Desoldering IC chips, use hot air gun or 85 watt soldering iron?

Discussion in 'General Electronics Chat' started by Calton57, May 5, 2015.

  1. Calton57

    Thread Starter Member

    May 4, 2015
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    Is there a way to desolder through hole double side board dual in line IC chips that are 14pins to 16 pins using a hot air gun?

    I'm trying to find a way so the Dual in line IC chips just Slide out like butter. Maybe using a preheater on the board of the board and using a hot air gun on the top of the board to slip out the dual in line Ic chips.

    I read in electronic books that it's bad to desolder dual in line chips and reuse them because of multiple heating cycles which damage the chips and if you reuse the IC chip it causes latency failures. When apply a soldering Iron tip to the IC pins it damages the internal components?

    Also is there a difference between using a 45 watt solder iron setting at 600 degrees 65 watt soldering iron at setting 600 degree compared to using an 85 watt soldering iron setting set at 600 degree. They are all set at the same temperature degrees but the higher the wattage melts double sided through hole IC chips better?

    To desolder through hole dual inline IC chips is it best to use a 100 watt soldering iron to it melts both sides easier? Plus the higher the wattage is better for no lead solder.
     
    Last edited: May 5, 2015
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    The higher wattages re-establish their temp much faster after contacting a cold surface.

    I have good luck melting some regular (tin/lead) solder to the contacts on Pb-free boards then gently lifting the board by the component (with channel-loc pliers) and hitting it with a hot air gun that has been pre-heated.

    The faster you can heat the board, the less damage is likely (like cooling a steak, "the higher the heat, the rarer the meat").

    Good luck and don't get burned.
     
  3. kubeek

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    Last edited: May 5, 2015
  4. dl324

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    Mar 30, 2015
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    Not the best tool for the job. Getting the solder on all of the pins molten is going to fry the part and possibly the board.
    If you had a heated tool like a IC inserter, you could do it; but you'd still have to clear the solder from the board if you were doing a repair.
    That book is wrong. If you have proper technique, you can remove parts without damaging them. The key is knowing what you're doing and having proper technique.
    Higher wattage will melt the solder faster. When working on ground planes, more wattage is mandatory.
    You're confusing the higher melting point for lead free solder with wattage.
     
  5. Calton57

    Thread Starter Member

    May 4, 2015
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    So what wattage do i use for lead free solder?

    I have read many times for different electronic books that when apply a soldering iron on transistors and IC chips that the heat damages the semiconductors

    DL324 said:
    Yes do they make something like this?

    Is there anything I can use to test Dual In line IC chips in circuit? I hate taking them out of circuit to put them in a universal programmer to test the IC chips.

    Which universal programmers do you know that test IC TLL, CMOS and analog Op amps? There is universal programmers that test ROM chips , RAM chips, EEPROM chips as well as TTL, CMOS , OP AMPs
     
  6. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    600 Kelvin is a perfectly acceptable temp for soldering. Why do you deal in Celcius. I thought you were a scientist or engineer!
     
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  7. Calton57

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    May 4, 2015
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    Sometimes I lift the soldering pads, Do you know what type of glue or epoxy to use to put the pads back on the PCB board?
     
  8. dl324

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    Googled and found this http://www.drviragopete.com/ic-desoldering.php It isn't what I was looking for, I remember seeing something with more thermal mass when I was a tech; but this is similar in principle. You heat all leads at the same time. The tool I had in mind allowed you to put pressure on the pins so you could lift from the board. Picture below.
    You can use something like an HP10529A Logic Comparator. Works for 14-16 pin dips, TTL for sure, CMOS maybe.
    I don't. I troubleshoot the old fashioned way; in circuit and running at speed. I have an HP10529A, but have never used it.
     
  9. dl324

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    If you're lifting pads, you're applying too much heat.

    Repair isn't fun. http://www.circuitmedic.com/
     
  10. dl324

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    Here's what looks to be a better version of the removal tool.
     
  11. Calton57

    Thread Starter Member

    May 4, 2015
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    dl324
    If i can't power up the circuit board, do you know what i can use?

    I have been using a huntron tracker 2000 to compare a reference IC chip with the suspected IC chip in circuit.

    Is there a way to use a external reference IC chip out of circuit that has the same part number but put it in parallel like how the HP Logic comparator does but using the power turned off. It won't be using the HP logic comparator but something that I can put the reference IC chip that is out of circuit in parallel with the suspect IC chip. I would need some type of circuit that has buffers so i can put a reference IC chip out of circuit to compare with the IC chip that is in circuit so I can compare the huntron signatures to each other.

