Hi Chis,
What do you mean be "non-preferred Pad terminology"? Everybody I know of calls it 'pad cratering.'
Werner
Future workshops:
Pb-Free Soldering Processes: Survival, Quality, Reliability—PROBLEMS & SOLUTIONS, March 3, IPC/JEDEC Santa Clara, CA
Solder Joint Reliability: Part 1—Solder Joint Reliability Fundamentals, March 29, IPC EXPO/APEX Las Vegas
Pb-Free Soldering Processes: Survival, Quality, Reliability: PROBLEMS & SOLUTIONS, March 30, IPC EXPO/APEX Las Vegas
-----Original Message-----
From: Chris Mahanna <[log in to unmask]>
To: [log in to unmask]
Sent: Mon, 5 Jan 2009 12:18 pm
Subject: Re: [IPC-600-6012] Pad to trace interface on BGAs.
Mike,
Excellent. Thank you. I would have never found it. I was looking under
cratering and land. Not that I'm griping (because I wasn't on the call, or in
the meeting to help), but why did T-50 choose to use the non-preferred Pad
terminology?
Chris
-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Green, Mike
Sent: Monday, January 05, 2009 11:46 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Pad to trace interface on BGAs.
IPC T-50, Revision H, Terms and Definitions for Interconnecting and Packaging
Electronic Circuits, has addressed this term.
Pad Cratering 96.2176
A separation of the pad from the printed board resin/weave composite or within
the composite immediately adjacent to the pad as a result of mechanical and/or
thermal20stress.
Mike Green
Electronic Packaging Design
LMCO-Sunnyvale
408-743-1635
One Corporation, One Team
"Those who have nothing to follow must lead." M. Green, 2008
-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Chris Mahanna
Sent: Tuesday, December 30, 2008 8:53 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Pad to trace interface on BGAs.
Tino,
Cratering is your culprit, and as pretty common. You shouldn't have much
trouble finding help. Werner would top my list of the non-free variety.
IPC-7095B is an excellent source of general info.
Without changing the design, "better" laminate material and cool-down will
probably fix you up.
However, I'll bet you a nickel that this is a foil laminated board and that if
you tested peel strength (after assembly reflow excursions) it would be 0.5 to
0.7N/mm (much lower than it should be). In other words, the board fabricator
might bear some responsibility. We find peel strength to be an good, cheap tool
for monitoring adhesion/cohesion degradation at the surface. The military still
requires peel testing as periodic conformance (albeit, not after convection
reflow, or at elevated temp). 6012 voted against it.
BTW, does anyone have an action to take "cratering" to T-50?
Happy New Year to all.
Chris
Chris Mahanna
Robisan Laboratory Inc.
6502 E 21st Street
Indianapolis, Indiana 46219
317.353.6249
-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Constantino
Gonzalez=0
ASent: Monday, December 22, 2008 10:04 PM
To: [log in to unmask]
Subject: [IPC-600-6012] Pad to trace interface on BGAs.
Importance: High
Hello, I have a customer with a problem described below, Could you PLEASE HELP
ME?
The problem is that several boards are being returned to the plant after failing
in the field.
After Failure Analysis the engineers have found that the reason for the failure
is that one of the traces of the PCB connected to a BGA pad is becoming cracked
(Micro crack at BGA Pad AJ29 in the corner of the BGA) as showed in picture
below:
image001.gif image002.gif
They have concluded that Copper qty at PCB layer is not enough to support the
normal Mechanical Stress in the unit chassis during the Transportation resulting
in the trace and pad crack.
Based on Jedec JESD22B113 standard, they are suggesting that the customer change
design on the traces connected to BGA pads as shown below: Does the
IPC7351 suggest anything related to this...
image003.gif
I have not heard before about this type of junction from traces to pads, and
being honest I did not know the Jedec STD mentioned.
Have any of you ever heard about this special union from traces to BGA pads to
avoid stress or any other recommendation to reinforce trace to pad joints?
Could you please enlight me with your thoughts or opinions about this issue?
Regards.
Constantino J. González, ACME, INC. - GALUSAMEX REPAIR Co.
President / Consultant Engineer - Official IPC MASTER INSTRUCTOR - IPC
-A-610
Committee Chairman USA Cell Phone: 605-381-5963 - Mexico Cell Phone: 55-2709 -
6392 - <mailto:[log in to unmask]> [log in to unmask] or <mailto:[log in to unmask]>
[log in to unmask]
Does your Company need Rework, Repair or Inspection of Electronic Assemblies
Services.
Do you have too much Rework, Scrap or Rejects from your Customer.....Call us, We
can help!
GALUSAMEX REPAIR Co.
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