Prashant,
It depends.
How thick is your board?
What material is it made out of?
How many heat cycles has it seen?
What type of chip components - resistors, wire wound inductors, chip caps (there are two main types, CALCE has shown a difference between them)?
You need to:
1) Talk to your component manufacturer and find out what they say their parts can take
2) Attach strain gages and gather the data
Bev
RIM
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of prashant chopra
Sent: Wednesday, November 12, 2008 8:26 AM
To: [log in to unmask]
Subject: [TN] query -- solder crack
Hi,
I am working on a project and have an issue with PWB deflection during the FFT testing. I need your comments and suggestion on the query.
We are having FFT test points on the Bottom side of the board. There are 10 points localized in one area and the combined force of all the 10 pogo pins on the PWB is 3KgF. This PWB is held in position by 2 hooks (near to the FFT test points) and 2 snaps (these are on the other end) in the plastic base. We observed that there is deflection in the PWB when the pogo pins engage for the test purpose.
The issue is that we are having two to three 0603 components which are just about 70mils from these FFT test points on the bottom side.
And on the top side we have the two 0603 component which are sitting just on the top of the FFT test points at the bottom side where the pogo pins are getting engaged.
My concern is with this localized force and the PWB being deflected within the snaps, there could be a strain on the 0603 parts and they may be susceptible to solder cracking. And the 0603 parts which are exactly on the top have more risk of this solder crack.
We also have 0402 parts, but they are more than 300mils away from these FFT test points.
What are your thoughts on this? Can you let me know urgently as we are on critical path for this?
Thanks ,in advance to everyone for their valuable feedback .
Rgds
Prashant
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