Your thoughts on wave soldering?

[canidoit]

This technique seems to be used for mass production of electronics equipment and I was wondering what people's thought are of this technique?

Are they prone to bad solder joints as the product that uses this technique gets older and possibly be the cause of most electronics failure?

Has the technique improved, that only those electronics from a certain period would likely be problematic.

I have read that some earlier Reel to Reel machine were prone to issues due to wave soldering being used.

Any thoughts?

Thank you.

 

[gyraf]

I've never seen an error that could be attributed to wave soldering - however, don't get me started on hand soldering

That said, my commercial stuff is still hand-soldered (and -mounted) by myself

/Jakob E.

 

[porkyc]

Wave solder process..................more efficient, no residual flux, far less problems.

 

[JohnRoberts]

Wave soldering is a mature process and reliable when done properly. Of course there are process constraints and things like PCB layout can affect results.
With mass production problem layouts generally reveal themselves and get corrected.

Back last century at Peavey I had some SKUs selling over a thousand per month. Wave soldering helped made that possible.

JR

 

[ccaudle]

what people's thought are of this technique?

Primarily useful for through-hole joints, so rarely if ever used in the last several years.

Are they prone to bad solder joints as the product that uses this technique gets older and possibly be the cause of most electronics failure?

No, the problems show up right away, typically either poor joint fill in the hole, or splashes stuck between pins. Commercial equipment I was familiar with always had an inspection and clean up station (originally manual, later computer vision based) to look for those problems and correct before the equipment was powered if found.

If a partial hole fill is not found for some reason it could result in failure later after thermal cycles and vibration, but that would be down in the noise, nowhere close to "most" failures.

Has the technique improved

Lead free solder does not wet as well, so does not flow into the holes well. That combined with most components changing to small spacing smt packages has effectively ended the use of wave solder for high volume products. Maybe someone is still using it for things like xlr connectors which aren't easily available in smt. All the products I deal with professionally have smt or press-fit connectors, so I'm not sure what current practice is for something like a USB interface with xlr which is mostly smt but has just a few through hole connectors.
Benchmark Media had a video showing that they put in xlr connectors by hand soldering, but I think they are pretty low volume compared to something like a Focusrite interface, or a Yamaha or Midas stage box.

 

[JohnRoberts]

Back last century we used both SMD and TH technology on small mixers. I believe SMD on the top side of the board survived a pass through the wave solder line to solder TH components.

JR

 

[pucho812]

At my last gig, not my current one, it was mainly thru-hole parts and wave table on new units. Any rework was hand soldered. Of the over 3000 units made each year, we had 1 where a solder splash stuck causing a stereo unit to go into mono. So less than 1%.

 

[Vetsen]

I’m not aware of any problems specifically associated with wave soldering. Lead-free does flow enough for wave solder. There are many alloys that are lead-free that can work better for a wave process. I would argue that it’s easier to get good barrel fill with a wave process. I’ve seen some parts get too hot while being waved in a lead-free wave process.

I have found that wave solder doesn’t sound as good as hand soldered

-Vetsen

 

[S.Samuelsson]

Hi.

Tldr:
While wave soldering has its undeniable and sometimes unavoidable issues and pequliarities, there's not much that can be done to avoid bumping into it when dealing with mass produced commercial products.
Resoldering or reflowing the suspected solder joints -even before there's any issues- is fast and easy.

This technique seems to be used for mass production of electronics equipment and I was wondering what people's thought are of this technique?

When done correctly, opens up a world of possibilities, when done incorrectly/sloppily, pretty much nothing but grief.

Are they prone to bad solder joints as the product that uses this technique gets older and possibly be the cause of most electronics failure?

IME yes.

Especially if there's components with different mass legs, and/or both TH and SMD components.
Both cases can be -and have been- done even with lead free solder, but not everyone seem to have the needed know-how.
Or they just don't care.

Lead free solder is also likely to suffer from metal fatique failures if there's vibration or thermal expansion/contraction.

Has the technique improved, that only those electronics from a certain period would likely be problem

Yes and no.
There's been quite a few improvements (as well as setbacks) over the decades wave soldering has been used, but since the soldering process is only one link in a rather long chain of events, it'd be somewhat unfair to single out just the soldering process used and/or certain time period(s).

That said, the first years of RoHs in the turn of the century are IMLE the worst.
Sure, there's been botched up wave soldering attempts before and after, but if I had to choose one period in time, that'd IME/IMO be it.

There was (and unfortunately seems to be) IMLE a lot of teething problems when lead free solder was introduced -and then forced- into pcb soldering process regardless of the soldering method, and while some were technical, most were at least partially financial.

