Using SMT to mount rider cards to mother boards

Has anyone had any experience in using SMT to mount an organic (FR-4, Getek) rider card onto an organic (FR-4, Getek) mother board? By SMT I mean the attachment of the rider card would be through pads directly to pads on the mother board.

Thanks,

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| Has anyone had any experience in using SMT to mount an organic (FR-4, Getek) rider card onto an organic (FR-4, Getek) mother board? By SMT I mean the attachment of the rider card would be through pads directly to pads on the mother board. | | Thanks, | | I, and companies I've worked with, have done it using quasi-BGA device technology, add on "clips" (many years ago), and/or "half hole" castellations (also dating back sometime) defined after routing complete through holes.

Lately, I've been "balling" bottom side PCB rider cards, as you call them appropriately, micro-stenciling solder paste, and reflowing on a rework/ repair machine. I also do this in production using "normal" reflow operations.

Earl Moon

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| Has anyone had any experience in using SMT to mount an organic (FR-4, Getek) rider card onto an organic (FR-4, Getek) mother board? By SMT I mean the attachment of the rider card would be through pads directly to pads on the mother board. | | Thanks, | Len,

I have to answer your latest here as I have no more time. We are doing "our" version of BGA's using FR-4, 6 layer boards that are 2" by 3". I have done the castellations you mentioned with smaller sizes carefully matching material TCE's, as you know, ensuring only FR-4 matching, polyimide matching, CIC matching, ceramic matching, etc. Plus, watch the copper amount as it expands more than the resin/glass material.

It really isn't difficult. I would suggest you look at add on "lead/clips" instead of castellations to ensure compliance when needed. Also, keep the rider cards a little thicker than say .016" to ensure a good solder fillet when using castellations.

Enjoy,

Earl Moon

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