I ended up mounting an electric die grinder on my 2400 x 1500 CNC plasma table and drilled the holes that way, talk about shooting a fly with a bazooka. Too much hassle overall when I look at the pictures of the professionally made boards, they look beautiful.

It's quite a simple board and as a hobbyist I've made everything big and chunky, much bigger than necessary. For a PCB manufacturer I think they won't come much simpler / easier, no fine tolerances here.

Keith.

Re: [Homebrew_PCBs] Re: Getting a PCB professionally manufactured

2014-05-08 by James

In that case, there's a multitude of pcb fab houses that can churn out your PCB in small quantities, ranging from very high quality, to only-really-prototype-grade.

Check out: http://pcbshopper.com/

Doesn't look like they have Hackvana on there yet, Mitch should contact them.

On 08/05/14 11:49, beefyzee@... wrote:

Regarding assembly I think I'm leaning more towards a low quantity test run of boards and FOR NOW I'll put the components on myself.

Re: [Homebrew_PCBs] Re: Getting a PCB professionally manufactured

2014-05-08 by Harvey White

On 07 May 2014 16:49:49 -0700, you wrote:

>Good Morning guys (I'm in Australia), and first of all:
>
> THANK YOU VERY MUCH EVERYONE. I didn't expect such a great response. I've now got a much better insight into what's involved.

Yer welcome.....

>
>
> Regarding assembly I think I'm leaning more towards a low quantity test run of boards and FOR NOW I'll put the components on myself. If more serious interest in my little board is shown as word gets around, then I can look into getting the assembly done for me too. I feel like I'll be more of a hassle to a manufacturer at present if I go the assembly route.
>

Good idea in terms of money, I think. BGA stuff you want them to do,
leaded flatpacks, you can do.

>
> I'll have to do some research on soldering SMD components. Some say that once you get the hang of it you'll find it easier and quicker than through hole components. If that turns out to be true I'll redesign the board with SMD parts, which will also reduce the size. And having a professionally made board with solder mask should help greatly.
>

Just as easy, in the long run.

Solder mask helps greatly. You need a very good temperature
controlled iron. I use Metcal myself.

Use lots of flux when soldering flatpacks. If you solder blob
anything, do not panic. Just keep on going with the rest of the pins.
Practice will help. I use solder wick with an added flux (it helps
me). That sucks off the excess solder, and the solder that flows
under the chip (don't ask), comes out on the wick. You will get the
hang of it. A super small tip is not as needed, but one that covers
one or two pins is good enough, this on 0.5mm spacing pins, TQFP-100
or TQFP-144.

For resistors/capacitors, I generally put a small blob of solder on
the pad, (use flux, RMA is good), and then heat the pad and push the
part onto the pad using a pair of tweezers. Then at a later date,
solder the other end of the part. Again, if it makes sense, it'll
work well.

>
> Making the PCB itself is actually quite easy for me but the hole drilling is the hard bit. I ended up mounting an electric die grinder on my 2400 x 1500 CNC plasma table and drilled the holes that way, talk about shooting a fly with a bazooka. Too much hassle overall when I look at the pictures of the professionally made boards, they look beautiful.
>

Hole drilling is easy enough with a smaller (carbide) drill. I will
use #76 or so for feedthroughs.

Now plating through the holes, that's another matter. I hand drill
the holes (using a Proxxon with 1/8 collet, carbide drills, and at the
highest speed for small holes). You need a sensitive drill press as
well, no wobble at all. Then thread wire through, and solder one
side, then the other, then cut all the wires.

I'd prefer plated through holes, thank you very much.

>
> It's quite a simple board and as a hobbyist I've made everything big and chunky, much bigger than necessary. For a PCB manufacturer I think they won't come much simpler / easier, no fine tolerances here.
>

Pads are a little larger because of hand soldering, that works well.

>

Harvey

> Keith.

Re: [Homebrew_PCBs] Re: Getting a PCB professionally manufactured

2014-05-08 by Mitch Davis

On Thu, May 8, 2014 at 10:14 AM, James <bitsyboffin@...> wrote:

In that case, there's a multitude of pcb fab houses that can churn out your PCB in small quantities, ranging from very high quality, to only-really-prototype-grade.

Check out: http://pcbshopper.com/

Doesn't look like they have Hackvana on there yet, Mitch should contact them.

