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Max temperature exposure for surface mount devices?


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#1 Suicide King

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Posted 23 March 2011 - 08:27 PM

Does anyone know what the maximum temperature exposure for surface mounted chips is when soldering them onto (or off of) a motherboard? I've read you don't want to exceed much more than 250C for only a few seconds. I was thinking around 230C or so for 15 seconds, maybe 20. Some of the potential items to surface mount are a GPU, CPU, Northbridge, and Southbridge on a particular device.

Anyone with experience attaching surface mount devices, who could give some guidance, would be appreciated. Thanks for the help!

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#2 Sneakycyber

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Posted 31 March 2011 - 12:57 AM

I have installed smd led's before and I used a butane soldering iron that's about the closest I got to a graphics chip. The chip manufacture should have specs on it.
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#3 Suicide King

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Posted 31 March 2011 - 08:07 AM

I have installed smd led's before and I used a butane soldering iron that's about the closest I got to a graphics chip. The chip manufacture should have specs on it.


Any idea where I could find some of these specs? I wasn't able to find anything about max temps for surface mounting -- only max operational temperatures.

#4 Baltboy

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Posted 31 March 2011 - 08:42 AM

The max operating temp and soldering temp should be close to the same thing. Slightly hotter during soldering is usually acceptable since it is shorr term. If it is a low temp use an easy flow low temp solder and allow it to cool between joints.
Get your facts first, then you can distort them as you please.
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#5 Suicide King

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Posted 31 March 2011 - 09:30 AM

I've been looking for a good centralized place to find information on operating temperatures for a variety of CPUs. They seem scattered over the manufacturer's documents. Anyone know some good spots?

Furthermore, a lot of processors max out at around 70-80c. Those temps would not quite be hot enough for lead based solder, which normally melts around 230-250F (110c - 121.11c). You think there might be some sort of separate standard for surface mounting temps vs operating temps?

Edited by Suicide King, 31 March 2011 - 09:36 AM.


#6 Sneakycyber

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Posted 02 April 2011 - 12:27 AM

The operating temp reflects some heat dissipation the actual internal on die temp of the component could be much higher. Generally for power dissipation you over compensate by a factor of 2 this helps components last longer. As for a repository of CPU temps I haven't found one although I haven't looked in awhile either
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#7 Sneakycyber

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Posted 02 April 2011 - 12:29 AM

Found this http://www.pantherproducts.co.uk/Articles/CPU/CPU%20Temperatures.shtml
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#8 Suicide King

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Posted 02 April 2011 - 08:32 AM

The operating temp reflects some heat dissipation the actual internal on die temp of the component could be much higher. Generally for power dissipation you over compensate by a factor of 2 this helps components last longer. As for a repository of CPU temps I haven't found one although I haven't looked in awhile either


So what you're saying is that the maximum temperature exposure for a CPU with a max operating temperature of 80c would be 160c? Seeing as you're compensating by 2x. So an exposure of 110-122c should be well within that compensation, especially for a period of only 10-40 seconds... Sound reasonable?

Thanks for the help, by the way. I appreciate the information.

#9 Sneakycyber

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Posted 02 April 2011 - 09:52 AM

In theory yes although I would never run a processor past the manufactures temperature threshold you have a very good chance of flashing it you never know where they scrimp on tolerances. I can verify my thoughts with my Electronics professor next week it just so happens we are covering soldering in my DC analysis class.
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#10 Suicide King

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Posted 02 April 2011 - 03:33 PM

Actually I'm a bit off as far as my temps. The melting point of common electronics solder is 179c. It's pushing that double limit.

I wasn't planning on running the processor past the manufacturer's temps -- only heat it beyond those temps for a limited time.

If you could check with your professor that'd be a help. It's hard to find documentation about this.

#11 Sneakycyber

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Posted 14 April 2011 - 06:55 AM

I just talked with my professor and he said the thermal limits should be given on the data sheet for the component. If its not then its a guessing game. they had to get it soldered on there somehow though. I would venture to guess the lowest temperature you can use to melt the solder would be best. I would think you would be safe that way. Off the top of my head there is no "special" way they mount SMD devices.
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