Taking advantage of the question regarding peel/bond strength, I would like
to ask a question on the same line, Surface Mount Pads, mainly dummy BGA
Pads, lift very easy during removal/cleaning of solder left after removing
BGA, & more with Lead free. This is a major problem today with BGA & Lead
Free. Question, Should be a requirement for BGA Pads [lead free PCBs] to
withstand a X amount of temperature during the removal of the solder? Does
dummy pads should be replaced if lifted? I personally do not see why should
we? They are not connected. Curiosity? What holds the SMT, BGA pads to the
surface of the PCB? Glue?
 
Regards from your,
Constantino J. González
President / Consultant Engineer
IPC-A-610 Committee Chairman

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-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Susan Hott
Sent: Wednesday, May 31, 2006 7:20 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Bond Strength -vs- Peel Strength

Franklin
One of my very favorite topics.  The bond strength for unsupported holes has
been around a verrrry long time.  Since the only circuit boards out there
were single sided.  

The need for a bond strength test for surface mount lands has been discussed
and there was a "Provisional" method out there for a while, but there were
too many unknowns to be able to make it work.  Since the "giant" copper pins
that were required by the method had heads that had a diameter larger than
some surface mount lands and smaller than others - there was no agreement on
the significance of this fact.  The pins were to be hand soldered so the
amount of solder in the joint was a concern.  Then there was the inability
to determine how low can you go in conductor width and expect the same
values for peel strength found in the various slash sheets to hold up for
pass/fail criteria.  Also a concern is the perpendicularity of the pin that
would have to be pulled.  

Soldering a wire into an unsupported hole is much simpler than trying to
solder a rigid lead to a surface mount land.

The specification does provide for peel strength testing, but requires it
only when foil is used on outer layers.  This is performed on 1/8 inch wide
strips of surface conductors - far from the geometries of surface mount
lands.

So, Franklin, what is your goal in wanting such a test?  

Susan Hott
President
Robisan Laboratory, Inc
6502 E 21st Street
Indianapolis, IN 46219

317-353-6249 phone
317-917-2379 fax

www.robisan.com




-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]]On Behalf Of Franklin D
Asbell
Sent: Wednesday, May 31, 2006 9:00 AM
To: [log in to unmask]
Subject: [IPC-600-6012] Bond Strength -vs- Peel Strength


I'm curious what everyone's thoughts are regarding relevancy of IPC 6012
Table 4-4 Bond Strength (IPC-TM-650 2.4.21) testing are? Wouldn't peel
strength (IPC-TM-650 2.4.8) testing be a better test to perform?  Or at a
minimum, change the test to include smt lands instead of unsupported holes.



Franklin