Mr. PCB Shopper kindly contacted me but I declined. The site seems to optimise for price. My strength is to offer first-rate service above all, while being affordable. All my growth has come from happy customers telling their friends. So I know everyone and many have become good friends.

http://dangerousprototypes.com/2012/12/06/workshop-video-interview-with-mitch-from-hackvana/

My regards.

Re: Getting a PCB professionally manufactured

2014-05-08 by <cs6061@...>

Kieth,
Soldering smt parts is not all that hard, it helps to have a zoom binocular microscope, a steady hand, a good soldering iron and fine solder with a (RMA) flux. I use a Metcal soldering iron and its hands down the best of the breed. A head band jewelers loop works fairly well but and old B&L stereo scope is better, you only need a few power. Too much power and the lense is too close to the work to be of any use.

I try and keep my SMT components on the larger side say 0805 or above for resistors and caps. I have done 0603's but they a lot harder to do then 0805's.

I think SMT is actually easier to do the through hole, no leads to bend or clip.

Craig

Re: [Homebrew_PCBs] Re: Getting a PCB professionally manufactured

2014-05-08 by Mitch Davis

On Thu, May 8, 2014 at 2:13 PM, <cs6061@...> wrote:

Soldering smt parts is not all that hard, it helps to have a zoom binocular microscope, a steady hand, a good soldering iron and fine solder with a (RMA) flux.

Flux is the key to soldering chips. And you can find lots of good SMT soldering videos on youtube.

I try and keep my SMT components on the larger side say 0805 or above for resistors and caps. I have done 0603's but they a lot harder to do then 0805's.

1206s or 0805s are a good size to start with. Here's my 11yo son soldering 1206s. He'd never soldered before:

http://capnstech.blogspot.com.au/2011/06/playpause-3-assembly-and-programming.html

I think SMT is actually easier to do the through hole, no leads to bend or clip.

Me too. If you can get over the mystery, SMT is great.

Mitch.

Using 3-D printers to for PC-board fabrication?

2014-05-09 by Brad Thompson

Hello--

Below you'll find a couple of postings (originally made to the Glowbugs
and QRP-L
newsgroups) regarding the possible use of 3-D printing methods as a means of
depositing etch resist onto bare copperclad board to create circuit
boards. Please refer
to my original posting at this message's end.

Also, I'm a newcomer to this newsgroup so please accept my apologies if
this
topic has already been covered in depth.

73--

Brad AA1IP
******************************************************************************

I'm posting John's thoughtful comments (which I very much appreciate) below
and inserting my responses. My original posting is appended.

On 5/6/2014 11:39 AM, John D'Ausilio wrote:
> Responses inline (since there are so many questions
>
>
> Questions and caveats:
>
> --Component pads' shapes may not translate well from Gerber code--
> i.e., several overlapping passes would be needed to make large pads.
> In general, printers which extrude ABS or PLA use a tip with a 0.4mm
> hole. The resulting "noodle" is generally around 0.5mm wide and
> roughly circular in cross-section.

Hello, John and the groups--

Depending on the "squishdown" factor, a 0.5 mm wide noodle might produce
a 0.020 inch wide trace. If the noodle doesn't become a semicircle upon
contact with the copperclad surface, the trace width would be narrower.
> --Extruded plastic may not adhere well to copper.
>
> --Unetched copperclad board may need to be heated for best trace
> adhesion.
> Getting the plastic to adhere to the build platform is challenging.
> ABS is usually printed on a heated metal plate covered with Kapton, or
> lately on a heated glass plate sprayed with cheap hairspray.
> I can try clipping some copperclad to my build plate and see what
> happens ..
Copper's higher thermal conductivity might be our friend. Imagine
using a couple of Dale RH-50 chassis-mounted wirewound resistors
clipped to opposite sides on top of the copperclad board. The resistors
could provide auxiliary heating.

