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January 2007

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From:
"Wenger, George M." <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Wenger, George M.
Date:
Mon, 15 Jan 2007 09:07:04 -0500
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I agree with much of your data an observations but I ne
Richard,



I agree with much of your data an observations but I need to side with

Werner on your one statement.  Neither peel strength nor shear strength

are a relevant measure of solder joint reliability.  They may give you

measure of the strength of the solder joint at the moment when they were

tested but they are not a relevant measure of solder joint reliability.

If anything the mode of failure rather than the solder joint strength

might give you some indication that you could possibly have a

reliability issue.





Regards, 

George 

George M. Wenger 

Senior Principle FMA / Reliability Engineer 

Wireless network Solutions 

Andrew Corporation, 40 Technology Drive, Warren, NJ 07059 (908) 546-4531

[log in to unmask] 





-----Original Message-----

From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.

Sent: Monday, January 15, 2007 8:54 AM

To: [log in to unmask]

Subject: Re: [TN] SMD Capacitor Shear Strength



From data that I collected when performing solder paste evaluations for

standard 63/37 solder (four different evaluations, four different

companies, using only the data from the solder paste champions):

For an 0603 soldered to immersion silver finish, the shear forces

typically seen for an optimized solder joint are about 2100 grams as

measured using a Dage shear tester. For ENIG this drops to around 1800

grams. You will normally see a range of about 1900 to 2400 grams for

immersion silver finish. For ENIG the range drops to 1200 to 2100 grams

and the variance from the mean is wider. When measuring sheer strength

with the immersion silver finish, nearly all of the solder joints

literally sheared through or tore the pads off of the boards (about 25%

of the pads would release from the board before the solder joint

finished shearing through). For 0603s mounted on ENIG, more than 70% of

the solder joints fractured (broke off) before the solder joint sheared

through, and less than 2% of the pads sheared off. The time required to

shear through to release for the IAg solder joints averaged about 2.3

seconds, whilst the ENIG joints typically fractured at about 1.8

seconds, on average. This data was taken from 28 production board solder

test coupons (7 each of 4 different assembly numbers from two board

vendors) where solder balls were populated on the BGA pads, and 0402

caps, 0603 resistors, and 0806 resistors were populated but only one end

was soldered to the pads. The difference in force/time required to shear

0402s and 0603s was very similar, significantly more was required to

shear the 0806 packages. The force required to shear off the component

is NOT doubled when both ends are soldered, but I am not sure why. Some

of the 0402 caps did not have kapton tape covering one pad, so both ends

were soldered. The Dage shear strength required to shear them off was

about 2100 to 3000 grams. So I would suspect that for an 0603 component

with both ends soldered to IAg you should see a minimum of about 2200

grams, on average.



Peel strength is a more relevant measure of solder joint reliability

than shear strength in terms of reliability. I have not found a way to

easily perform peel strength on small components. The shear data does

provide a pretty good indicator of solder joint IMF brittleness.



-----Original Message-----

From: TechNet [mailto:[log in to unmask]] On Behalf Of Todd, Richard

Sent: Thursday, January 11, 2007 5:04 PM

To: [log in to unmask]

Subject: [TN] SMD Capacitor Shear Strength



I have a question for the oracle . . . 



Does anyone know what is the solder joint shear strength for an 0603

capacitor (assuming standard eutectic solder)?



 



Regards,



 



Rick Todd



Senior Engineer



Process Quality Engineering



 



Panasonic Automotive Systems Company of America



Division of Panasonic Corporation of North America



776 Highway 74 South, Peachtree City, GA 30269



770-515-1087 Direct



678-458-2887 Cell



770-486-2248 Fax



[log in to unmask] <mailto:[log in to unmask]> 



 





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