how would you color solder
 

say you have some molten lead free solder.

How would you turn it blue or red or black or whatever?

while it's molten ?!?!?

lead melting point is relatively low
but as soon as you start adding whatever coloring chemicals into the mix, the melting point will increase and either it solidifies or the added stuff burns off, or the lead becomes so inpure that it's no longer lead

but that's just my uneducated guess here...

i'd wait for it to harden then try a paint pen.

lead free - hmmm. The melting point would still be too high for organic pigments so you would have to use a metalic oxide. Too much might change the conductivity if it was to be used in electronics unless it was balenced out with silver flake...

It can be done.

thanks. it has to be colored when poured. wish I could use lead, but the lack of toxicity is important.

i majored in organic chemistry 20 years ago, but of little help other than maybe this read?

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described with reference to the following examples. The present invention, however, is not limited to these examples.

EXAMPLE 1

When hexaborate lanthanum (LaB6) was employed as a colored powder compound:

Approximately 10 grams of hexaborate lanthanum powders (deep indigo blue) with a grain size of 300 mesh or less were added to 100 grams of solder cream (containing 10 wt./% flux) consisting of eutectic solder powders with 300-400 mesh grain and mixed fully in a manner that does not destroy the configuration of the solder powders.

The colored solder cream thus obtained was printed onto the land of a printed wiring board and reflow soldering was carried out at a temperature of 220° C. after mounting a chip component thereon. After solidification of the soldering, a deposition membrane consisting of hexaborate lanthanum and flux was formed on the surface of the soldered portion. Said deposition membrane appeared as a very deep and vivid purple color.

EXAMPLE 2

When neodymium oxide (Nd2 O3) was employed as a colored powder compound:

Approximately 10 grams of neodymium oxide (light blue color) were added to 100 grams of solder cream (containing 10 wt./% of flux) consisting of eutectic solder powders with a grain size of 300-400 mesh and mixed fully in a manner that does not destroy the configuration of the solder powders.

The colored solder cream thus obtained was printed onto the land of a printed wiring board and reflow soldering was carried out at a temperature of 220° C. After solidification of the solder, a light blue deposition membrane consisting of neodymium oxide and flux was formed on the surface of the soldered portion. Said deposition membrane had the characteristic of a clear and distinctive outline when exposed to ultraviolet rays.

EXAMPLE 3

When neodymium fluoride (NdF3) was employed as a colored powder compound:

Approximately 10 grams of neodymium fluoride (light purple color) were added to 100 grams of solder cream (containing 10 wt./% of flux) consisting of eutectic solder powders with a grain size of 300-400 mesh and mixed fully in a manner that does not destroy the configuration of the solder powders.

The colored solder cream thus obtained was printed onto the land of a printed wiring board and reflow soldering was carried out at a temperature of 220° C. After solidification of the solder, a thin deposition membrane with a pearlescent white color consisting of neodymium fluoride and flux was formed on the surface of the soldered portion. Said deposition membrane had the effect of preventing metallic sheen on the surface of the soldered portion.

According to the present invention, since the colored powder compounds included in solder cream are deposited onto the surface of the soldered portions forming a deposition membrane, occurrence of halation due to metallic sheen can be prevented, thereby enabling the carrying out of accurate appearance inspection either by visual inspection or by automatic optical inspection apparatus.

The accurate carrying out of appearance inspections as afforded by application of the present invention improves the reliability of solder wettability inspection. Furthermore, the addition of said coloration powders prevents the occurence of solder ball and solder bridge, and protects the soldered portions from environmental conditions due to the formation of a surface membrane.

http://www.patentstorm.us/patents/5650020-description.html

Lead fee eh?
You're just asking for a solder joint failure, if you ask me.

hate the stuff.

it won't be used to join anything

mightmake for some pretty top coats on joints though

Solder not used to join something? Hmm, must be for some sort of decoration then or to conduct electricity.

candy apple red.

Ornaments for the clothing line I imagine.