[SI-LIST] Re: Search for the paper about minimum BGA pad size in PCB

Dear Indrek,

Thanks for your comments.

"According to IPC-7351, pad size for 0.6mm BGA ball size should be 0.5mm
(about 20mil)".

Understand it now.

Have a nice day!
Best Regards,
Peter Pang

----- Original Message ----- 
From: "Indrek Rebane" <indrek@xxxxxxxxx>
To: <pangning2000@xxxxxxxxx>
Cc: <si-list@xxxxxxxxxxxxx>; <morris_yu@xxxxxxxxxxx>
Sent: Thursday, June 16, 2005 10:33 PM
Subject: [SI-LIST] Re: Search for the paper about minimum BGA pad size in
PCB


Dear Pang et al,

Pang Ning wrote:
> I encountered a problem about BGA pad size in PCB. The actual ball
> size is 0.6mm, and ball pitch is 1.0mm.

According to IPC-7351, pad size for 0.6mm BGA ball size should be 0.5mm
(about 20mil).

> But in this way the BGA pad size in PCB will be only 14mil.

I assume this is too small for given BGA, not for manufacture. In past I
have successfully done few designs using 0.5mm pitch BGA's with 0.2mm
pad size; boards were manufactured and are working without problems.
However in your case, pad size on PCB is about 30% smaller than on BGA
package -- not really an optimal solution.

Indrek

-- 
Indrek Rebane
Borthwick-Pignon OÃ, R&D
Riia 185, 51014 Tartu, Estonia
Phone: +372 7 302 641, Fax: +372 7 383 041

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