polyimide stencils

I keep hearing about polyimide stencils, but what are they like in terms of registration and aperture accuracy?

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| I keep hearing about polyimide stencils, but what are they like in terms of registration and aperture accuracy? | Fraser-

We use polyimide stencils with great success for our prototype boards. They are cheaper and the accuracy/aperatures are the same as steel. We have had trouble with them breaking in production runs, even with our squeegee pressure reduced somewhat. Also, the printer is easier to set up for prototypes because the operator can see through it.

Ryan Jennens Phoenix Engineering Design, Inc.

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| | I keep hearing about polyimide stencils, but what are they like in terms of registration and aperture accuracy? | | | Fraser- | | We use polyimide stencils with great success for our prototype boards. They are cheaper and the accuracy/aperatures are the same as steel. We have had trouble with them breaking in production runs, even with our squeegee pressure reduced somewhat. Also, the printer is easier to set up for prototypes because the operator can see through it. | | Ryan Jennens | Phoenix Engineering Design, Inc. | Ryan: Have the price on these puppies come down? A while ago we compared plastic to metal with the following results.

SETUP - BIG + to plastic PASTE RELEASE - small + to plastic PRICE - push CLEANING - push DESIGN - push DELIVERY - push DURABILITY - BIG + to metal

As a result, we saw no big advantage to plastic. Dave F

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| | | I keep hearing about polyimide stencils, but what are they like in terms of registration and aperture accuracy? | | | | | Fraser- | | | | We use polyimide stencils with great success for our prototype boards. They are cheaper and the accuracy/aperatures are the same as steel. We have had trouble with them breaking in production runs, even with our squeegee pressure reduced somewhat. Also, the printer is easier to set up for prototypes because the operator can see through it. | | | | Ryan Jennens | | Phoenix Engineering Design, Inc. | | | Ryan: Have the price on these puppies come down? A while ago we compared plastic to metal with the following results. | | SETUP - BIG + to plastic | PASTE RELEASE - small + to plastic | PRICE - push | CLEANING - push | DESIGN - push | DELIVERY - push | DURABILITY - BIG + to metal | | As a result, we saw no big advantage to plastic. Dave F | chaps, thanks awfully for the info, but being British I'm not teribbly familiar with your American coloquialisms what exactly does "push" mean . Seriously - can you print a card stuffed with 20mil pitch and hold registration? Roughly how many prints can you get before breakage or damage occurs? Are there any high volume guys out there using these things ? pip pip.

Fraser.

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| | | | I keep hearing about polyimide stencils, but what are they like in terms of registration and aperture accuracy? | | | | | | | Fraser- | | | | | | We use polyimide stencils with great success for our prototype boards. They are cheaper and the accuracy/aperatures are the same as steel. We have had trouble with them breaking in production runs, even with our squeegee pressure reduced somewhat. Also, the printer is easier to set up for prototypes because the operator can see through it. | | | | | | Ryan Jennens | | | Phoenix Engineering Design, Inc. | | | | | Ryan: Have the price on these puppies come down? A while ago we compared plastic to metal with the following results. | | | | SETUP - BIG + to plastic | | PASTE RELEASE - small + to plastic | | PRICE - push | | CLEANING - push | | DESIGN - push | | DELIVERY - push | | DURABILITY - BIG + to metal | | | | As a result, we saw no big advantage to plastic. Dave F | | | chaps, | thanks awfully for the info, but being British I'm not teribbly familiar with your American coloquialisms what exactly does "push" mean . Seriously - can you print a card stuffed with 20mil pitch and hold registration? Roughly how many prints can you get before breakage or damage occurs? Are there any high volume guys out there using these things ? | pip pip. | | Fraser. | Fraser: This is as bad as telling a Brit to use a "home plate" shaped aperture. Sorry. A push can go either way. You can do 20 pitch nicely, but for how long, I'm not sure. There was a similar thread on Technet this past summer. I don't recall the details. Cheers Dave F

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| I keep hearing about polyimide stencils, but what are they like in terms of registration and aperture accuracy? | You are hearing about polyimide as in polyimide film as Kapton (TM Dupont). This material is the stuff of flex and rigid/flex circuitry. Typically, it is supplied in thickness from one to two mils. It is very delicate and is not tear resistant. Also, it ages poorly as it oxidizes (much as my once wonderful body - ladies only need inquire).

To achieve greater thicknesses, layers must be laminated using a thermoplastic (usually acrylic) adhesive also in the thicknesses indicated for Kapton. Both materials are inconsistent concerning thickness.

The adhesive often causes the problem of delamination that renders the stencil or circuit defective. Using these stencils has great advandages, as discussed by my never disgusting SMTeam mates, but long life is not one.

I can see clearly now - through a brownish/yellow haze. What's new in the PCB business.

