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desoldering IC chips that have thermal pad underneath

Discussion in 'General Electronics Discussion' started by danny davis, Jul 6, 2012.

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  1. danny davis

    danny davis

    306
    0
    May 9, 2012
    At work there is IC chips QFN that have a thermal pad underneath

    They have thermal vias holes on the other side of the PCB board

    How do u desolder these types of IC chips?
     
  2. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    Preheat from bellow... They have rework heater platforms just for this purpose...
     
  3. danny davis

    danny davis

    306
    0
    May 9, 2012
    do u have a link and what they are called?

    The bottom of the pcb has Via holes, how do u pre heat that?
     
  4. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    I said

    Remove the common words (they, have, just, for, this, purpose)

    And I know you are adamantly reluctant, to using GOOGLE buy if you type the remaining words into a GOOGLE search, wondrous things will appear right before your eyes...
     
  5. danny davis

    danny davis

    306
    0
    May 9, 2012
    sorry i don't have a thousand dollars and those preheats i have seen are so big

    I'm looking for a small one that is cheap

    Is this the only was to desolder the thermal pad?
     
  6. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    Too bad you gave up so easily, and didn't actually devote yourself or try to find one, you might have found the cheap small import ones that litter the Internet...

    See above...

    No, you can put the board in a reflow oven, or on a hot plate to put the chips as well... Or even do it with you heat gun if you devote yourself to the task at hand...
     
  7. danny davis

    danny davis

    306
    0
    May 9, 2012
    I have tried that and it melted the IC chip really fast
    the IC chip melts fast

    What is the LINKS you're looking at? brand names please?

    They are called preheaters? or rework preheaters?
     
  8. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    As I keep telling you operator error and improper technique, you have to actually devote yourself and learn a technique... 99% of your problems are due to your lack of experience, you need to educate yourself with more hands on practice and MUCH less blaming the tool...

    I'm not looking, you are... I have simply provided you direction and I can't help those that refuse to help themselves, and I see absolutely no reason why I should do a GOOGLE search and provide you with direct links because you are too lazy to do it yourself...

    Heck I suspect even if I did direct link you rather then saying 'thanks' it would only be met with some other complaint, reason why it won't work, you can't afford that or some other excuse, as has been your modi operandi in other threads...
     
  9. danny davis

    danny davis

    306
    0
    May 9, 2012
    ok bye
     
  10. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    What do you have against doing your own Google searches? I point you in the right direction and 7 minutes later you have already given up and come back asking for a direct link complaining that you can't afford some $1000 system and that they are too big... Did you even really try? How many systems did you look at? Or did you just give up after a minute or two when it wasn't handed to you on the first page you stumbled upon? How many websites did you look at in that 7 minute time frame between my post and yours? How many different types heaters did you look at?

    There are small preheaters out there about the size of a paperback book for under $100, all it takes is a little work on your end to find them... That would be both small and low cost, just what you imply you desire...
     
  11. danny davis

    danny davis

    306
    0
    May 9, 2012
    The preheaters i seen look like they will preheat multiple components at the same time

    I just want ONE chip that is very SMALL

    Plus the preheaters , heats up the bottom of the PCB board

    If you preheat the TOP of the PCB board it will preheat multiple components at the same time

    I DON"T WANT THIS
     
  12. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    No, they preheat an area of the board, to facilitate rework in this case...

    Yeah, I'm aware of that... But, that doesn't really factor in as the preheaters job is to simply temper the board to make it easier to rework in this case...

    Exactly, that leaves you able to rework the top of the board and your single chip just like you want...

    You don't heat the top of the board, you heat the bottom and then rework the top in this instance...

    Actually yes this is exactly the information you proclaim you wanted... But as usual you don't like the answer and thus complain and argue... You asked "desoldering IC chips that have thermal pad underneath" and that is exactly what I was attempting to help you with, but instead of listening, you instead want to argue as if you already know how to do it... The preheater will in fact facilitate the ability to rework a chip with a thermal pad under the chip or a BGA... It's clear you simply just don't understand how to use it and what it facilitates, and you have no interest in actually listening to someone that knows exactly how to do it and has done it more times then I care to remember counting...

    And remember when I said this a few post back, it's like I can see the future...

    That isn't a big $1000 unit as you proclaimed previously....

    That's a guitar, what does it have to do with anything?

    Again, I'm not seeing this big $1000 unit you so strongly protested about...

    Those both look like small compact preheaters that will help you a great deal in working with the removal of a chip with a hidden thermal pad...
     
    Last edited: Jul 6, 2012
  13. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    Danny may I suggest you take 5 minutes of your time and educate yourself on how a preheater works in this application before you reply again, OK? It's clear you don't have a clue on how to go about doing what you want, and how a preheater as I have suggested will enable you to do it, but instead just want to argue about something you know little about...

    Watch this video of a guy removing a BGA chip, THE SAME EXACT TECHNIQUE AND PRINCIPLES APPLY TO REMOVING A QFN CHIP WITH A HIDDEN THERMAL PAD using a preheater!!! This is EXACTLY what you asked how to do...

     
  14. danny davis

    danny davis

    306
    0
    May 9, 2012
    is there any other way to do this beside using a preheater rework station?

    Can I use a coffee cup heater? or use a Hot air gun to heat up the Thermal VIAS holes?
     
  15. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    There are always alternative ways to do things... Your mileage will vary using any method based on your abilities to execute that technique... Based on your previous post and your lack of soldering skills, I would highly suggest you focus doing it properly with the proper tools or you will be destroying board after board...

    In a professional work environment I wouldn't hesitate to invest the $100 and do it right, it will save you a lot of grief and aggravation in the end... Yes, there are other ways to do it and yes I have done it without a preheater, but I also consider myself highly skilled in soldering and rework thus making alternative techniques much easier to implement... The $100 a preheater cost will pay for itself in no time, you will easily waste hours upon hours of labor tying to fiddle with other techniques when it could have been done in a minute or two with the proper tools...

    Preheaters are the way this type of rework is done pretty much across the board in any professional shop, it's the proper tool for the job...
     
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