Best Method to Align Small IC while replacing

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  • IamPritesh
    Badcaps Veteran
    • Aug 2017
    • 354
    • India

    #1

    Best Method to Align Small IC while replacing

    It usually takes a lot of time to place a new chip perfectly. For example (charging ic or 3/5V IC ). I understand lots of practice is required but I was wondering what is the best method you use .Which hand do you use to hold the heat air blower and so on.


    Thanks
    Last edited by IamPritesh; 10-31-2019, 09:58 PM.
  • mcplslg123
    Badcaps Legend
    • Jun 2015
    • 7262
    • india

    #2
    Re: Best Method to Align Small IC while replacing

    It depends on practice as you have already said. Its important to use good quality flux so that the ic gets it to place when heated even though not aligned very perfectly.

    Comment

    • IamPritesh
      Badcaps Veteran
      • Aug 2017
      • 354
      • India

      #3
      Re: Best Method to Align Small IC while replacing

      Originally posted by mcplslg123
      It depends on practice as you have already said. Its important to use good quality flux so that the ic gets it to place when heated even though not aligned very perfectly.
      Which flux do you use ? Do you grip the IC with the help of a Tweezer while you apply heat ?

      Comment

      • anshad
        Badcaps Veteran
        • Nov 2010
        • 249

        #4
        Re: Best Method to Align Small IC while replacing

        Originally posted by IamPritesh
        It usually takes a lot of time to place a new chip perfectly. For example (charging ic or 3/5V IC ). I understand lots of practice is required but I was wondering what is the best method you use .Which hand do you use to hold the heat air blower and so on.


        Thanks
        Which hands to use depends on what you feel comfortable. Try yourself using both hands and which one you feel unshaken and steady while doing the job, stick to that one. Refer the below video, its the way most of the professionals solder QFN chips

        https://www.youtube.com/watch?v=c_Qt5CtUlqY

        Comment

        • mcplslg123
          Badcaps Legend
          • Jun 2015
          • 7262
          • india

          #5
          Re: Best Method to Align Small IC while replacing

          Originally posted by IamPritesh
          Which flux do you use ? Do you grip the IC with the help of a Tweezer while you apply heat ?
          I use AMTECH flux. No i dont grip the ic while applying heat.

          Comment

          • IamPritesh
            Badcaps Veteran
            • Aug 2017
            • 354
            • India

            #6
            Re: Best Method to Align Small IC while replacing

            Originally posted by mcplslg123
            I use AMTECH flux. No i dont grip the ic while applying heat.
            This one ?
            https://www.amazon.in/Generic-O2IBG-.../dp/B01FA6G4B2


            What is Solder Paste ? I see in many videos,people are applying some grey paste like substance on the board before placing the IC.

            Comment

            • dellxps15
              Badcaps Legend
              • Feb 2014
              • 1588
              • italy

              #7
              Re: Best Method to Align Small IC while replacing

              soldering back a small qfn need to study the situation. if i remove for example a 3.3 5v ic, i use flux to remove it, and without clean old solder i go for the new one. when heating the board i then press a bit the ic on pcb. when all joint get connected ull see that the chip stay in place alone. if needed i keep a small pressure over it with tweezer till it get cold enought and soldered perfect. after that i use a small iron tips to pass all the corner and joint with flux and solder.

              if u remove an ic, then clean the board with flux and solder wick u can apply a small amount of solder on pins and center pin. then when soldering new chip use good flux, apply a good pressure on the chip till it get all extra solder out of it. keep pressing with tweezer till it cold down. with a solder tips remove extra solder from corner and get a pass on all side of ic. ur done.

              as for centering the ic, if u have a magnifier lamp with led illumination ull be just fine centering it perfectly.

              practice a bit and ull be the master of qfn soldering

              for flux i use kingbo but also amtech 559 (green bottle) is ok, but it need to be original, not fake.

              Comment

              • dj_ricoh
                Badcaps Legend
                • Jan 2013
                • 2073
                • uk

                #8
                Re: Best Method to Align Small IC while replacing

                Originally posted by IamPritesh
                This one ?
                https://www.amazon.in/Generic-O2IBG-.../dp/B01FA6G4B2


                What is Solder Paste ? I see in many videos,people are applying some grey paste like substance on the board before placing the IC.
                do you know what is paste? well, solder paste!

