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HASL Plating Thickness


CL

#3673

HASL Plating Thickness | 28 June, 2000

Does anyone know what the min-max plating thickness for HASL is? Is there a specification that defines this requirement? We have had problems with PCB's that have excessive solder plating on the pads. This wreaks havok with our QFP's. Any help would be greatly appreciated

Thanks In Advance

Christopher Lampron

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Brian W.

#3674

Re: HASL Plating Thickness | 28 June, 2000

HASL plating, by its very nature, is inconsistent in terms of thickness and consistency. The plating varies from spot to spot on the pad, as well as pad to pad. This will wreak havoc on your screen printing process and your placement. From talking to board houses, and monitoring their product quality, I have found that the HASL process has a very low Cp and Cpk.

If you are having problems with the plating, I would recommend going to an OSP or immersion gold plating on your boards. These finishes provide a much flatter surface on the pads, reducing many of the issues you are dealing with. In addition, anytime I have ordered OSP, I have gotten a lower price than HASL boards.

Good luck, Brian W.

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#3675

Re: HASL Plating Thickness | 29 June, 2000

Hello Christopher I don't know if there is any kind of official standard but I can tell you that the HADCO DFM manual specifies a nominal thickness of 50-1500u" with an option for 100-1000u" and the Merix DFM manual specifies 30-200u" Our boards (from a different major FAB house) average 500u" with an as measured range of 300-800u" Too thick and you'll have problems with your stencil gasketing and paste release, among others. Too thin and the result will be an unsolderable layer of intermetallics. Search the archives for much more. John Thorup

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