Screen Printing Adhesive on Mixed Technology Boards

John, To answer your question, we have a number of customers that are using this process, Pumpprinting very successfully! If you would like to contact myself I can provide you with some very good references that will be able to answer all your questions. I can tell you that the cycle time is typically less than 30 secs per board no matter if it is 1000 or 10,000 dots that need to be put down. The cleaning of the stencils is a matter of contacting your adhesive material supplier and finding one that will work in your cleaner. In fact we have a some customers that are using their cleaner for both the paste and the adhesive stencils with no problems reported. As for HASL boards, our customers currently find no issue with using this type of finish on the boards.

Please feel free to contact myself or any of the other Applications Engineers to discuss your process more in detail.

Jerry Hingtgen Applications Eng, DEK USA 908-782-4140

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John,

I have seen process mixed technology in customer site.Now they dont use wave but they print paste through hole components.It is good and fast but it did take a time when they found a right paste to do that.Stencil is plastic and aprox.3mm(3000um)thick.If you go that way it will not be easy to find a right solderpaste. Regards, MDR

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John where in the world are you based?

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HAS ANYONE HAD EXPERIENCE WITH THIS PROCESS? => We print glue with a thick stencil on one product. Although it works �correctly�, we don�t like it because the process flow is goofy. So on a high mix line, it ends-up being a burden.

Also, there is no rocket science behind making the stencils for this process.

We are not experts in this, but we feel that it is difficult to control glue release. The issues appear to be: * High aspect ratio. * Curing of glue through the production run.

HOW DOES IT COMPARE TO DISPENSING? => It is way: * Cheaper from a capital expense stand-point * Faster board mateial deposition cycle time * Less controlable * Slower turn job turns [but that probably doesn't matter because your P&P will be the long pole] * Lower flexibility [but that probably doesn't matter because you're setting this line for a particular product]

Search the fine SMTnet Archives for a comparison of using a dispenser and a printer to deposit paste. [Even though you're doing glue, many of the points of comparison carry through.]

ARE THE STENCILS DIFFICULT TO CLEAN? No, if you don�t let the glue cure, as with metal glue stencils.

SHOULD THE HASL BOARD SEAL WELL ENOUGH TO THE STENCIL? Yes

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We've used pump print stencils on and off for a couple of years now, and experimented with various epoxies. One supplier gave us some samples to try and we found that the adhesive they supply for normal metal stencil printing didn't work well with the thicker plastic stencil. However, we found quite by accident that a product they had developed specifically for pin transfer application worked perfectly with the pump print process.

Even so, the main problems concerning pump printing remain cleaning and keeping clean the stencil after and between uses, and the amount of adhesive which gets wasted and thrown away at the end of the run.

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