    The Huntron tracker 2000 and 2500 can only be used when the circuit board under test has it's power turned OFF. That is why i need something like a HP 10529 but worked when the power is turned off.
     
  12. Calton57

    Thread Starter Member

    May 4, 2015
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    Who makes those dip removal tools? I remember seeing PACE & Metcal making them but PACE & Metcal went out of business a long time of ago
     
  13. Calton57

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    May 4, 2015
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    Here is a couple IC desoldering tips made by weller

    IC desoldering tips DiL 24, type Weller T005417
    IC desoldering tips DiL 16, type Weller T005417
     
  14. dl324

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    Figure out what's causing it to not power up. Then go from there.
    I don't see how that can work. You have to apply power to the chip to test it and that would power up the rest of the board. Even if you removed the power pins from the device you're testing, any wiggling could connect power to the board.

    I don't have much use for in-circuit testing. I don't see how it can give good results. Many times, you can't even measure the resistance of a resistor; too many things interconnected.
     
  15. Calton57

    Thread Starter Member

    May 4, 2015
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    dl324
    Most companys know of days don't supply the schematics to the circuit boards and don't want you to power up the boards. So to troubleshoot the circuit boards they want you to use a huntron tracker. The reference IC chip is the same part number but its out of circuit and the IC chip is in circuit so i get totally different results. Is there a way i can put the reference IC chip in parallel with the IC chip that i'm trying to test in circuit so i can compare the good reference IC chip that would be "bridged" in circuit?

    I have a total of 30 different IC chips on each board and i can't power them up or have schematics. So how can I verify that the IC chips work or not?

    The only other way is to use a IC desoldering Tip and desolder each IC chip one by one out of circuit and use a special universal programmer that tested TTL, CMOS , Op amps, RAM chips, ROM chips, EEPROM chips
     
  16. alfacliff

    Well-Known Member

    Dec 13, 2013
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    I usede to change chips in bad boards in bars in the dark. back in my video games and pinball days. I used a weller 120 watt temprature controlled gun and a "soldapulit" solder sucker. with a bit of practice,we you can do it with that and not lift pads. lifting pads is due to excess heat or time. get some old boards to practice on till you get your method to work properly. when solder is left, or a broken pin in a hole, use a stainless dental pick, the kind that looks like a needle with a handle to poke through the hole when the solder is melted, solder will not stick to stainless, and wll leave the hole open. a low power iron will take longer to melt the solder and risk lifting pads. on double sided boards, use a bit of stripped wire wrap wire fed through the hole to join the runs on top and bottom.
     
  17. dl324

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    Seems that they want you to send it to them for repair or buy a replacement... If it's your board, you can do what you want.
    This just seems like an excuse to not study the logic on the board and make educated guesses as to what might be causing the problem. I've never felt like I needed an easy way out. I just kept digging deeper until I found the problem. I remember spending days tracking down a single (though difficult) problem. But that was why I became a tech.
    Skill and persistence.
    Back in the day, we called this method "shot gun". You just picked a bunch of chips to replace and hope that it fixed the problem. I never thought much of that technique; or the people who used it...
     
  18. alfacliff

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    Dec 13, 2013
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    I ha\ve never used a huntron tracker. I also haver seldom had any diagrams for boards, yet, I have been sucessfull at board level repair for a lot of years. I have worked on lots of different thngs, from digital radar for RCA (with diagrams and training), computers for NCR ( with diagrams and training) car stereos ( sometimes diagrams), cb's ( sometimes diagrams) video games, juke boxes and pinballs ( sometimes diagrams) as well as various ham reicevedrs, transmitters,and trancievers for about 50 years now. I woked on a lot of sutff in the army, mostly with training, however as the only tech with transmitter experience at my post in Turkey, I got to work on some transmitters nobody would touch. as you get better and more experience, youwill find it easier to get along without all the diagrams and literature,.
     
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  19. dl324

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    Kudos to you! There is no substitute for knowledge, technique, and persistence.
     
  20. BR-549

    Well-Known Member

    Sep 22, 2013
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    Calton57,

    I use to repair many boards without knowing anything about them.

    They now call the device you need, an octopus.

    When I was using it, it was called a component tester.

    This device works with an oscilloscope in x-y mode.

    The board being repaired is never powered up.

    A small ac voltage is put across the scope probes.

    With a little practice, you can check every component and gate, junction on the board.

    A quick way to make good money.

    I use to repair any dog with this.
     
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