Homebrew_PCBs

Here is a thought. I think?

What if you take and cover a board in vinyl sign material, cut the board
design out on the board and remove what you do not want. Then sand blast
the board with a fine medium to remove the excess copper.

Flame suit on,
now fire away

Brian G.

You mean like this?

http://groups.yahoo.com/group/Homebrew_PCBs/message/572

http://groups.yahoo.com/group/Homebrew_PCBs/files/Sign%20Cutter%20to%20make%20PCBs/

You don't want to stick it onto the board before you cut it. For a
variety of reasons: 1. you'll dull the point of the cutting blade
as it slightly scores the copper 2. you will not be able to "weed"
the vinyl (ie, lift off the areas you want to etch) because that
stuff sticks like gangbusters 3. few vinyl cutters will feed a
rigid thick board.

To sandblast that much metal away, you'll need to use a special
sandblast resist vinyl, not regular sign vinyl. I'd be worried that
the thick stuff won't allow very thin traces or holes, and that it
may blow off on the thin traces.

Flame suit? Who's going to flame you for brainstorming? That is
what this list is for!

Steve Greenfield

--- Brian Gracia <bgracia@...> wrote:

> Here is a thought. I think?
>
> What if you take and cover a board in vinyl sign material, cut
> the board
> design out on the board and remove what you do not want. Then
> sand blast
> the board with a fine medium to remove the excess copper.
>
> Flame suit on,
> now fire away
>
> Brian G.

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Hi

This is a bit of a strange question. I keep stumbling into strange (but
interesting)
projects to play with.

What is the maximum vibration level and/or G force standard smt or thruhole
will tolerate ?

I've been asked if I could figure out a electronic detonator for an
airburst charge
for snow guns. These are the guns/mortars they use to fire 4-8lb charges at
potential slides to trigger them. The trigger will be a pic that simply counts
and then fires a electric match after the preset delay.

I'm hoping this will prove tremendously difficult so I get to "work" and
have to blow
things up all winter ;-]

Tia

Dave

Brian:
I forsee that way being extremely difficult! Even if it worked I would think you could only do simple geometric shapes because of the nature of vinyl. Very creative however!

-Randy Knutson


What if you take and cover a board in vinyl sign material, cut the board
design out on the board and remove what you do not want. Then sand blast
the board with a fine medium to remove the excess copper.

Flame suit on,
now fire away

Brian G.


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[Non-text portions of this message have been removed]

I don't think this is OT.

I think it really depends a -lot- on the solder used, how it was
soldered, etc. NASA and anything for the military gets tested to
death in vibration and G-force testing. Anything automotive gets
similar testing at a much lower level. Poor solder joints that will
last years in a small circuit on your test bench may last a day in
a car or a pinball game.

How many G's a board can take is going to depend a lot on how it is
supported. Same with vibration. Anything that sticks up high from
the board is going to be more susceptable to damage.

I think an important part of this is going to be isolating the
shock of the charge from the boards. I've seen wiring get
overlooked- short straight segments of solid wire are going to
transfer shock a lot more than very slack sections of very flexible
stranded wire. Test lead wire is meant to take a lot of bending
without breaking.

Steve Greenfield

--- Dave King <KingDWS@...> wrote:

> Hi
>
> This is a bit of a strange question. I keep stumbling into
> strange (but
> interesting)
> projects to play with.
>
> What is the maximum vibration level and/or G force standard smt
> or thruhole
> will tolerate ?
>
> I've been asked if I could figure out a electronic detonator for
> an
> airburst charge
> for snow guns. These are the guns/mortars they use to fire 4-8lb
> charges at
> potential slides to trigger them. The trigger will be a pic that
> simply counts
> and then fires a electric match after the preset delay.
>
> I'm hoping this will prove tremendously difficult so I get to
> "work" and
> have to blow
> things up all winter ;-]
>
> Tia
>
> Dave

__________________________________________________
Do You Yahoo!?
Yahoo! - Official partner of 2002 FIFA World Cup
http://fifaworldcup.yahoo.com

If you do it the same way you make a sign, ie, cut the vinyl and
weed it on the backing as intended and then transfer to the copper
and acid etch rather than sandblast, it doesn't take long and is
not too hard.

You cannot do small shapes or holes, though. I had to modify the
layout of my boards so it was just simple rectangular shapes and
not small pads connected by narrow traces.

I could have done smaller shapes, though, if I'd not been using
really old vinyl and an old dull blade. ;')

You'd be surprised how small some vinyl cutters can cut. However,
the thick sandblast resist vinyl/rubber must use a shallower angle
blade and therefore is limited in how small a shape it can cut.

Steve Greenfield

--- Randy Knutson <ken_ryder@...> wrote:

>
> Brian:
> I forsee that way being extremely difficult! Even if it worked I
> would think you could only do simple geometric shapes because of
> the nature of vinyl. Very creative however!
>
> -Randy Knutson
>
>
> What if you take and cover a board in vinyl sign material, cut
> the board
> design out on the board and remove what you do not want. Then
> sand blast
> the board with a fine medium to remove the excess copper.

__________________________________________________
Do You Yahoo!?
Yahoo! - Official partner of 2002 FIFA World Cup
http://fifaworldcup.yahoo.com

Steve is exactly right here.
A lot of my boards go on small engines the vibration is very bad.
I learned the hard way on the first few. You will find that the
IC chips will not be hurt because they are low to board but the
solder joints will be weakened or crack if not perfect. The biggest
problem occurs with Capacitors or Transistors that are mounted straight
up. The amount of mass and distance from the board caused the leads
to break when the harmonics begin.

