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An absolute beginner at this, so forgive me. Took an intro to EE class last year wherein we learned how to use op amps.

EE store had a bunch of free surplus LM348Ns and 741s that I collected for a potential rudimentary analogue computer project to test out electrical modelling of differential equations, integration, etc. However I had dropped one of them causing a couple of the DIP pins bend quite sharply, and in a haze of unhinged all-or-nothing OCD I tore the rest off down to the small exposed slits of metal where the legs once were, forgive me.

I then used my uni's tinker lab to attempt to solder some wires back on but the blobs of solder wouldn't adhere, probably because I had no flux, and I only ended up damaging the thing further, so I just sanded it down to see what was inside. A very tiny IC die, wow.

I know I got these mass-produced units for free and they're otherwise 60 cents apiece but it would just be nice to know how to repair IC legs for future reference, long before I ever dare to build a synthesizer from a Yamaha YM2151 chip.

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    \$\begingroup\$ What is your question? \$\endgroup\$
    – Voltage Spike
    Mar 3, 2023 at 6:01
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    \$\begingroup\$ @VoltageSpike, the question's there: "it would just be nice to know how to repair IC legs for future reference". \$\endgroup\$
    – TonyM
    Mar 3, 2023 at 7:40
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    \$\begingroup\$ Don't worry about it--741s are worthless anyway. \$\endgroup\$
    – Hearth
    Mar 3, 2023 at 13:39
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    \$\begingroup\$ It's better to just learn how to work in a way to not make mistakes worse and figure out tools and methods that work than to learn how to repair mistakes you yourself worsened. Then lesson here is to not tear off every pin when only some of them are bent, and to instead learn how to straighten bent pins, and if that fails and it break off, then how to solder a jumper to reconnect a missing pin (and use the remaining good pins for mechanical connection to the PCB). But learning how to repair an IC that has lost any means of mechanical support because you ripped all the pins is a waste of time \$\endgroup\$
    – DKNguyen
    Mar 5, 2023 at 23:55

4 Answers 4

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Pins tend to break off right at the edge of the IC package which leaves very little metal to solder a wire to. If not enough material is left on the outside of the package you can try to grind the package down to access the internal lead frame.

For DIP parts (and others) the lead frame makes up most of the package space and the chip is relatively small: enter image description here Image from the book "Open Circuits"

With the right grinding tools you might be able to access the remaining internal lead and solder a wire to it.

Here is a repair example of a broken pin, also applicable to similar DIP packages.

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    \$\begingroup\$ As long as the plastic molding case itself is not broken it is well possible to fix DIPs by grinding off the lead frame. Maybe not for space-tec and also not for mission-critical or live saving equipment. Be careful if the defective pins are in the middle of the IC as there is not much room for grinding without touching the bond wires. Lars' picture is a nice example of how most DIP chips look inside. \$\endgroup\$
    – datenheim
    Mar 3, 2023 at 14:09
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It’s possible but only something to try if there’s no other option. You’ll need to tin the remains of the pin and then solder a short length of tinned wire to it. Without fresh flux a blob of solder will start to oxidise very quickly if reheated, so if the surface isn’t bright and shiny then more flux is needed. Perhaps solder a relatively long wire and then cut it to length, as this will be easier to handle.

Back in the day a popular trick was to keep precious ICs in a dedicated socket and then insert that into another socket on the PCB - that was to avoid damaging the pins on your EPROM or whatever but could serve to protect a repaired pin.

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  • \$\begingroup\$ Good to know, looks like I got my work cut out for me in that case, and I've got a lot to learn. Thanks anyways! \$\endgroup\$
    – andrew g
    Mar 3, 2023 at 5:59
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it would just be nice to know how to repair IC legs for future reference

Generally if the pins are broken like that, there might also be breaks inside the die. The bonding could be damaged etc. Or it can seem to work fine then break later on because of strain introduced.

For this reason, during through-hole assembly, the technician is not allowed to bend the legs of a component at the point where it meets the component body. If the legs need to be bent to suit for example a 0.1'' grid, then they have to be bent further down the leg with flat nose pliers.

Summary: in a professional setting you don't repair an IC with damaged legs, you replace it.

As for DIP parts, the general best practice during prototyping/lab board assembly is to never solder them directly to the board, but to use DIP sockets.

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    \$\begingroup\$ Many commodity chips cost less than good quality sockets. Chip prices have gone up to the point that it might be worth using cheap sockets, but I've usually sought to avoid those. \$\endgroup\$
    – supercat
    Mar 3, 2023 at 23:55
  • \$\begingroup\$ @supercat - agreed, sockets offer little these days unless you know that you’ll need to remove/replace an IC, usually a direct connection is preferable \$\endgroup\$
    – Frog
    Mar 4, 2023 at 9:59
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    \$\begingroup\$ @Frog: On the other hand, I was surprised to observe that prices for many DIP chips have more than doubled in the last couple years, to the point that even commonplace chips like 74HCxx are now about the same price as sockets. \$\endgroup\$
    – supercat
    Mar 4, 2023 at 16:16
  • \$\begingroup\$ @supercat It's not so much the price as "oh damn I screwed up and now I have to order new parts". Whereas you can keep a stock of sockets around for the most common DIP sizes. \$\endgroup\$
    – Lundin
    Mar 6, 2023 at 7:28
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If you MUST repair an IC package as described then you already nailed it - flux. A good flux will allow you to perform miracles when it comes to soldering. Otherwise a new IC is always the answer. Using a slightly higher temp solder (e.g. Sn96) might help a little as it's stronger and will take a little more handling stress. I'd recommend OA flux for a cleaner result.

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