TECHNET Archives

June 2018

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Tan Geok Ang <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Tan Geok Ang <[log in to unmask]>
Date:
Wed, 6 Jun 2018 23:20:32 +0000
Content-Type:
text/plain
Parts/Attachments:
text/plain (53 lines)
Hi Steve,
As you stated shimming is one of the methods and another way is to reduce the stencil opening dimension/ solder paste volume but this will lead to whether is it a cleaning or non cleaning process. If cleaning process, whether how effective it is.

GA Tan


________________________________

From: Steve Gregory <[log in to unmask]>
Date: 7 June 2018 at 6:14:10 AM SGT
To: [log in to unmask] <[log in to unmask]>
Subject: [TN] High Ball Count BGA's with heavy heat spreader

Hi All,

I've been one of the lucky ones who hasn't had to deal with high ball count
BGA's (1900+ balls) until now. I have a 1936-ball BGA that we are looking
to assemble. I was able to get a couple of mechanical samples so that I
could use them to dial my reflow profile in. When I got them, if I said I
was surprised, that would be an understatement. This thing weighs close to
an ounce with the heat spreader (23.133-grams):

http://stevezeva.homestead.com/1936_Ball_BGA_with_Heat_Spreader.jpg

So I remember reading threads on the Technet about shimming heavy, high
ball count BGA's in the corners with something to keep the weight from
squishing the balls out and causing shorts, I know that can happen because
I have seen it on 1152-ball CBGA's from Xilinx.

Is there anybody willing to share some tips about assembling these beasts?
At least I have a couple of mechanical samples I can play with before I
dive in with live product....these are spendy.

Steve

--



This email and any attachments are only
for use by the intended
recipient(s) and may contain legally privileged,
 confidential, proprietary
or otherwise private information. Any
unauthorized use, reproduction,
dissemination, distribution or other
disclosure of the contents of this
e-mail or its attachments is strictly
 prohibited. If you have received
this email in error, please notify the
 sender immediately and delete the
original.

ATOM RSS1 RSS2