TECHNET Archives

September 1997

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:
David D Hillman <[log in to unmask]>
Reply To:
TechNet Mail Forum.
Date:
Fri, 19 Sep 1997 07:21:14 -0500
Content-Type:
text/plain
Parts/Attachments:
text/plain (93 lines)
Hi Harasha -

"a) Why this colour change?"

**My guess would be that the nickel has diffused into the gold or even to
the point of reaching the gold finish surface. You can verify this by
conducting a electron microscopy analysis.

"b) What are the standard pre-solderability activities to be followed for
above type of boards?"

**Sorry, but "standard activities" will depend on your process. Some folks
bake to remove moisture, some have adhesive cures prior to soldering
operations, etc. You need to work with your PWB vendor to procure a
solderable finish that will be robust enough to withstand your processing
recipes.

"c) What is the recommanded Gold and Nickel thickness required for boards
with BGA?"

**What I have seen most often quoted is 5 microinches of gold over 100-200
microinches of nickel with the quality of the nickel finish equally as
important as the gold finish.

"d) What are the possible reasons for failure of solderability in BGA
holes?"

**See what the electron microscopy analysis yields!

Good Luck.

Dave Hillman
Rockwell Collins
[log in to unmask]





[log in to unmask] on 09/16/97 04:25:43 PM

Please respond to [log in to unmask]; Please respond to [log in to unmask]

To:   [log in to unmask]
cc:    (bcc: David D Hillman/CedarRapids/Collins/Rockwell)
Subject:  [TECHNET] Solderabilty problem in BGA




Dear Technet users,

We are facing solderablity problem with 6Layers, 0.78mm, 0.3mm(10mil)
finish hole size(BGA HOLES) with ELECTROLESS NICKEL/IMMERSSION GOLD.
01. The board when passed through the assembly line without pre baking,
have Blow holes problems in the BGA holes.
2. The boards after pre baking at 120 degree centigrade for 3 hrs had no
blow holes in BGA holes but the colour of GOLD changed to Reddish-Brown.
Will anyone can highlight on....
a) Why this colour change?
b) What are the standard pre-solderability activities to be followed for
above type of boards?
c) What is the recommanded Gold and Nickel thickness required for boards
with BGA?
d) What are the possible reasons for failure of solderability in BGA holes?
Thanks in advance.
Harsha Adya.
##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following
text in the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
additional information.
For the technical support contact Dmitriy Sklyar at [log in to unmask] or
847-509-9700 ext.311
##############################################################

##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information.
For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311
##############################################################


ATOM RSS1 RSS2