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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Doug Batten

#10986

BGA Heat Sinks | 17 June, 1999

Does anyone have experience with placing heat sinks on BGAs? I have limited experience with PSA (pressure sensitive adhesives)heat sinks, and am interested with the possibility of a clip-on device. I am specifically concerned with ease of assembly (either manual or automated), reliability (heat sink doesn't fall off with time/temp), cost, and thermal transfer performance.

Thanks in advance, Doug

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Earl Moon

#10987

Re: BGA Heat Sinks | 17 June, 1999

| Does anyone have experience with placing heat sinks on BGAs? I have limited experience with PSA (pressure sensitive adhesives)heat sinks, and am interested with the possibility of a clip-on device. I am specifically concerned with ease of assembly (either manual or automated), reliability (heat sink doesn't fall off with time/temp), cost, and thermal transfer performance. | | Thanks in advance, Doug | The others can give you names. I'll give you trouble. Only kidding.

We use both types. One must be very careful when using adhesives as too much defeats thermal transfer effectiveness. The stuff is only supposed to "smooth" out the rough areas as scratches, dents, and other surface irregularities so an intimate contact, as well as high thermal transfer, is assured.

Rework can be an issue with thermal adhesives as you cannot pull a BGA with its heat sink attached though I doubt, in your perfect process, you'll ever encounter such difficulties. This is where clip on's have an advantage. However, they must be securely attached to ensure, as your concern states, they don't come off.

Earl Moon

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JohnW

#10988

Re: BGA Heat Sinks Adhesive Alternative | 21 June, 1999

| | Does anyone have experience with placing heat sinks on BGAs? I have limited experience with PSA (pressure sensitive adhesives)heat sinks, and am interested with the possibility of a clip-on device. I am specifically concerned with ease of assembly (either manual or automated), reliability (heat sink doesn't fall off with time/temp), cost, and thermal transfer performance. | | | | Thanks in advance, Doug | | | The others can give you names. I'll give you trouble. Only kidding. | | We use both types. One must be very careful when using adhesives as too much defeats thermal transfer effectiveness. The stuff is only supposed to "smooth" out the rough areas as scratches, dents, and other surface irregularities so an intimate contact, as well as high thermal transfer, is assured. | | Rework can be an issue with thermal adhesives as you cannot pull a BGA with its heat sink attached though I doubt, in your perfect process, you'll ever encounter such difficulties. This is where clip on's have an advantage. However, they must be securely attached to ensure, as your concern states, they don't come off. | | Earl Moon

| Doug / Earl

have either of you heard of an adhesive tape for sticking heat sink's on. There's this company I found on the net ( won't name it but if your interested drop me a note and I'll forward the info). They produce thermal trasfer adhesives for heatsink's but they also do this doublesided sticky tape for the want of a better description. It's got all the properties you want for herat trasnfer and stability but it comes as pad's that are cut to size, sure you may have to pay a small charge to the cutting tool but I recon you'll save a tonne of cash on rework, it's easily removeable without using any nasty chemicals or heat processes. The application is like using a 2 second job. I used it on 1 contract and saved a whack of time and money on assembly, and when ( on the rare occation) 1 fell out of soak or functional test i could rework it and push it back through ATE minus since I could peel the heatsink off. Was one of those thing's when you think..hey this would be great..I should copyright this..then you find out you've been beeten to it..gee now how do I make my millions...???( answer's on a postcard to John@smtnet....)

JohnW

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John Thorup

#10989

Re: BGA Heat Sinks Adhesive Alternative | 21 June, 1999

| | | Does anyone have experience with placing heat sinks on BGAs? I have limited experience with PSA (pressure sensitive adhesives)heat sinks, and am interested with the possibility of a clip-on device. I am specifically concerned with ease of assembly (either manual or automated), reliability (heat sink doesn't fall off with time/temp), cost, and thermal transfer performance. | | | | | | Thanks in advance, Doug | | | | | The others can give you names. I'll give you trouble. Only kidding. | | | | We use both types. One must be very careful when using adhesives as too much defeats thermal transfer effectiveness. The stuff is only supposed to "smooth" out the rough areas as scratches, dents, and other surface irregularities so an intimate contact, as well as high thermal transfer, is assured. | | | | Rework can be an issue with thermal adhesives as you cannot pull a BGA with its heat sink attached though I doubt, in your perfect process, you'll ever encounter such difficulties. This is where clip on's have an advantage. However, they must be securely attached to ensure, as your concern states, they don't come off. | | | | Earl Moon | | | Doug / Earl | | have either of you heard of an adhesive tape for sticking heat sink's on. There's this company I found on the net ( won't name it but if your interested drop me a note and I'll forward the info). They produce thermal trasfer adhesives for heatsink's but they also do this doublesided sticky tape for the want of a better description. It's got all the properties you want for herat trasnfer and stability but it comes as pad's that are cut to size, sure you may have to pay a small charge to the cutting tool but I recon you'll save a tonne of cash on rework, it's easily removeable without using any nasty chemicals or heat processes. The application is like using a 2 second job. | I used it on 1 contract and saved a whack of time and money on assembly, and when ( on the rare occation) 1 fell out of soak or functional test i could rework it and push it back through ATE minus since I could peel the heatsink off. | Was one of those thing's when you think..hey this would be great..I should copyright this..then you find out you've been beeten to it..gee now how do I make my millions...???( answer's on a postcard to John@smtnet....) | | JohnW Loctite makes a removable thermally conductive adhesive as #384. We use the permanent version (383) for QFP sinks and it works nicely. Doug, you didn't say if your PGA had a flat top or not. If it's a glob top PBGA, tape or clip aren't going to do much good. I'm not a real fan of metal clips. I've had a few pop off with disastrous results. John Thorup

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Chris

#10990

Re: BGA Heat Sinks | 24 June, 1999

| Does anyone have experience with placing heat sinks on BGAs? I have limited experience with PSA (pressure sensitive adhesives)heat sinks, and am interested with the possibility of a clip-on device. I am specifically concerned with ease of assembly (either manual or automated), reliability (heat sink doesn't fall off with time/temp), cost, and thermal transfer performance. | | Thanks in advance, Doug | You should also look at thermoset/Lord. they have released a product called "gelease" that is getting go results for thermal transfer and the have a tape version also.

Regards Chris

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