Earl Moon

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| | | | | I keep hearing about polyimide stencils, but what are they like in terms of registration and aperture accuracy? | | | | | | | | | Fraser- | | | | | | | | We use polyimide stencils with great success for our prototype boards. They are cheaper and the accuracy/aperatures are the same as steel. We have had trouble with them breaking in production runs, even with our squeegee pressure reduced somewhat. Also, the printer is easier to set up for prototypes because the operator can see through it. | | | | | | | | Ryan Jennens | | | | Phoenix Engineering Design, Inc. | | | | | | | Ryan: Have the price on these puppies come down? A while ago we compared plastic to metal with the following results. | | | | | | SETUP - BIG + to plastic | | | PASTE RELEASE - small + to plastic | | | PRICE - push | | | CLEANING - push | | | DESIGN - push | | | DELIVERY - push | | | DURABILITY - BIG + to metal | | | | | | As a result, we saw no big advantage to plastic. Dave F | | | | | chaps, | | thanks awfully for the info, but being British I'm not teribbly familiar with your American coloquialisms what exactly does "push" mean . Seriously - can you print a card stuffed with 20mil pitch and hold registration? Roughly how many prints can you get before breakage or damage occurs? Are there any high volume guys out there using these things ? | | pip pip. | | | | Fraser. | | | Fraser: This is as bad as telling a Brit to use a "home plate" shaped aperture. Sorry. A push can go either way. You can do 20 pitch nicely, but for how long, I'm not sure. There was a similar thread on Technet this past summer. I don't recall the details. Cheers Dave F | Hi all, just to let you know a couple points from a stencil manufacturers perspective. - Plastic burns making it a difficult (not impossible) material to cut with a laser for fine pitch apertures. - Neither the stainless steel or plastic make up a significant part of our cost for making a stencil. In other words, the difference in price between a steel or poly stencil is negligible.

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| | | | | | I keep hearing about polyimide stencils, but what are they like in terms of registration and aperture accuracy? | | | | | | | | | | | Fraser- | | | | | | | | | | We use polyimide stencils with great success for our prototype boards. They are cheaper and the accuracy/aperatures are the same as steel. We have had trouble with them breaking in production runs, even with our squeegee pressure reduced somewhat. Also, the printer is easier to set up for prototypes because the operator can see through it. | | | | | | | | | | Ryan Jennens | | | | | Phoenix Engineering Design, Inc. | | | | | | | | | Ryan: Have the price on these puppies come down? A while ago we compared plastic to metal with the following results. | | | | | | | | SETUP - BIG + to plastic | | | | PASTE RELEASE - small + to plastic | | | | PRICE - push | | | | CLEANING - push | | | | DESIGN - push | | | | DELIVERY - push | | | | DURABILITY - BIG + to metal | | | | | | | | As a result, we saw no big advantage to plastic. Dave F | | | | | | | chaps, | | | thanks awfully for the info, but being British I'm not teribbly familiar with your American coloquialisms what exactly does "push" mean . Seriously - can you print a card stuffed with 20mil pitch and hold registration? Roughly how many prints can you get before breakage or damage occurs? Are there any high volume guys out there using these things ? | | | pip pip. | | | | | | Fraser. | | | | | Fraser: This is as bad as telling a Brit to use a "home plate" shaped aperture. Sorry. A push can go either way. You can do 20 pitch nicely, but for how long, I'm not sure. There was a similar thread on Technet this past summer. I don't recall the details. Cheers Dave F | | | Hi all, just to let you know a couple points from a stencil manufacturers perspective. | - Plastic burns making it a difficult (not impossible) material to cut with a laser for fine pitch apertures. | - Neither the stainless steel or plastic make up a significant part of our cost for making a stencil. In other words, the difference in price between a steel or poly stencil is negligible. | | thanks, but if you use the correct laser you can cut real sharp apertures easily as good as stainless down to fine pitch. What worries me is that if one has a dense board such that a lot of material is removed on the stencil, will the REGISTRATION hold up to heavy use. As we are doing trials now I'll let you guys know how we get on. cheers ! |

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| | I keep hearing about polyimide stencils, but what are they like in terms of registration and aperture accuracy? | | | You are hearing about polyimide as in polyimide film as Kapton (TM Dupont). This material is the stuff of flex and rigid/flex circuitry. Typically, it is supplied in thickness from one to two mils. It is very delicate and is not tear resistant. Also, it ages poorly as it oxidizes (much as my once wonderful body - ladies only need inquire). | | To achieve greater thicknesses, layers must be laminated using a thermoplastic (usually acrylic) adhesive also in the thicknesses indicated for Kapton. Both materials are inconsistent concerning thickness. | | The adhesive often causes the problem of delamination that renders the stencil or circuit defective. Using these stencils has great advandages, as discussed by my never disgusting SMTeam mates, but long life is not one. | | I can see clearly now - through a brownish/yellow haze. What's new in the PCB business. | | Earl Moon | Earl,

Just to bring you up todate, the polyimide we use for our stencils comes in thickness from 1 mil to 7 mil without adhesive layers. We also use a new product called Cirlex (a polyimide) that is available from 9 mil to 60 mil (in thickness) and is extremely easy to laser machine.

Hugh

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