Solder from Hell

[ian]

I'm assembling a multitude of PIC driven boards for a product. I get some help
from various people to do the soldering. So one of my guys suddenly starts delivering
blobbed solder, burnt traces, crappy boards. I threaten to cut him off so he tries
harder but keeps delivering crappy boards. I bring him in for "remedial" solder
training. As I use the solder he bought, it doesn't flow, it blobs, and the board is
terrible. I crank the heat on the iron but it doesn't help.
Some of the boards are transistor-relay driver boards and the relays pull in but
don't release. After some frustrating troubleshooting I find stray current pushing its
way into the base of a resister grounded transistor-driver base . I clean the board
with flux cleaner, alcohol, and the stray current goes away.
Many of the boards made with this solder had to be scrapped.
I know there are different "types" of solder but what kind of solder is this? All
I find on the otherwse normal spool is a Lot #. I didn't know ANY kind of solder could
cause problems like this.

Ian

[Bob Scott]

The solder might be 40/60 solder instead of the 60/40 or 63/37 resin core mix for electronics. 40/60 solder is for soldering rain gutters or plumbing. I saw one spool of 40/60 for sale at a Fry's store, an obvious error by the store's buyer. Pity the guy who tries to solder his boards with that stuff! Or, maybe your solder is some type of lead-free solder. (?)

In any case, your solder is the wrong kind. It should at least announce the alloy mix on the spool and the core (resin or acid) if any. For more info, look up "solder" in Wikipedia, the great holy source of all knowledge.

[haklesup]

non flux cored solder on a board with oxidized copper traces will do this. Even if it is flux cored, adding either paste or liquid flux almost always results in better solder flow and adhesion. You should always wash new boards whether you use additional flux or not. Uncleaned boards are a hallmark of low quality and cheap assembly (see it in chinese made goods all the time)

WHat is the surface on the PCB? (bare copper, gold, solder {AKA HASL}, tin, etc) Are you sure it isn't lead free solder? For lead free, it's both a little higher in temp and longer dwell time.

[reloadron]

I would only add if you have the manufacturer and the lot number you could call the manufacturer and ask exactly what it is. Possibly something went wrong with that specific lot number or it was not marked correctly. If the boards haven't changed and the board prep hasn't changed then that pretty much leaves only the solder.

Ron

[MrAl]

Hi,


I would have guessed lead free solder too, but then it could just be the wrong type as mentioned
in some of the other replies.

What to do:
Go out and pick up a roll of solder from somewhere where you know should be selling good solder,
then test that, or even give it to the guy that you say isnt doing too well with soldering.
See if that helps. If you see a marked improvement, you know what to do next.