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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Charles Stringer

#11350

Heatsinks for surface mount devices | 24 May, 1999

Can anyone steer me towards a supplier of heatsinks suitable for use on a PQFP 160. Before you shoot me down in flames, I know that I am not going to get much heat away from the die because of the plastic but the application is such that the board temperature is high and ambient is lower so any heat conduction away from the micro will help. Usual rules, minimal cost, no assembly issues, readily available....

reply »

john thorup

#11351

Re: Heatsinks for surface mount devices | 24 May, 1999

| Can anyone steer me towards a supplier of heatsinks suitable for use on a PQFP 160. Before you shoot me down in flames, I know that I am not going to get much heat away from the die because of the plastic but the application is such that the board temperature is high and ambient is lower so any heat conduction away from the micro will help. | Usual rules, minimal cost, no assembly issues, readily available.... Any number stock heat sinks would be available from the usual suspects. Try one made for a TO-220 device. We use this solution on a PQFP 80 DSP chip that was uncomfortably hot before sinking. Measurements and calculations showed that it worked better than you would expect. We use Loctite 383 thermally conductive adhesive to attach the sink. We haven't had one come off yet.|

reply »

JohnW

#11352

Re: Heatsinks for surface mount devices - adhesive alternative! | 24 May, 1999

| | Can anyone steer me towards a supplier of heatsinks suitable for use on a PQFP 160. Before you shoot me down in flames, I know that I am not going to get much heat away from the die because of the plastic but the application is such that the board temperature is high and ambient is lower so any heat conduction away from the micro will help. | | Usual rules, minimal cost, no assembly issues, readily available.... | Any number stock heat sinks would be available from the usual suspects. Try one made for a TO-220 device. We use this solution on a PQFP 80 DSP chip that was uncomfortably hot before sinking. Measurements and calculations showed that it worked better than you would expect. We use Loctite 383 thermally conductive adhesive to attach the sink. We haven't had one come off yet.| | | Charles,

Dont know if this is any help but I looked at an alternative to using the loctite adhesive. The main reason is that if you apply the heatsink after ICt and have to go back and test it..getting the heat sink off is a dam hard thing to do. I found a conductive pad by a company called Wrath International. You can have it cut to custome sizes if you need to but I think a QFP160 is available. The assembly time is practically zero, the adhesion is great and you can rip it off easy enough if you need to rework the board after. I've got the address at work so if you cant find it on the net give me a shout.

JohnW

reply »

John Thorup

#11353

Re: Heatsinks for surface mount devices - adhesive alternative! | 25 May, 1999

| | | Can anyone steer me towards a supplier of heatsinks suitable for use on a PQFP 160. Before you shoot me down in flames, I know that I am not going to get much heat away from the die because of the plastic but the application is such that the board temperature is high and ambient is lower so any heat conduction away from the micro will help. | | | Usual rules, minimal cost, no assembly issues, readily available.... | | Any number stock heat sinks would be available from the usual suspects. Try one made for a TO-220 device. We use this solution on a PQFP 80 DSP chip that was uncomfortably hot before sinking. Measurements and calculations showed that it worked better than you would expect. We use Loctite 383 thermally conductive adhesive to attach the sink. We haven't had one come off yet.| | | | | Charles, | | Dont know if this is any help but I looked at an alternative to using the loctite adhesive. The main reason is that if you apply the heatsink after ICt and have to go back and test it..getting the heat sink off is a dam hard thing to do. | I found a conductive pad by a company called Wrath International. You can have it cut to custome sizes if you need to but I think a QFP160 is available. The assembly time is practically zero, the adhesion is great and you can rip it off easy enough if you need to rework the board after. | I've got the address at work so if you cant find it on the net give me a shout. | | JohnW | | John W is entirely correct about the testability/rework issue. In our application the entire heatsink fits into our APE rework station so it is not an issue. Loctite also has their 384 thermally conductive adhesive which is described as removable. Pressure sensitive phase change material on a foil substrate is available from Orcus. It works well but there is a rather large minimum order. McMaster-Carr has smaller quantities of what appears to be an acceptable tape as as their stock #77095A4. I have not tried it.

reply »

SP700avi inline stencil printer

ii-feed SMD Intelligent Feeder