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Circuit Card Assembly Molding

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#64016

Circuit Card Assembly Molding | 24 March, 2011

Hi,

I have a 2.75" x 1" x 0.027"thick CCA with SOIC16W and QFN56 as well as some 0201's, 0402's and QFN16 Components that are to be enclosed via molding process.

Is there any Insert Moling, Over Molding Circuit Card Assembly Guidelines out there from IPC or other electronics org that we can use as reference. We plan to aply Conformal Coating, Encapsulation or Potting then pre-molding and then the final Molding. But I also want to get idea if the conformal coating is a good part of the process for this or must be eliminated?

thanks for your inputs.

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#64018

Circuit Card Assembly Molding | 24 March, 2011

You're correct. There's no point in conformal coating a board that you intend to pot.

We're aware of no IPC [or IPCish] standards or guidelines for potting or encapsulation. We'd guess that materials and / or equipment suppliers would be the best place to start.

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#64051

Circuit Card Assembly Molding | 29 March, 2011

I agree with Davef, there is no point in conformal coating the assembly before potting.

I am also not aware of any IPC standard for potting or encapsulation.

If you would like to discuss equipment for potting/ encapsulation, we would be happy to discuss our solutions with you.

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#64064

Circuit Card Assembly Molding | 31 March, 2011

I disagree with the others about conformal coating before potting. Some of the softer urethane potting compounds can absorb water leading to caustic nastiness in the voids under the parts. Conformal coating can help fill/seal the voids and keep the nastiness out.

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#64073

Circuit Card Assembly Molding | 1 April, 2011

thanks for all your replies.

we tried running our beta runs and have lots of issues. first our molding process which was set to 450'F temp at 1200 PSI smashed the circuit card components and penetrated the epoxy compound we used to encapsulate the Circuit Card Assy. we are also finding voids in our epoxy compound during encapsulation and we believe that we do not have the right compound for the application of molding process. talked to couple of compound manufacturers and still waiting for their reply for the right compound that will protect the CCA during the molding process.

does anyone here knows or tried encapsulating or potting pcb assembly then molding them?

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#64083

Circuit Card Assembly Molding | 5 April, 2011

I would look into Low Pressure Overmolding for this application. Seems like it would be a good fit and would seem to be far less costly. Check out: http://moldmanmachines.com/

I have no stake in the above company, but I have researched the process and it's pretty slick.

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