gussy:
Good to know.Now to see if Applied Electronics ship to Australia!
Yes. Applied Electronics ships world wide. See the following link for details:
http://www.applied-electronics.com/inde … aux_page=2
AE
Not long ago Makezine posted this link for PCB stencils:
http://www.lasercutpcbstencils.com/
They use “Polymeric Stencil Materials”. Anyone know where I could get some? I have access to a laser cutter at work and would like to make my own stencils. I guess I could try kapton instead, but I’m thinking that this material would be better. But that is just a guess.
yzf600:
Not long ago Makezine posted this link for PCB stencils:http://www.lasercutpcbstencils.com/
They use “Polymeric Stencil Materials”. Anyone know where I could get some? I have access to a laser cutter at work and would like to make my own stencils. I guess I could try kapton instead, but I’m thinking that this material would be better. But that is just a guess.
Ha, polyethylene is a type of “polymeric” material. Their definition of material is useless.
I would almost bet they are using Kapton, which is used in flex circuits. As a matter of fact…notice the pictures in their tutorial are in black and white. They do not want any potential competition to know the material is a brown color…indicating Kapton. I’m almost positive the material is Kapton.
The advantage of Kapton is what happens when hit with a laser (considering enough power of course). Kapton will just turn to “ash”, and does not melt. Most other materials melt and leave a “flash” edge where they are cut. The disadvantage is that Kapton is not 100% stable with relation to moisture. Humidity will cause it to change dimensions with the moisture level. This is not a problem if used at a consistent humidity level, or if not using fine pitch parts. The larger the stencil, the more offset seen when it changes dimensions.
As for making your own, there are some things to look at. First you need to know the beam width of the laser. This is the most important item. You must subtract the width from the gerber. Second the laser software must be able to exactly duplicate the dimensions perfectly (not as important on larger parts).
I really feel, with all that must be done…it is really cheaper to go through one of the other services listed above. There is a “technique” to getting a stencil right. If you stretch or shrink the stencil much (in the software)…it is useless…and Kapton is not cheap. I know…I found the material for a friend.
James L
Just as a note…Kapton (polyimide) would be considered a “polymeric” material.
James L
BTW - anyone know how stainless steel stencils are made? How do they get the ultra small apertures? I’ll fathom a guess that it involves photo resist and chemical etching.
yzf600:
BTW - anyone know how stainless steel stencils are made? How do they get the ultra small apertures? I’ll fathom a guess that it involves photo resist and chemical etching.
This depends…
The stencil manufacturer we use has two methods (for cutting). Chemical etch and laser. They use a very expensive industrial laser with a near microscopic beam, and cut the apertures. They also do chemical etching, but the apertures have different properties depending on the method.
There is also a plating method to make a stencil…but those are very expensive. They basically build up a stencil from a template sheet…with electroplating. We have never had the need for such a nice stencil, although I would love to try one. It has been said a “build up” stencil will release solder the best of any stencil made.
James L
yzf600:
Not long ago Makezine posted this link for PCB stencils:http://www.lasercutpcbstencils.com/
They use “Polymeric Stencil Materials”. Anyone know where I could get some?
It is mostly likely Kapton.
I have access to a laser cutter at work and would like to make my own stencils. I guess I could try kapton instead,
.
However be warned that Kapton is a little dirty. It produces black flakes that will make your machine and surrounding area dirty and hard to clean. Also you need to clean Kapon afterwards with alcohol and have a lot of patience. In case of fine ICs the likeyhood of damage is high with capton during cleaning. However in case of Mylar you do not really need cleaning. My personal preference is Mylar.