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I generally like to solder sockets to my boards, rather than the chip directly, but am now forced to solder the chips directly. I have several DIP and SMD components that this needs to be done with.

I am concerned that the heat from soldering them might damage the chips so was wondering how I could heat sink them? Is this even necessary?

It doesn't apply to me right now, but how is this done with other packages?

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    \$\begingroup\$ Solder faster... Seriously. \$\endgroup\$ – Connor Wolf Aug 1 '10 at 8:18
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I have used these tips to get started with SMD soldering. Until now I have not found it necessary to drain heat as long as you mind where you put the soldering iron tip and don't apply heat any longer than needed.

http://www.infidigm.net/articles/solder/ - The second article is better, see comments

PS: This article may help as well, it seems to be quite good:

http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=36&page=1

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    \$\begingroup\$ Wow those articles actually do help... I'd never tried applying solder to the board, THEN the chip. Explains why my SMD stuff never works :-P \$\endgroup\$ – samoz Jul 1 '10 at 13:53
  • \$\begingroup\$ I found the sparkfun one after answering your question, have actually been studying the little youtube videos they did to learn a few more techniques. I burnt my fingers, but it works though! :D \$\endgroup\$ – Wouter Simons Jul 1 '10 at 13:57
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    \$\begingroup\$ first guide is fine as far as how you physically go about it but the "flood and suck" method, well, sucks. just use some flux and you don't need to suck at all. In fact the major point missing in that article is that flux is your friend. Get some no-clean flux pens and you can solder pretty much anything with exposed pads very quickly with almost any sized tip. \$\endgroup\$ – Mark Jul 31 '10 at 23:02
  • \$\begingroup\$ I agree in hindsight that the flood and suck method is not the best way to go, have been experimenting with the solder wick approach explained in the second article and it works much better. Try that instead I would say. \$\endgroup\$ – Wouter Simons Sep 1 '10 at 6:56
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Your worries are unjustified. The graph shows a typical temperature profile for reflow soldering.

enter image description here

Note that all of the IC is subjected to temperatures close to and above 200°C for minutes. Not one pin, all of them, and the IC's body as well. No pin-by-pin soldering can apply that much heat to the package.

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You can buy a tool that is a heatsink designed for temporary use while soldering. They look like clumsy pliers. That will work well for the DIP components.

For SMD components, you might try putting something cold with large thermal mass and high thermal conductivity (say a chunk of aluminum foil you put in the freezer for a while). I've held stuff like that in place with a rubber band around the PCB, and it makes some difference.

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Most datasheets will list what the max soldering temperature is for the chip, you should look these up and make sure you don't exceed them.

For surface mount chips, a reflow profile is usually also included in the datasheet. These profiles show a time versus temperature graph to use when soldering using ovens. Even if you aren't using an oven, it is still good to look at for an idea of how much temperature for how long should be applied.

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I solder up tons of SMD boards by hand, and I have to say that I don't think I've ever seen a chip damaged by solder heat. This may have been a problem back in the old days, but new chips are made to survive lead-free reflow soldering temperatures.

But here's a good tip. Hold your finger on the chip while you solder it. Firstly, this helps to drain heat from it. Secondly, if it gets too hot for your finger, stop soldering for a bit.

Hugo

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  • \$\begingroup\$ Two points - heat sensitivity is largely dependent on the type of part. SMD LEDs in particular should not be heated up too much. I'd agree that the parts which traditionally go in sockets won't be damaged. I disagree that the finger method is a good idea because your finger will get burned, and 'too hot for your finger' is much, much less than too hot for most any chip. \$\endgroup\$ – Kevin Vermeer Jul 31 '10 at 20:31
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    \$\begingroup\$ meh you build up a resistance after you burn your finger a few times and have a nice build up of excess skin. \$\endgroup\$ – Mark Jul 31 '10 at 23:03
  • \$\begingroup\$ Kevin is right: too hot for your finger is hardly tepid for an IC. Rule-of-thumb for too hot to touch: 60°C. And your finger won't drain much heat away (even if you can stand it). Bad thermal conductor. \$\endgroup\$ – stevenvh Jul 28 '11 at 15:45

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