are you also measuring pressfit insertion and extraction force (as a
predictor of gas tight joint)?

At 08:37 AM 1/17/2006, Ofer Cohen wrote:
>Dwight,
>I used to send the data as you describe. For the matter effect, the
>parameters were extracted from the connectors' data sheets. However,
>time after time we received from various manufacturers the request to
>give them the final hole diameter and tolerance (+/-2 mils), and the
>minimum copper thickness (25 to 50 micron). Hence, to avoid
>interactions, we changed the callout to the vendors' request. We are
>monitoring the outcome through micro sections.
>
>Regards
>Ofer Cohen
>Manager - Quality Assurance and Reliability
>SIEMENS COM FN A SB
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Dwight Mattix
>Sent: Tuesday, January 17, 2006 17:23
>To: [log in to unmask]
>Subject: Re: [TN] Drill and plated hole callouts
>
>I concur with Werner with the key exception being for pressfit connector
>holes.
>
>Our experience dictates that we specify pressfit holes with
>a) manufacturer's exact drill size, (provides the ideal "Goldilocks"
>envelope for the needed copper deformation -- not too much to crack
>copper,
>not too little and not acheive gas tight joint)
>b) minimum copper thickness, (we spec 0.0012" min for older 2.5 mm pitch
>and 0.001" min for 2.0mm pitch pressfit) and
>c) minimum finished hole size (too small will increase insertion forces
>overwhelming the insertion press or causing pins to "Z-kink" onto pwb
>surface).
>
>These factors combine to ensure a reliable gas tight joint without
>excessive insertion forces or excessive holewall deformation (leading to
>post separation or barrel cracking).
>
>It all starts with using the proper (precise) drill size.  The connector
>mfg's recommended drill size is the paramount concern.
>Ergo, the exception where drilled hole size should be specified.
>
>my $.02,
>dw
>
>
>At 05:41 PM 1/16/2006, Werner Engelmaier wrote:
> >Hi Bob,
> >The call out of finished hole size is an anachronism left over from the
> >through-hole technology era. In modern high-density PCBs you should
> >specify the
> >drilled hole size (no tolerance) with a minimum plating thickness in
>the
> >hole to
> >be verified by cross-sectiong of coupons.
> >The reliability of your vias depends on PCB thickness, drilled hole
>size, Cu
> >plating thickness, Cu plating quality (verified by testing co-plated
>mandrel
> >foils for tensile strength and ductiolity--not elongation). Your friend
>is
> >right,
> >electrical test is not enough. You should have coupons either IST or
> >HATS-tested. This will be even more important with LF-soldering
> >temperatures. You then
> >might want to specify not only Tg, but Td and CTE(z) as well.
> >
> >Regards,
> >Werner Engelmaier
> >Engelmaier Associates, L.C.
> >Electronic Packaging, Interconnection and Reliability Consulting
> >7 Jasmine Run
> >Ormond Beach, FL 32174 USA
> >Phone: 386-437-8747, Fax: 386-437-8737, Cell: 386-316-5904
> >E-mail: [log in to unmask], Website: www.engelmaier.com
> >
> >
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