> --Dimensional issues: how accurately can a 3-D printer locate coordinates
> at distant extents of a large layout?
> Machines with orthogonal mechanics have the same accuracy at all
> points on the build plate. Machines with delta mechanics lose
> resolution towards the edges. The vast majority of hobbyist printers
> are orthogonal.
Excellent!
>> --What's the narrowest (or widest) trace that can be extruded?
>>
>> For general object printing the goal is to squash the first layer into
>> the build plate, reducing it's diameter and spreading it out.
>> Realistically you could probably achieve around 0.55 or so with a .4mm
>> nozzle
Converting 0.55 mm to inches would produce traces a whisker under 0.22
inches in width.
> --How accurate can the copperclad board be leveled on the printing stage?
>
> We already level our platforms, assuming the copperclad is
> dimensionally stable over 20C-100C range (we usually heat to 100C for
> ABS) then leveling shouldn't present a problem.
One online source lists "...G-10 and FR-4 are rated at 285 degree F
continuous operating
temperature..." but I didn't locate a value for horizontal coefficient
of expansion.
>> --How well do various types of extruded plastic resist commonly-used
>> copper
>> etching solutions?
>>
> That's the $1000 question .. almost all printers in hobbyist use will
> print ABS or Polylactic Acid (PLA). I don't etch boards so I have no
> chemicals here, but I'd be happy to send you some samples.
The "go to" source for chemical resistance is apparently Cole-Parmer:

http://www.coleparmer.com/Chemical-Resistance?referred_id=11033&mkwid=sJFDnHw4J&pcrid=12430988319&kw=%2Bchemical%20%2Bresistance%20chart&mt=b&pdv=c&gclid=CLC49vnUl74CFe99OgodbF4A_w

...Or TinyURL...

*http://tinyurl.com/jwnnbk2

Commonly-used etchants include ferric chloride, hydrochloric acid,
ammonium persulfate
and vinegar.

ABS resistance:

Vinegar A-- Excellent
*
Ferric Chloride A-- Excellent

Hydrochloric Acid 20% A-Excellent

Ammonium Persulfate A^2 -Excellent (2 = satisfactory to +120 F (+48 C)

I couldn't locate a reference for polylactic acid's chemical resistance,
but I'm pressed for time.

-Could you use different colored extrusion plastics to mark, say, power
and ground traces?
> Not easily .. it's very challenging to print more than one color at
> the same height (you would need more than one nozzle, and a way to
> move them away from the piece so the unused one didn't plow into
> existing plastic)
Okay-- variously-colored resist would be a bonus.
> --Could you leave the extruded plastic traces in place as a solder mask
> and clean the plastic away only from component pads requiring soldering?
> All of our plastics melt at 220C or less .. not compatible with
> soldering temps.
That might not be a problem if the plastic melts short of contaminating
the solder
joint. Careful removal (mechanical abrasion?) of the resist on the pads
would
be necessary.

Further comments from all are welcome!

73--
Brad AA1IP
********************************

Original posting follows:

Excuse the somewhat off-topic nature of this posting, but
I'm picturing the Glowbug application (i.e., custom component-terminal
boards) along with QRP and general circuit-design applications.

Has anyone in the group used a 3-D printer to create one-off PC boards?
Consider this as the inverse process of removing copper via a
CNC milling machine.

***********
Here's how the process might work; unfortunately, I don't own a
3-D printer, and thus the following description is theoretical and
riddled with caveats.

1.) Create a PC-board layout using any of several available tools.

2.) Translate the layout program's output into an X versus Y format
understood by the 3-D printer.

3.) Extrude plastic to "draw" the layout's traces on a sheet of copperclad
board.

4.) Etch the board.

5.) Remove the plastic traces and drill holes in pads to accommodate
through-hole components' leads; tin-plate the board if desired.
******

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Re: Getting a PCB professionally manufactured

2014-05-11 by beefyzee@...

Thanks again everyone.

Having read what you guys have told me, been watching a few Youtube videos on SMD soldering since I was last here (been sick since then), and despite having not done it yet, I think I will end up preferring SMD once I get kitted up with all the necessary tools and materials. It looks like it will be a lot faster than through hole. I use my "Inspector Gadget" headband magnifier when I'm soldering TH so I'll probably flip down the 2nd lens when I'm doing SMD, but I can see one of those magnifying lamps being a much easier way of doing it. You're always flipping the headband ones up and down and it gets a bit irritating.

If this little venture goes anywhere I can see myself rigging up a little component hold down frame, where the PCB is fixed in position and there's an arm you can quickly move to any position on the board to press down on a component and hold it in position while it gets soldered. Maybe something like that is already out there.

