Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


No-clean, water-based flux residues after wave...

Views: 1481

#57930

No-clean, water-based flux residues after wave... | 2 February, 2009

Hello everybody,

We are running a product through wave solder process using three different PCB suppliers. I have noticed that you can see more flux residues (water-based, No-clean flux) on one supplier than on the other two. All three PCBs run under the exact conditions, if not simultaneously.

Any ideas on how to address this situation? is there something that the PCB supplier is missing?

Thanks in advance for your help.

George

reply »

#57942

No-clean, water-based flux residues after wave... | 2 February, 2009

Questions are: * What are the soldermasks used by your three board suppliers? * What tests have you run to assess the compatibility between these three soldermasks and your flux?

reply »

#57947

No-clean, water-based flux residues after wave... | 2 February, 2009

What flux are you using? We use a low-solids No-Clean water-based flux. Maybe some of what you are seeing is not residue from the flux but is from reaction with the solder mask.

reply »

#57952

No-clean, water-based flux residues after wave... | 3 February, 2009

Hi George, I would suggest you to re-look your process parameters, especially for the pre-heat temperatures and the amount of flux deposited. The mask properties and that of your flux also play a role, but you could zero down to the root cause after you validate your present process parameters. Many years ago, I too had faced the same problem. At that time I re-validated the wave soldering process for Operational Qualification and Performance Qualification. Trust me, the problem was resolved.

Cheers! - Sachin

reply »

#57970

No-clean, water-based flux residues after wave... | 3 February, 2009

The spec for all PCB suppliers is "solder mask over bare copper using LPI on external layers (green)". The flux we use is No clean 270WR flux (AIM). As far as process parameters, like I mentioned before, same parameters for several suppliers, only one shows more flux residues (or solder mask reaction to the flux as Stephen said)...

Regards, George

reply »

#57973

No-clean, water-based flux residues after wave... | 3 February, 2009

Hi George This is down to the different cure temperatures used during PCB process. No problem with the flux or your settings You should be seeing a waxy greasy oil like substance on the dirtier board. Or the resist has absorbed the flux residues not allowing them to volatise off properly. Try to increase the initial preheat to volatise off the water carrier before it gets absorbed into the resist hope it helps Cheers Greg

reply »

#58002

No-clean, water-based flux residues after wave... | 4 February, 2009

Your specification for all PCB suppliers of 'solder mask over bare copper using LPI on external layers (green)' is broad and open to the use of material from many possible LPI suppliers by your board fabricator. In at least one case, it appears that your flux and a soldermask are incompatible.

reply »

PCB Cleaning

Boundary Scan