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cold solder joints, what causes failures?

VQLT

VQLT

Active Member
I have a universal dvd/sacd/dvd-audio player. It was mid-top of the line from yamaha last year (model dvd-s2500). well, after owning this unit for 17 months it froze up and none of the functions would work. the local yamaha tech said it was a failed cold solder joint. he was not sure of the cause.
does anyone know what could cause this? (heat, vibration,etc.?) I want to make sure it does not happen again
 
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It is caused by a bad soldering job. on eot two things:

Movement after removing the heat source.
Not getting both parts up to reflow temp, and the solder doesn't really adhere.

Nothing you can do to prevent it, it is factory quality control.
 
well, yamaha definately needs to work on their factory QC. I'm hoping they show a little sympathy and treat it as a warranty repair
 
If it's a modern piece of mass produced equipment, then it was most likely a machine that made those solder joints. A human being may have looked it over (quality control). Sometimes it is the same solder joint that goes bad on several units. Then again it could be just one of a kind. In any case, you definitely should get proper consideration as a customer.
 
Anyone care to guess where it was made? Almost certainly not in Japan. My dollars are either China or Korea. Lots of "QC? We don't need no steenking QC" junk swims over from there.

Yet another reason to buy classic gear whenever possible. The race for cheap manufacturing has rendered QC nearly meaningless for most mid to low end consumer goods. The laptop I'm pounding away on right now was made in the land of fortune cookies and it shows they don't give a damn about QC. It left the plant with a DC power jack that didn't work unless the jack was in "just right". Its not just a labor issue. The jack itself is a cheap piece of crap.

As for solder QC issues, IMHO its due to untrained people running complicated equipment like a wave solder machine. If QC was on its toes, they would catch it and make manufacturing get the machine running correctly before another piece left for assembly. Too bad rejecting a run of mainboards would kill the profit margin. What the hell do you expect for $50?

Back to your original topic, doesn't it piss you off when formerly great companies like Yamaha and Sony slap their name on some cheap Chinese BPC without any regard to its quality or the damage this does to their brand name?
 
VQLT said:
I have a universal dvd/sacd/dvd-audio player. It was mid-top of the line from yamaha last year (model dvd-s2500). well, after owning this unit for 17 months it froze up and none of the functions would work. the local yamaha tech said it was a failed cold solder joint. he was not sure of the cause.
does anyone know what could cause this? (heat, vibration,etc.?) I want to make sure it does not happen again
Click to expand...

Short answer, it is out of your control. The cold solder forms "clumps" that will fracture easily generating intermittent connections that will drive computer controlled equipment nuts (inoperative).

Short of manually re-soldering EVERYTHING, you can do nothing AND IF there are "chip" type components, the clearances are so small that manual resoldering will just destroy it.
 
Causes for solder joint failures (not comprehensive, but does cover the top group):

  • Set up of the wave or reflow solder machine
  • Improper sizing of component holes or solder pads
  • Aged/oxidized solder
  • Solderability of components or circuit board
  • Vibration during solder process
  • Shock (physical or temperature) during shipment or storage
  • Improperly formed component leads
  • Flexing of circuit boards, after soldering (during test or assembly)
  • Insufficient contact between component and PCB (solder making connection)

Enjoy,
Rich P
 
With modern production techniques, the parts are not individually hand soldered. Rather, the parts are all installed on the board, and the board is dipped in a solder bath. No, not dunked, just the bottom of the board. It is all done at one time.

It is easy to have a bad solder joint. Sorry, that is the way it is.

But also a solder joint can fail for other reasons. For example, a receiver I have on my workshop now looking for a new home... it would play a few minutes to half an hour and cut off. Then cut on all by itself, and off.

Turns out that a high wattage resistor in a section of the power supply that fed +/- 12 v to power IC's in the preamp had a bad solder joint. It was probably good when it left the factory, but years of heating up, cooling, heating, cooling, finally fractured the solder joint, the wire lead loose in the middle of the solder. Finally, add a little corrosion due to age, movement from thermal expansion, and you have an intermittant connection. It happens. FINALLY I located the bad solder joint, desoldered with braid, removed the resistor, cleaned the leads with fine sandpaper, tinned, resoldered, and all is well. It has been test played for some time now with no problems.
 
Yamaha agreed to cover the repairs under warranty. I can't complain about the service. at least not yet
 
Most likely, it was a ring crack, not a cold-solder joint. They occur when a component heats up and its wire leads expand, then contract when it cools. This stresses the solder that lies between the wire and the circuit board, and it breaks. It is a very common failure mode. I have seen failed industrial equipment with nearly a hundred ring cracks, due most likely to manufacturing plant heat and vibration. Conditions are much better in your house, but it is likely that the problem will eventually reoccur. I had hoped that the new surface-mount technology would reduce or eliminate the problem, but apparently not.
 
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