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LMC6001: How to wash the circuit Board after soldering?

Part Number: LMC6001


How to wash the circuit board of the transimpedance amplifier on the LMC6001 chip after soldering?

Especially interesting the input circuit at the place of mounted installation and the body of chip.
PCB material - FR4.
Flux for soldering - BGA Flux Plus 7019074 Nordson.

Is isopropanol OK?

Regards, Andrey

  • Hi Andrey,

    We are recommending to place the entire board in a ultrasonic bath in a given temperature, and agitate the solvent for a period of 20-30 minutes. After the part is thoroughly cleaned, you may need to bake the PCB at 60-70C for several hours to remove any water moisture on the PCB (we are talking about fA leakage levels). 

    I believed that BGA Flux Plus 7019074 Nordson is RMA based (rosin, solvent and a small amount of activator).  

    Regarding to the cleaning solvent in the ultrasonic bath, I think that different company may use different cleaning formulation. It is a DI water based, sometimes engineers add certain percentage of solvent mixtures, such as ethanol, IPA or other polar solvents. Let me ask our quality engineer and see if there is a standard cleaning formulation for 7019074 Nordson Flux Plus in an ultrasonic bath.

    If the flux is water soluble, the DI water in a warm ultrasonic bath will do. 

    If this is only IC that you have to clean in a PCB, you may clean it by hand, but it is difficult to remove all the residues. If you have pA leakage between pins, you may have issues. To clean it by hand, here is what I do. 

    1. Cover the PDIP pin area with a lab cleaning tissue.

    2. soak the tissues with IPA (isopropyl or ethanol), and use a soldering flux brush scrub the area thoroughly (in a circular motion). 

    3. Rinse off the excess residues with IPA solvent, blow dry the wetted area with compressed air.  You may use DI or distilled water to rinse any residues off PCB.  

    4. Inspect the cleaness under the microscope. 

    5. Repeat the above clean procedures until it is "clean". Of course, it is hard to tell, that is why ultrasonic bath is the recommended clean procedure.