                PASTE -a thick, soft, moist substance typically produced by mixing dry ingredients with a liquid.
                Just cook it! It's already broken.

                Comment

                • IamPritesh
                  Badcaps Veteran
                  • Aug 2017
                  • 354
                  • India

                  #9
                  Re: Best Method to Align Small IC while replacing

                  Originally posted by dj_ricoh
                  do you know what is paste? well, solder paste!

                  PASTE -a thick, soft, moist substance typically produced by mixing dry ingredients with a liquid.
                  Why does anyone use this if we already have a good flux. Is solder flux enough?

                  Comment

                  • IamPritesh
                    Badcaps Veteran
                    • Aug 2017
                    • 354
                    • India

                    #10
                    Re: Best Method to Align Small IC while replacing

                    Originally posted by dellxps15
                    soldering back a small qfn need to study the situation. if i remove for example a 3.3 5v ic, i use flux to remove it, and without clean old solder i go for the new one. when heating the board i then press a bit the ic on pcb. when all joint get connected ull see that the chip stay in place alone. if needed i keep a small pressure over it with tweezer till it get cold enought and soldered perfect. after that i use a small iron tips to pass all the corner and joint with flux and solder.

                    if u remove an ic, then clean the board with flux and solder wick u can apply a small amount of solder on pins and center pin. then when soldering new chip use good flux, apply a good pressure on the chip till it get all extra solder out of it. keep pressing with tweezer till it cold down. with a solder tips remove extra solder from corner and get a pass on all side of ic. ur done.

                    as for centering the ic, if u have a magnifier lamp with led illumination ull be just fine centering it perfectly.

                    practice a bit and ull be the master of qfn soldering

                    for flux i use kingbo but also amtech 559 (green bottle) is ok, but it need to be original, not fake.
                    Thank you sir. That is very insightful.

                    Comment

                    • mcplslg123
                      Badcaps Legend
                      • Jun 2015
                      • 7262
                      • india

                      #11
                      Re: Best Method to Align Small IC while replacing

                      Getting a original flux is pain-most are chinese crap where some portion of the original flux is mixed with grease and sold as original. @pritesh, you are based in India and can buy it from Nehru Place,New Delhi instead of buying online. If you need contact info PM me, I'll give you contact number of vendors in New Delhi where you can get original Flux.

                      Comment

                      • KvnTM
                        Badcaps Veteran
                        • May 2018
                        • 434
                        • Germany

                        #12
                        Re: Best Method to Align Small IC while replacing

                        I usually draw the outline of the chip onto the board before removing it when there is no silkscreen. Surface tension of the solder will do the rest. Good flux is also very important.

                        Comment

                        • IamPritesh
                          Badcaps Veteran
                          • Aug 2017
                          • 354
                          • India

                          #13
                          Re: Best Method to Align Small IC while replacing

                          Originally posted by KvnTM
                          I usually draw the outline of the chip onto the board before removing it when there is no silkscreen. Surface tension of the solder will do the rest. Good flux is also very important.
                          Interesting. What do you use to draw the line that doesn't wipeaway when you clean the area before seating the new chip?

                          Comment

                          • KvnTM
                            Badcaps Veteran
                            • May 2018
                            • 434
                            • Germany

                            #14
                            Re: Best Method to Align Small IC while replacing

                            Originally posted by IamPritesh
                            Interesting. What do you use to draw the line that doesn't wipeaway when you clean the area before seating the new chip?
                            It really depends on the chip. Usually a normal pencil does the job and careful cleaning with a q-tip.

                            UV solder mask also works for this kind of stuff. It is available in many colors. It won't wipe away and is somewhat permanent. Just put tiny drops on the corners of the chip and cure it.

                            Comment

                            • jasko_jacker
                              Badcaps Legend
                              • Oct 2014
                              • 1137
                              • italy

                              #15
                              Re: Best Method to Align Small IC while replacing

                              I have tried many flux, I use three types:
                              Insat Hight Activity Rosin to remove bad bga
                              Insat VOC-Free water to inject under BGA for reflow
                              But the best for small component or reballing is
                              ERSA Fluxpaste F-SW 32, leaves no residue after the
                              welding, excellent activation point, even if only with
                              infrared

                              Comment

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