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    Reball Problem (BGA pad lift)

    Hi,

    I'm newbie in reball, so pls forgive me if technical words I use are wrong.

    What may cause the BGA solder pad lift before or after reball? I am having problems where solder pad lifted during removal of bad solder ball. It also occurred during reball, where the pad lifted after BGA been melted 2-3 times due to misalignment of new solder balls.

    My procedure of reball as below:
    1. Bake the BGA at 125 deg C
    2. Remove bad solder balls manually using soldering iron with solder wick
    3. Place new solder balls
    4. Reflow (I'm using hot plate to melt the balls due to limited space, so BGA might experienced sudden change of temperature from room temp to high temp)
    5. Inspection

    Any feedback would be appreciated. Thanks.

    #2
    Re: Reball Problem (BGA pad lift)

    Originally posted by hckeat86 View Post
    Hi,

    I'm newbie in reball, so pls forgive me if technical words I use are wrong.

    What may cause the BGA solder pad lift before or after reball? I am having problems where solder pad lifted during removal of bad solder ball. It also occurred during reball, where the pad lifted after BGA been melted 2-3 times due to misalignment of new solder balls.

    My procedure of reball as below:
    1. Bake the BGA at 125 deg C
    2. Remove bad solder balls manually using soldering iron with solder wick
    3. Place new solder balls
    4. Reflow (I'm using hot plate to melt the balls due to limited space, so BGA might experienced sudden change of temperature from room temp to high temp)
    5. Inspection

    Any feedback would be appreciated. Thanks.
    You are lifting the bga too soon and forcing it (not hot enough). That's why the pads are lifting, also when you are cleaning the bga pads with solder wick you are probably spending too much time trying to get them clean and you are over heating them, that causes the pads to lift also. Try to find some bga solder wick it's about 5mm wide, that will allow you to clean the bga pads with a couple of passes and don't forget to use plenty of flux you can never have too much. Look at the picture that I provided, that will give you an idea on the temperatures needed for the reflow process. When the temperature is at it's peak 250deg, you should be able to lift the bga with no problems. You can test to see if it's ready to be removed by lightly pushing it to one side. It should move and fall back into place by itself.
    Attached Files
    Last edited by opamp; 01-15-2013, 01:26 PM.

    Comment


      #3
      Re: Reball Problem (BGA pad lift)

      Originally posted by opamp View Post
      You are lifting the bga too soon and forcing it (not hot enough). That's why the pads are lifting, also when you are cleaning the bga pads with solder wick you are probably spending too much time trying to get them clean and you are over heating them, that causes the pads to lift also. Try to find some bga solder wick it's about 5mm wide, that will allow you to clean the bga pads with a couple of passes and don't forget to use plenty of flux you can never have too much. Look at the picture that I provided, that will give you an idea on the temperatures needed for the reflow process. When the temperature is at it's peak 250deg, you should be able to lift the bga with no problems. You can test to see if it's ready to be removed by lightly pushing it to one side. It should move and fall back into place by itself.
      Hi,

      Thanks for the feedback and profile, I'll try to use the method you suggest, hope it can solve the problems

      Comment


        #4
        Re: Reball Problem (BGA pad lift)

        can we share out profiles here?
        for remove bga my profiles is
        Air : 5
        IR : 180
        Top

        R1 3.00 R2 3.00 R3 3.00 R4 3.00 R5 3.00
        L1 90 L2 110 L3 140 L4 200 L5 240
        D1 40 D2 40 D3 40 D4 40 D5 40

        bottom

        R1 3.00 R2 3.00 R3 3.00 R4 3.00 R5 3.00
        L1 90 L2 120 L3 150 L4 210 L5 250
        D1 40 D2 40 D3 40 D4 40 D5 40

        Comment


          #5
          Re: Reball Problem (BGA pad lift)

          Originally posted by opamp View Post
          You are lifting the bga too soon and forcing it (not hot enough). That's why the pads are lifting, also when you are cleaning the bga pads with solder wick you are probably spending too much time trying to get them clean and you are over heating them, that causes the pads to lift also. Try to find some bga solder wick it's about 5mm wide, that will allow you to clean the bga pads with a couple of passes and don't forget to use plenty of flux you can never have too much. Look at the picture that I provided, that will give you an idea on the temperatures needed for the reflow process. When the temperature is at it's peak 250deg, you should be able to lift the bga with no problems. You can test to see if it's ready to be removed by lightly pushing it to one side. It should move and fall back into place by itself.
          And how to remove bga that have epoxy around and under it?!

          Comment


            #6
            Re: Reball Problem (BGA pad lift)

            Originally posted by tabbed74 View Post
            And how to remove bga that have epoxy around and under it?!
            It deppends a lot on the epoxy used. Sometimes you can get it off real easy, but sometimes it has a higher melting temperature than the solder itself. But what I recommend doing is heating the chip up a bit and trying to remove the outer glue with an X-acto knife. As for the one under the chip, well your best bet is just waiting until the solder melts and then taking the chip off normaly. You might need to force it a bit, but make sure that the solder is completely melted before forcing the chip off (btw forcing it shouldn't require a lot of force so if it doesn't move then the solder probably hasn't melted yet).
            Keyboard not detected, press F1 to continue...

