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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


BGA Underfill

morefun

#17328

BGA Underfill | 23 August, 2001

Some of our other divisions have had to do epoxy underfill with BGA devices to obtain adequate reliability for aerospace applications. Are there any special layout considerations required to ensure that we can do underfill if we deem it necessary during our testing? Obviously, we don't want to have to redesign the board later to support this....

What is the cost impact of doing epoxy underfill?

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#17337

BGA Underfill | 23 August, 2001

We never underfill BGA, but then again our products are not blasted into space.

Certainly you need to provide enough room for the dispense head to move around the component in the pattern appropriate for the underfill you plan to use. Probably more important is the match between the underfill and the surface roughness of soldermask to provide adequate strength [maybe figure this out sooner rather than later].

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morefun

#17343

BGA Underfill | 23 August, 2001

Thanks Dave - I am overwhelmed and appreciative of all the posts that you reply to, it is amazing!!!

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#17344

BGA Underfill | 23 August, 2001

Yeh, I gotta quit this shit.

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Sean D

#17377

BGA Underfill | 27 August, 2001

Hey guys,

Given the fact that i know very little about your product I would say put the burden on the apps engineers at Speedline-Camalot(www.speedlinetechnologies.com). General rules of thumb may not apply depending on your material selection and product. If you send samples, they will analyze them, make recommendations, and be able to generate some quantitative data if you wish to persue testing. Then you can start dealing with your cure issues.

One technology for underfill curing you may wish to examine would be Variable Frequency Microwave (VFM) curing. If you are experiencing issues with convection, VFM may be able to drastically reduce your cycle time and the stress effect on the product depending again on your material selection. Lambda Technologies (www.microcure.com) has plenty of data on VFM and will also run applications evaluations should you wish to provide samples. They also have a Forum at the HDI Expo in Phoenix the week of September 23rd (www.hdiexpo.com)

Please feel free to contact me if you have any additional questions or concerns.

Best Regards, Sean 480-829-8170 ext. 14

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