Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


voids at solder joint of chip

Wister

#17167

voids at solder joint of chips | 10 August, 2001

There are lots of voids at solder joint of chips,the thickness of multilayer pcb is 3.2mm,top side have lots of chip component and bottom side has several BGA and QFPs.For top side profile,the preheat time is about 100s,soak time is about 75s,time over 183 is 70s. How to optimize the profile if other factors could not be considered? Anyone show me the direction will be very appreciated. Thanks,

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Hussman

#17171

voids at solder joint of chips | 10 August, 2001

Hey Wister,

Assuming you are talking about BGA voids, and you just want to try and optimize your profile, you could try a "straight ramp profie". This is where the soak temp is constantly being elivated until you hit reflow. I find this helped me out in the past.

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#17176

voids at solder joint of chips | 10 August, 2001

More and more pople are seeing voids in solder connections other than BGA balls than ever before. Thats because they never looked [never had the means to look] before. Now, they can't stand it and, like that zit that their mother told them not to mess with, they looking at solder connections other than BGA balls with their xray machines.

Your voids are a process indicator. So, it's reasonable that you would want to better understand their source and to try to eliminate their occurance.

These's 200+ postings in the fine SMTnet Archives that relate to void*. Check 'em aut. They will help you understand your profile better and get you on the path to void redemption.

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Boysen

#17196

voids at solder joint of chips | 14 August, 2001

Are you using a water soluble paste? Older generations of water soluble paste are notorious for voiding. Some of the new generation water soluble fluxes allow a much wider process window.

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