I've just compared my through hole 2N7000 FETs with their 2N7002 SMD brothers, and wow, how can SMD be so much tinier, OR why on earth are through hole so big to start off with. The interesting thing I noticed however, from looking at the data sheet, is that the SMD "equivalent" can have less desirable specs. I'm prototyping my board with TH components but I'll probably have to get an SMD board professionally made and "hope" everything works just as good. Has a "Eureka" moment with thoughts on the circuit so I'm back at the schematic stage making improvements to make it easier for the end user, and also make it available to a wider customer base.

I'm starting to see why those little PCBs are not always so cheap LOL.

Keith.

RE: [Homebrew_PCBs] Getting a PCB professionally manufactured

2014-05-12 by Mark Harrison

Hi Keith,

It really depends on the number of boards you want.

If it’s only a couple, a small assembler just needs to know where you got the components, and they’ll hand assemble everything.

On the other hand if you want to do, say, 50-1,000, it may be worth using a bigger company with automated systems.

In my experience the larger PCB assembly companies keep stocks of their favourite “preferred” components and can supply you with a list.

This is useful for getting quick prototypes and small runs made as you don’t need to buy large reels of components to suit their machines, and they don’t need to spend time putting loose components onto reels to suit their machines. Their components may also be a lot cheaper as they buy in much larger quantities.

In some cases I’ve purchased and supplied the components myself. It can be faster than waiting for the assembler to go through their internal process of purchasing, etc, especially if I already have them on hand or they are specialised parts from companies they don’t normally deal with.

Beware though, as some PCB assemblers insist on having components delivered in the manufacturers original packaging (so components are dry and leads are not tarnished or bent, etc). And rightly so – it’s the only way to maintain high quality control.

Sometimes the assembler provides a sourcing service where you can specify exactly what components you want, and they will buy them in, or they will recommend alternatives. However you will probably end up paying for more components than you need. This is because the assembler may prefer to buy whole reels of components whereas you would buy exactly the number you need. They will also buy extra components with the expectation that some will get lost or damaged during the manufacturing process. Sometimes the assembler will have to buy in a special component for you in much greater quantities than you need (maybe it’s only available in a large MOQ). If they are really nice, they may store the excess components and offer to sell them to other clients, so you only pay for leftovers if they don’t get used after a few years.

Some assemblers just take you design and replicate it, for better or worse.

The best thing is to supply them with as much information as possible, along with a sample board so they can look at it in detail (but be wary of overseas companies that copy your design and sell it on the open market without you knowing – maybe you don’t want to give them firmware or programming details unless you trust them!).

A good assembly house will help you refine your design for production. If your PCB has surface mount components then they will probably get you to change the component pad sizes to best suit their soldering processes. Ask for their design rules early in your PCB layout designing. It may cost more in the short term but end up cheaper in the long run and maybe have a better more reliable product.

Good luck,

Mark

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] On Behalf Of beefyzee@...
Sent: Wednesday, 7 May 2014 03:50 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Getting a PCB professionally manufactured

I've made a circuit board for myself which does something for my cnc plasma cutting table. There seems to be some sparks of interest for it but not at the cost at which I'd "knock one together" for them. I'd therefore have to look at getting them made in quantity at a professional circuit board manufacturer, but have no idea how they work.

Example, when I design a board for myself, I look at what components are available at the right price, then I design my board to suit.

I'm a bit confused though about how the PCB manufacturer chooses the components. They might not have that brand available, or the package is a slightly different size, etc. The board is the easy bit but I don't know how it works with component choice. How do you specify components when you don't know what the manufacturer has available to them, what brand, what quality, etc.

Am I making sense.

Keith.

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Re: Getting a PCB professionally manufactured

2014-05-12 by beefyzee@...

Thanks Mark,

that's good "nitty gritty" information, and helps me to clarify in my head how I would approach a manufacturer when/if I'm ready to get assembly done too. I think I should be safe enough from the pirates, this board will probably only sell in the hundreds after some considerable time. It's a fairly niche market and one where if you can't give technical support, word will get around quick. It's also got a micro-controller on board and even if fully assembled I'd program the chip on the board.

To be honest for my first run I'd probably be happy with as little as 10 boards and see if I can move them, and how quickly I can move them. Of course it the manufacturer works on a minimum blank size then I'll get as many boards made as can fit on there. That will also give me a taste of how well and how quickly I can do the SMD soldering, and see it the cost savings are worth it.

The information you guys have gave me has made me realise how little information one manufacturer gave me. Maybe he didn't want my business LOL.

Mitch from Hackvana has a customer guide explaining a few things, that's a good way to operate.

Keith.