Amol -
We've had BGA pad bond strength/peel strength testing performed for us by
outside labs ( per IPC TM 650, section 2.4.21.1) when we've had suspicions
of incoming problems. We've found significant variability between laminates
and PCBs for the same design. I don't recall the specs but I do remember
that a bond strength less than ~500 psi was considered borderline/low.
Thanks,
Cheryl Tulkoff
Senior Reliability Engineer
Phone:(512) 683-8586
Fax: (512) 683-8847
National Instruments
11500 N. Mopac Expressway
Building C
Austin, TX 78759-3504
"Kane, Amol
(349)"
<akane@HARVARDGRP To
.COM> [log in to unmask]
Sent by: Leadfree cc
<[log in to unmask]
> Subject
Re: [LF] Copper Pad Peel Strength
08/25/2006 06:49
AM
Please respond to
"(Leadfree
Electronics
Assembly Forum)"
<[log in to unmask]
>; Please respond
to
"Kane, Amol
(349)"
<akane@HARVARDGRP
.COM>
Thank you Rex, I wasn't comparing the bare metal peel strength with the one
after the process. But if there is a standard out there, we can at least
know the variability in the peel strength for unprocessed incoming boards
and flag our supplier about this. As a process engineer, I will want to see
if there is any external variability before I go in and change my process.
Regards,
Amol Kane
M.S (Industrial Eng.)
Process Engineer
Harvard Custom Manufacturing, Inc.
941 Route 38 Owego, NY 13827
Phone: (607) 687-7669 x349
[log in to unmask]
www.harvardgrp.com
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Rex Waygood
Sent: Friday, August 25, 2006 7:43 AM
To: [log in to unmask]
Subject: Re: [LF] Copper Pad Peel Strength
I am not sure if this helps.
We had complaints that a compliant assembly was having pads lift off at
the customers when their production soldered to the pads.
We did a series of experiments changing the soldering technique and
measuring the peel strength of the pads. Changing the hand soldering
technique, the alloy and the laminate material had very significant
affects upon the peel strength. I would therefore think it difficult to
relate bare material peel strength to the peel strength you would obtain
after your process. Our experience showed that different processes
caused the largest variation in peel strength.
We also sent someone to help the customer improve their soldering
process.
Regards
Rex
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Kane, Amol (349)
Sent: 25 August 2006 12:30
To: [log in to unmask]
Subject: [LF] Copper Pad Peel Strength
Dear Technetters,
We are having instances where copper pads (Under BGAs) are being lifted
off ENIG Boards almost too easily during rework. We use the same thermal
profile on each board (for the same component removal) and only some
show this phenomenon. Is there a test or standard to test the copper
adhesion @ incoming to see whether it's the fab (i.e. are the boards
coming to us with poor copper adhesion strength to being with) or the
process that's doing this. The board is heated upto 120 C when the
component is reflowed for removal. Also, is there data to show the
decrease in Cu adhesion strength with temp?
Thanks,
Amol Kane
M.S (Industrial Eng.)
Process Engineer
Harvard Custom Manufacturing, Inc.
941 Route 38 Owego, NY 13827
Phone: (607) 687-7669 x349
[log in to unmask]
www.harvardgrp.com
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