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I need to be able to solder wires to the hidden pins of an smt ic. The ic is soldered directly to the pcb, and they are not visible. I need to access the PCM audio interface on a sim7500e, and the only way to do that would be for me to solder wires to the pcb, then resolder the sim7500e. Does anyone know how to do this? For reference, here is the prototyping module I am using.

Thank you for any help

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  • \$\begingroup\$ Do you even have the equipment to desolder it in the first place? Or solder it back? \$\endgroup\$ – DKNguyen Jan 14 '20 at 20:20
  • \$\begingroup\$ This looks like it has a very low probability of success to me. You would probably have more luck just redesigning the module. \$\endgroup\$ – Elliot Alderson Jan 14 '20 at 20:25
  • \$\begingroup\$ I don't see you being able to do this without a reflow oven/plate setup. The chip is too big for hot air (without some kind of special hood), in all likelihood you are going to end up damaging the chip taking it off, then it will never sit flat trying to get it back on with wires underneath it. \$\endgroup\$ – Ron Beyer Jan 14 '20 at 21:17
  • \$\begingroup\$ thanks everyone, I was trying to avoid redesigning the module because the sim7500e is nearly £30 each, so for a hobby it gets pretty steep pretty quickly. \$\endgroup\$ – user240198 Jan 14 '20 at 21:22
  • \$\begingroup\$ The sim7500e has an LGA package, which usually means most of the traces are visible and accessible even though the pins themselves are hidden. The exception would be pin-to-pin connections routed under the chip. Is this the case here? If this is PCM interface it has to be interfaced to something else on the PCB, has it not? \$\endgroup\$ – Maple Jan 14 '20 at 21:49

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