Flux remover

conntaxman

what is the best way to remove flux on solar cells after soldering.
tks
John

BB.

Re: Flux remover

Don't they typically use no-clean flux? Although, perhaps water clean flux would be better.

But Google is great--Ask it what type of flux to use on solar cell tabs:

Solder fluxes facilitate solder wetting by dissolving the oxides present on the surface of the tabbing ribbon as well as the silver metallization bonding stripes on the top and bottom of the solar cell. Typically liquid fluxes consist of a chemical activator package, rosin or a synthetic resin and a solvent system.

The solar industry has historically used fluxes formulated with alcohol solvents, but newer formulations are available formulated with low VOC solvents. These newer low VOC fluxes are safer to use and have less environmental impact.

In both electronics assembly and the manufacture of solar cells, long term reliability is of paramount importance, and care must be taken to insure that the flux selected for soldering will be non-corrosive. It is important the activator/resin system be designed to volatize or decompose during the peak temperature of soldering. This insures that no corrosive by-products remain, and therefore the flux residue can safely remain on the substrate. Such fluxes are known as "no-clean" and the formulation technology and reliability testing were developed for electronics assembly and microelectronics applications by flux manufacturers serving these industries. In these industries, circuitry line width and spacing are significantly less than used in solar cells and even minute amounts of corrosive residues negatively impact on SIR (surface insulation resistance) performance. Therefore it is prudent for the module assembler to select a tabbing ribbon flux supplier that also supplies to the electronics assembly and microelectronics industry.

Kester #186 flux pen seems to come up a lot for solar cell soldering projects.

Otherwise, I just use lots of isopropyl alcohol (or similar) to clean rosin flux (although, there are probably better chemicals). Flush the area well (with light scrubbing) and let dry (at least for general circuit board cleaning.

I believe crystalline solar cells are OK with distilled water (at least for short periods). Some folks use water to float the wafers away from the rest of the stack (to reduce chances of breakage).

-Bill

RCinFLA

Re: Flux remover

90% isopropyl alcohol is best available.

If you have or can get tricholoroethane (Carbon Trichlor) it is the best.

niel

Re: Flux remover

if one can get 100% alcohol that would be best as this eliminates some impurities from being deposited. trichlor is nasty stuff, stay clear of that one if you can. methyl ethyl ketone (mek) could also be used, but it too is a bit on the nasty side. of those 3, trichlor is the only one that is non-flammable.