What I use is an encapsulating compound it does 3 major things
Transfers vibration and stress
Dissipates heat from components
Acts as an air tight barrier

Haven't had any problems since.
Derek B.




I think it really depends a -lot- on the solder used, how it was
soldered, etc. NASA and anything for the military gets tested to
death in vibration and G-force testing. Anything automotive gets
similar testing at a much lower level. Poor solder joints that will
last years in a small circuit on your test bench may last a day in
a car or a pinball game.

How many G's a board can take is going to depend a lot on how it is
supported. Same with vibration. Anything that sticks up high from
the board is going to be more susceptable to damage.

I think an important part of this is going to be isolating the
shock of the charge from the boards. I've seen wiring get
overlooked- short straight segments of solid wire are going to
transfer shock a lot more than very slack sections of very flexible
stranded wire. Test lead wire is meant to take a lot of bending
without breaking.

Steve Greenfield

--- Dave King <KingDWS@...> wrote:

> Hi
>
> This is a bit of a strange question. I keep stumbling into
> strange (but
> interesting)
> projects to play with.
>
> What is the maximum vibration level and/or G force standard smt
> or thruhole
> will tolerate ?
>
> I've been asked if I could figure out a electronic detonator for
> an
> airburst charge
> for snow guns. These are the guns/mortars they use to fire 4-8lb
> charges at
> potential slides to trigger them. The trigger will be a pic that
> simply counts
> and then fires a electric match after the preset delay.
>
> I'm hoping this will prove tremendously difficult so I get to
> "work" and
> have to blow
> things up all winter ;-]
>
> Tia
>
> Dave

_

Hi Dave,
Putting aside the degrees and the permits you should have
in order to start this project! Watch out what kind of batterys
you use. Alot of batterys have mercury in them even though
they are not called mercury. After several runs you will have
contaminated the area. Some capacitors have PCBs in them.


John

--- In Homebrew_PCBs@y..., Dave King <KingDWS@S...> wrote:
> Hi
>
> This is a bit of a strange question. I keep stumbling into strange
(but
> interesting)
> projects to play with.
>
> What is the maximum vibration level and/or G force standard smt or
thruhole
> will tolerate ?
>
> I've been asked if I could figure out a electronic detonator for an
> airburst charge
> for snow guns. These are the guns/mortars they use to fire 4-8lb
charges at
> potential slides to trigger them. The trigger will be a pic that
simply counts
> and then fires a electric match after the preset delay.
>
> I'm hoping this will prove tremendously difficult so I get
to "work" and
> have to blow
> things up all winter ;-]
>
> Tia
>
> Dave

Dave,
One time I went to the Microchip Master's Conference, a guy gave a talk
about how he makes fuses for high end fireworks with PICs. These PICs ride
in the fireworks and then detonate them at the right time. Pretty cool how
he does it actually. Anyway, he had the same issue, and he just potted the
whole thing and never had any problems after that.

*Brian

-----Original Message-----
From: Dave King [mailto:KingDWS@...]
Sent: Sunday, June 02, 2002 4:16 AM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] OT PCB Mounting loads


Hi

This is a bit of a strange question. I keep stumbling into strange (but
interesting)
projects to play with.

What is the maximum vibration level and/or G force standard smt or thruhole
will tolerate ?

I've been asked if I could figure out a electronic detonator for an
airburst charge
for snow guns. These are the guns/mortars they use to fire 4-8lb charges at
potential slides to trigger them. The trigger will be a pic that simply
counts
and then fires a electric match after the preset delay.

I'm hoping this will prove tremendously difficult so I get to "work" and
have to blow
things up all winter ;-]

Tia

Dave


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[Non-text portions of this message have been removed]

I have LITTLE experience with SMT, but it surely seems to ME that the COPPER
would peel loose from the "epoxy" way before the SOLDER would peel-loose from
the copper, if soldered properly! No? Jan Rowland

Not necessarily. If the solder joints are not quite good enough to
stand the shock of launch, you could experience brittle fracture.

Steve Greenfield

--- JanRwl@... wrote:

> I have LITTLE experience with SMT, but it surely seems to ME that
> the COPPER
> would peel loose from the "epoxy" way before the SOLDER would
> peel-loose from
> the copper, if soldered properly! No? Jan Rowland

=====
Steve Greenfield // Digital photo scanning, retouching,
Polymorph Digital Photography // and photomorphing to your specs.
253/318-2473 voice // We use the best little computer in
polymorph@... // the world, the Amiga!
http://www.polyphoto.com/ // Based in Tacoma, WA, USA

__________________________________________________
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Yahoo! - Official partner of 2002 FIFA World Cup
http://fifaworldcup.yahoo.com

At 03:39 PM 02/06/02 -0700, you wrote:

>Not necessarily. If the solder joints are not quite good enough to
>stand the shock of launch, you could experience brittle fracture.
>
>Steve Greenfield
>
>--- JanRwl@... wrote:
> > I have LITTLE experience with SMT, but it surely seems to ME that
> > the COPPER
> > would peel loose from the "epoxy" way before the SOLDER would
> > peel-loose from
> > the copper, if soldered properly! No? Jan Rowland

The board would be a very small single sided pcb about the size of a postage
stamp. If all smt is used the weight would only be a few 10's of grams. I was
assuming all the components would have been mounted on the "up" side so
any force would push the parts onto the board.

I posted the question onto another list and one of the fellows there evidently
designed something along the same use to detonate firework shells. Those get
fired off from a mortar which would have a more abrupt kick than what these
would..
I couldn't see anything producing enough G to peel off the copper.

Dave