[synaesthetic]

Okay so this evening I spent a few hours assembling my Sijosae diamond buffers for my PIMETA. I've noticed this in the past, but when soldering IC components, they tend to get rather hot. I went fairly slowly the whole time, since the buffers are on tiny pieces of perfboard 4 pins wide by 5 pins long, and I knew that if I made a mistake I'd be unable to salvage any of my work.

In any case I only botched one buffer, but was able to make three to complete the set easily enough. The whole exercise was a lesson in creative lead-bending.

None of the TO-92 parts got hot enough to burn me, but I couldn't leave my finger on them for any longer than ten seconds or so. I'm fairly sure none of them are damaged but I am curious as to how hot these things can get before bad stuff happens?

 

[FallenAngel]

For the general answer, check the datasheet. You can get them fairly hot (>300C) for short periods of time and you'll do no damage. You just can't run them at those temps for too long. Most ICs will either thermal shutdown or fry above 70C. General rule is if you can keep your finger on it for a few seconds, you can run it at that temp indefinitely.

 

[TzeYang]

what kind of temperature are you working with?

Personally, you should work with 300 Celcius (if yours is adjustable) or at most 25watt soldering iron. This way you get more control and won't overheat the leads easily.

Anyway, personally, try to solder one lead at a time. let it cool down before soldering another one. It's a safest way possible if you're afraid you might screw it up.

 

[synaesthetic]

I am using a 25W iron, and none of the TO-92 parts got hot enough to where it hurt enough that I had to remove my finger from them after the soldering.

 

[nikongod]

Quote:

Originally Posted by synaesthetic /img/forum/go_quote.gif I am using a 25W iron

if you plan on doing more of this, get a better iron. a 40-60W temperature controlled iron is your new best friend. it makes delicate work like this much easier.
Quote:

and none of the TO-92 parts got hot enough to where it hurt enough that I had to remove my finger from them after the soldering.

If your finger was on them the whole time, and never got burnt you are good to go. Skin burns at like 105*f, most transistors can handle a few seconds WAY beyond that temperature.

 

[xmokshax]

Quote:

Originally Posted by nikongod /img/forum/go_quote.gif if you plan on doing more of this, get a better iron. a 40-60W temperature controlled iron is your new best friend. it makes delicate work like this much easier. If your finger was on them the whole time, and never got burnt you are good to go. Skin burns at like 105*f, most transistors can handle a few seconds WAY beyond that temperature.

i agree wholeheartedly with the temperature-controlled iron recommendation - it'll make a wide range of soldering jobs a lot easier.

however, i think your estimate that skin burns at 105F is a touch low... if that were the case, you'd have had burns to your entire body after a trip to the hot tub that's just SLIGHTLY hotter than than normal. i think a reasonable estimate is that skin burns around 65-70C (in the neighborhood of 150F). in any case, not terribly important... just for the record

 

[synaesthetic]

Skin burns starting around 140-150 F increasing in severity from there. Seven years as a restaurant cook, I should know. =P The steamwells were kept at that temperature and you could definitely burn yourself on any of the food kept in them.

And I do intend to buy a better soldering iron, but for now I'm using this low-end Weller 25W iron I picked up from Lowe's until I can find a good variable station that will do everything I need it to do.

My biggest problem with the Sijosae buffer was, on the first one, the one I botched, I tried to solder TOO many things. After looking at the schematic and a photo of the finished product, I discovered that I only NEEDED to solder where the leads of the components actually joined together. The whole thing was a lot of fun, really, working from just a schematic and a photo, but I'm not too keen on working on such a tiny board in the future. =p

 

[SiBurning]

It might help if you mount a heatsink to the part before soldering. Another trick is to use a clamp-on scissor looking heatsink thing (what's it called?) on the lead between the solder point and the part, but this also sucks heat away from the joint. Then wait between soldering each joint to let the parts cool off.

There's heatsinks for ICs. Or... this is a good use for a socket so you don't ever risk the part.

 

[ericj]

A hotter iron and good flux make it possible to heat the lead for a shorter amount of time for the same or better solder joint, and pump fewer BTUs into the part than you would with a cooler iron and no flux. Yeah even considering that you have rosin-core solder.

 

[synaesthetic]

The iron I'm using isn't especially hot, but it is sufficient. I won't be soldering any opamps directly (all going through sockets) so I'm less worried about that, and I wasn't even really too worried about the TO-92 parts because they're cheap.

Frying rail splitters IS kind of a pain though because they're not so cheap and ordering them online is about the only way to get them. But that is a fairly easy part to solder. The buffers were a pain because the perfboard pieces were so small and difficult to hold still.