Walter Horaud,

For information on BGA's solder masks design rules, I suggest you hit the
following websites:

Amkor:
http://www.amkor.com/customer_center/assembly_and_test/white_papers/index.ht
m

TI: TMS320C6000 BGA Manufacturing Considerations (PDF: 84 KB) (You'll have
to get to TI's website)

Motorola:
http://www.mot-sps.com/cgi-bin/get.pl?/books/apnotes/pdf/an1231*.pdf

In reviewing these documents, they are pretty consistent with Steve
Gregory's reference.

Good Luck

Lee Whiteman
Senior Manufacturing Engineer
ACI / EMPF
Telephone: (610) 362-1200; Ext. 208
FAX: (610) 362-1290
E-Mail: [log in to unmask] <mailto:[log in to unmask]>


> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Horaud, Walter
> Sent: Wednesday, September 06, 2000 12:43 PM
> To: [log in to unmask]
> Subject: [TN] Solder mask problems
>
>
> Thechneters,
>
> I'd like to know if there are special design rules for the solder mask on
> PCB.
> Most of PCBs I have seen have pads surrended with a gap and solder mask.
> In our case I have got a PCB with solder mask on the periphery of BGA pads
> (to prevent bridging according to the customer).
> It seems to me that the solder mask on the periphery of pads is not so
> efficient as expected to prevent bridging and it seems to be also
> responsible of the poor mechanical properties of the joint.
> Does anybody have experience with this weird technique (solder mask on the
> periphery of pads)?
>
> Thanks in advance,
>
>
> Walter Horaud
>
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