            Comment


              #7
              Re: Reball Problem (BGA pad lift)

              When the temperature is at it's peak 250deg, you should be able to lift the bga with no problems. You can test to see if it's ready to be removed by lightly pushing it to one side. It should move and fall back into place by itself.
              You don't need to get to 250 as you can burn the chip. If it doesn't move when poked at 235C, you've got other issues there. Uneven heating (too little bottom heat), poor quality flux, things like that.

              As for lifting pads on the BGA when trying to clean them, you're probably using poor quality braid, or your soldering iron is not the right temperature.

              I would say it's due to the flux, as you mention that the pads lift from the BGA mostly when the balls have not attached on the first go. If you are using good flux, all the balls should attach on the first go, always.
              Originally posted by PeteS in CA
              Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
              A working TV? How boring!

              Comment


                #8
                Re: Reball Problem (BGA pad lift)

                Hi.

                This question is a little off-topic but is related because it can prevent damaging board with successively reworks.

                For a few years that I replace mostly graphics chips and have been wondering if there is any way to test a chip before soldering it to the board.

                I've come across several bad chips even since I stopped buying refurbished ones, and I want to prevent installing bad ones.

                What I thought about was some king of micro-conductive rubber that, in tests we could put between the chip (with or without balls) and the board and would conduct the electricity vertically where the balls and pads are located.

                I've got this idea remembering of the old mini-games that had one or two rubbers to supply power and signals to the LCD based on this functionality (older phones also used this method instead of flexes), but that where only one dimension (a string of conductors) and for this we would need two dimensions (a matrix of conductors) that would have to be much smaller than the ball/pad size, maybe about 1/5 of each conductor with the minimum space between them.

                Any ideas?

                Cya.

                Comment


                  #9
                  Re: Reball Problem (BGA pad lift)

                  Check this out for site cleaning https://www.youtube.com/watch?v=s38vQxXv0GE

                  If you are following that same procedure and still getting lifted pads then the BGA chip is degraded and will have weak pads

                  Comment


                    #10
                    Re: Reball Problem (BGA pad lift)

                    You are thinking of a test jig, the manufacturers do have them but most of us cannot afford them as they are quite expensive to make

                    There is however the ability to test the resistance of a chip, however finding the proper test points is another story

                    Comment


                      #11
                      Re: Reball Problem (BGA pad lift)

                      I think I may have already found the solution (didn't found many), but I'm still analyzing and requesting prices.

                      Comment


                        #12
                        Re: Reball Problem (BGA pad lift)

                        Originally posted by Th3_uN1Qu3 View Post
                        You don't need to get to 250 as you can burn the chip. If it doesn't move when poked at 235C, you've got other issues there. Uneven heating (too little bottom heat), poor quality flux, things like that.

                        As for lifting pads on the BGA when trying to clean them, you're probably using poor quality braid, or your soldering iron is not the right temperature.

                        I would say it's due to the flux, as you mention that the pads lift from the BGA mostly when the balls have not attached on the first go. If you are using good flux, all the balls should attach on the first go, always.
                        What is the temp that you use for the solder iron.
                        and what type of braid do you recommend.
                        The Night Drop Down, I Will Keep Try Until..., You Never know.
                        Dushi Kòrsou, Nos Tei.

                        Comment


                          #13
                          Re: Reball Problem (BGA pad lift)

                          First of all, what soldering iron do you have? Different irons have different thermal capacities and will need different set temperatures.

                          For braid, i'm sold on Goot Wick. It does an excellent job, especially when you add some more flux to it.
                          Originally posted by PeteS in CA
                          Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                          A working TV? How boring!

                          Comment


                            #14
                            Re: Reball Problem (BGA pad lift)

                            Originally posted by Th3_uN1Qu3 View Post
                            First of all, what soldering iron do you have? Different irons have different thermal capacities and will need different set temperatures.

                            For braid, i'm sold on Goot Wick. It does an excellent job, especially when you add some more flux to it.
                            I have the yihua 898d+ and sometime it pull some pad of, that is why i try to fine out what is the best temp for the iron, for the braid i use chem wik.
                            The Night Drop Down, I Will Keep Try Until..., You Never know.
                            Dushi Kòrsou, Nos Tei.

                            Comment


                              #15
                              Re: Reball Problem (BGA pad lift)

                              That looks like a generic Hakko clone iron. I have something similar, mine's the Gordak 936A. I use a setting slightly over 400C on the iron dial. You can try putting a thermocouple on the iron tip, it should be around 320C on the tip.

                              You haven't mentioned what flux are you using. Kingbo RMA-218 and Amtech NC559-ASM-UV are both good fluxes. However, i have found that what's sold as "Kingbo" is sometimes different flux, which isn't as good. With Amtech NC559-ASM-UV 100g jar i have found the quality to be constant. As for the braid, if it is the Chem-Wik i am thinking of, no wonder you are pulling pads off. That stuff is suitable for thru-hole work not BGAs. It is much too stiff. Try Goot Wick, it has finer wires and isn't as tight, so it sucks up more solder and slides more easily. Also try applying some flux to your braid before you start cleaning, it works much better that way.
                              Originally posted by PeteS in CA
                              Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
                              A working TV? How boring!

                              Comment


                                #16
                                Re: Reball Problem (BGA pad lift)

                                Hello everyone.i have an intel 855pm northbridge and i lifted 3 pad when i removed the chip, they marked as :Hi 8 ,Hi6 and Hi4 (in the diagram it's Hub Interface for cmos/I/O or simply hub interface .Are they vital or they are only testingpoints? And i can leave them ? I 'll very thankful if anyone can help

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