I have read that some earlier Reel to Reel machine were prone to issues due to wave soldering being used.

Quite possible.
Wave soldering is not particularily well suited method when making a relatively small batches of pcb's, but it absolutely shines when there's tens- or hundreds of thousands well engineered pcb's to be soldered and the process can be fine tuned to perfection.

After all, without wave soldering we wouldn't have our smartphones, tablets, PCs, etc.

Regards,
Sam

 

[totoxraymond]

It's been reliably used for through hole designs for a long time and still is.

But it seems wrong set up can leave parts of the PCBs with not enough solder / bad solder joints.

Last year, my 7 yo induction cooker went crazy and suddenly couldn't start. It was due to a bad solder joint on one of the mains relay. It took 7 years, but the solder joint finally burnt and was not doing its job anymore. I repaired it in a few minutes (mostly time for my iron to get hot).

After some research, i found out that it was a default present on the whole series of cookers. I could see a small area on the PCB that clearly didn't get as much solder as the rest of the PCB, so i reflowed all the area just in case.

Thomas

 

[CJ]

Wave solder with lead free is no good for large parts ,

I have to resolder all the pots on a guitar amp board as cracks and voids are a constant problem.

When you run a large batch of boards you have to watch your solder tank level. Boards done at the beginning of the run will do fine but if adjustments are not made for the tank level dropping then the last batch of boards will need a lot of touch up.

A big wave machine sure stinks up the place, flux and solder , not a healthy job , even with all the ventilation.

 

[12afael]

when I used to work at darkglass we used SMD mixed with through hole(pots, Leds, switches,etc. ) we used a technique called selective soldering. it is something I never heard before and it work well when you don´t have too much through hole stuff. or when you need to mount stuff that you can´t put on the wave machine. it have a nozzle of molted solder and can go pin by pin.

 

[Rusan]

In the early 90s, I got a free original TS-808 Tube Screamer courtesy of wave soldering. A buddy gave me his when it quit working, along with the instructions, "Fix it if you can, or else throw it in the trash. Either way, you can have it." A quick examination revealed some iffy solder joints, one of which had finally failed. I remelted them, and it worked perfectly. I still have it.

I know that such anomalies represent less than 1% of wave-soldered electronics, but back when I was repairing music electronics as a side job, it seemed as if that entire 1% landed on my bench. I found a bunch of 'em in music store brand gear over the course of time, especially one very popular brand which shall remain nameless.

 

[ccaudle]

I know that such anomalies represent less than 1% of wave-soldered electronics

It could be higher for low priced designs. My experience was primarily with equipment which sold in the US$1000 range and had generous warranty support, so the manufacturing line had full time engineers responsible for monitoring manufacturing quality and making appropriate adjustments.
That level of care may not be possible when building devices which sell for $100 or less.

 

[pucho812]

I have found that wave solder doesn’t sound as good as hand soldered

-Vetsen

oh? This I have to hear. I never noticed an issue between wave soldering and hand soldering of the same pcb’s with the same parts. Unless you consider the wave machine being faster and a possible band joint with hand soldering.
What’s next you are going to tell me how you can hear a difference between smt and thru-hole of the same circuit and layout?

 

[JohnRoberts]

oh? This I have to hear. I never noticed an issue between wave soldering and hand soldering of the same pcb’s with the same parts. Unless you consider the wave machine being faster and a possible band joint with hand soldering.
What’s next you are going to tell me how you can hear a difference between smt and thru-hole of the same circuit and layout?

the winky emoticon suggests it was offered as humor....

===

There are known differences between SMD and TH components but I wouldn't make broad sweeping generalizations... read the spec sheets.

JR

 

[CJ]

Yes I have noticed a bit better sound from a mini tube screamer (surface) over the standard size which is through hole. But they might have tweaked the circuit or it could be the layout (smaller area, different trace routing) that is making the slight difference.

 

[JohnRoberts]

When designing mixed technology SMD/TH mixers I noticed we could just about fit the entire mic preamp underneath the XLR jack.. Smaller/tighter layouts are generally a good thing.

There are issues with extremely small SMD parts having voltage coefficient issues but these are relatively easy to identify and avoid with bench testing.

JR

 

[Newmarket]

fwiw the boards from my day job are generally either mixed or all thru hole. Problems are possible / experienced with SMT reflow too. Thru Hole parts are generally hand fit. And it is often required to be so due to High Voltage considerations - essentially no spikey bits and nice well rounded solder joints to minimise partial discharges.

 

[abbey road d enfer]

It seems nobody mentioned the fact that a few PCB's had to be sacrificed before achieving optimum settings. Not a big deal when you intend to produce several hundreds of PCB's but not so good for low numbers.