Is this a bad solder joint?

[Downtownandy]

I'm a total electronics noob. I can't tell if this solder joint is bad or if that stuff is something that's supposed to be on there. There are about 5 locations on the board that look similar.

[allaircooled]

If it was repaired recently it could be left over flux. A little bit of alcohol can clean that up. If not flux then probably what Joe Bob said.

[atcjorg]

It looks like flux get a q tip with alcohol and it should come right off use a magnifying glass to inspect solders and pcb

[atcjorg]

thats what i get for typing with 2 fingers I gotta pick up the pace

[porwolf]

Definitelz looks like rework or part replacement job with the solder flux not being cleaned up. The clean-up is not always necessary but better to prevent later corrosion. The printed circuit board underneath does not look like something got too hot there. Then it would look brown at that location. Cleanup with denatured alcohol will disolve the flux residue without harming anything. I use brushes for that.

[ischmitz]

This is a typical image of sloppy rework - either from the factory (yes, they too did some poor job back then) or by someone who isn't very familiar with PCB rework in general and has worked on the unit at some point:

During the soldering process flux is used to activate and clean the surfaces and prevent oxidation. Without flux the solder oxidizes and will not wet the surfaces. The result is a poor solder joint.

The flux is introduced a flux-core solder or in form of liquid flux. However, please don't use the same stuff that is used to solder the copper pipes on your water softener.....

If that flux isn't the right kind and/or left in place it will damage the PCB. I often get units that have been worked on and I see evidence of wrong soldering temperature, wrong solder, or wrong flux.

BTW: Our DME have cracked solder joints from age and vibration. These cracks cause electrical problems and intermittent failures. The no-spark is a typical result of a cracked solder joint.

A cold solder joint is caused when the soldering happened at the wrong (too low) temperature or with equipment that wasn't able to maintain the initial tip temperature. It will make the joint appear dull and brittle and have poor contact. Cold solder joints happen right away during the manufacturing process.

Wikipedia has a pretty good article with images showing the different issues you can run into.

Ingo

[2147cs]

Looks like resin flux ....residue ... should not be a problem.

[dicklague]

Originally Posted by 2147cs

Looks like resin flux ....residue ... should not be a problem.

rosin flux methinks.

[Downtownandy]

Thanks guys. Yeah my dad said it looked like it was just flux. Just confirming with the experts.
I am having intermittent issues but not a no spark. I put a screw driver in a plug wire and got spark. But my car does die at idle and has a rough time starting if it's not nice and warm. Took it to a technician to diagnose and he said replace the crank sensor, so that's what I'm doing tomorrow.

[DRONE]

The ones at 7 o'clock (pic. #3) look like the solder in the holes are missing( no flow thru).
The 1 in the 2nd pic. at 11 o'clock again no flow thru. solution would to be to re-solder them. In pic. #1 apply a solder wick to the big blobs to bet them down to correct size
the bigger the blob the better the job will not work on circuit cards

[SoCalSK8r]

Those are for mechanical attachment- notice there is not a copper pad there.

Originally Posted by DRONE

The ones at 7 o'clock (pic. #3) look like the solder in the holes are missing( no flow thru).
The 1 in the 2nd pic. at 11 o'clock again no flow thru. solution would to be to re-solder them. In pic. #1 apply a solder wick to the big blobs to bet them down to correct size
the bigger the blob the better the job will not work on circuit cards