Preparing a Hikaru BGA Chip for Re-installation

    • freddiefiasco wrote:

      Oh gotcha. When I am tinning I can't tell if it's the right way or if I'm missing something.
      Are you using rosin flux or water soluble?

      I'm new to the reball process and your thread is helping me deal with the gotchas I'm encountering. :)
      I'm still learning the process too. Luckily I have a Hikaru pcb with damaged pads that is worthless so I have been testing on it. Some things I've learned:

      Clean the pcb good before applying the Kapton tape. If you don't it will not stick and will warp during heating. This is bad because it will create heat pockets under the tape that will damage components. I exploded a bank of 6 caps in this manner. When tinning the pads I would use a no clean flux. Water soluble is probably ok as well. Do not use RA flux on the chip. It's too messy and is unnecessarily hard on the pads when cleaning. You may get away with reballing the chip with a water soluble flux. However, DO NOT use water soluble flux to reattach the chip to the pcb. You need a flux that is semi-tacky that will hold it up during the process and help keep the chip in place.

      Make sure it's a paste flux for reballing and reattaching.

      What are you learning to reball?
    • Mitsurugi-w wrote:

      freddiefiasco wrote:

      Oh gotcha. When I am tinning I can't tell if it's the right way or if I'm missing something.
      Are you using rosin flux or water soluble?

      I'm new to the reball process and your thread is helping me deal with the gotchas I'm encountering. :)
      I'm still learning the process too. Luckily I have a Hikaru pcb with damaged pads that is worthless so I have been testing on it. Some things I've learned:
      Clean the pcb good before applying the Kapton tape. If you don't it will not stick and will warp during heating. This is bad because it will create heat pockets under the tape that will damage components. I exploded a bank of 6 caps in this manner. When tinning the pads I would use a no clean flux. Water soluble is probably ok as well. Do not use RA flux on the chip. It's too messy and is unnecessarily hard on the pads when cleaning. You may get away with reballing the chip with a water soluble flux. However, DO NOT use water soluble flux to reattach the chip to the pcb. You need a flux that is semi-tacky that will hold it up during the process and help keep the chip in place.

      Make sure it's a paste flux for reballing and reattaching.

      What are you learning to reball?
      Nothing specific, just wanting to have this type of skill under my belt. I just barely learned how to perform drag soldering with SMD. My next goal is mainly aiming at a few Radeon chipsets that are relatively easy compared to the hikaru. Baby steps in this case because I do not yet have all the proper equipment so when I get to a step that needs a specific item, things are on hold.
      I am getting the same issue with exploding caps in the vicinity of the GPU core. I think the temp is too high and also the amount of time and depth of the heat. I will double check my numbers and see if I am getting consistent.

      Is the water soluble flux considered no clean or is that a whole different type of flux? I've only seen resin flux, the kind that crystalizes at room temps.
      From what I have learned, water soluble flux is recommended if dealing with high impedance. I'm not sure if any of the items being used for our processes so I dunno.
      Having two different types of flux will be something I need to keep in mind during practice.