Hi charming,
What you are proposing to build is quite difficult, because you only have 11 mils of 'meat' between holes. If you can drill without any glass fiber rip-outs —this can be done but only with frequently replaced new drills and very carefully controlled drilling parameters, you can avoid CAF.  CAF starts at the separations of glass fibers from the resin matrix due to 'aggressive' drilling.
Werner

 

-----Original Message-----
From: John Burke <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, Dec 24, 2009 12:55 pm
Subject: Re: [TN] Looking for advice on the design of 11mil DHW to DHW spacing.


Sorry that was 50 mil pitch....merry Christmas. ..8-)

John Burke <[log in to unmask]> wrote:

>Seen this tried before 5 years ago on internet switches cad risk is huge if you 
are running the 48 volt distributed power through that connector. In the testing 
I did on through hole at 25 mil pitch all failed through caf at 
humidity..temp..time 85 85 1000 hours.
>
>Charming Chan <[log in to unmask]> wrote:
>
>>Hello All, 
>>
>>Our connector supplier gave us a presentation and proposed us to use their SAS 
connector, which is 31mil pitch design with 16mil press fit hole. The drill bit 
is supposed to use 20mil, then the drilled hole wall to drilled hole wall 
spacing is only 11mil. I'm quite concerned on the CAF risk and the pcb 
fabrication quality(plating wicking, glass fiber cracking, etc.) on our 4.0mm 
thick backplane.
>>
>>This SAS connector is supposed to be used on high reliability storage server, 
so I'm looking for your advice on this. Thank you all.
>>
>>
>>Best Regards
>>Charming Chan
>>
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