Professional assembly mishaps

[Leo Bodnar]

Just a few of those sweet little things UK assembly houses did to me over the years... 

I had hundreds and hundreds of rejects.  And then there are stories... Quite a few of stories.

These are all from ISO9000 certified UK companies.

Leo

[Kean]

That first one!!! 

[dave_k]

These are all from ISO9000 certified UK companies.

That merely assures the quality of the mishap...

[nanofrog]

These are all from ISO9000 certified UK companies.

That merely assures the quality of the mishap...

Seriously though, they qualify for the    award IMHO. 

[Mattylad]

The first one, could this redefining what is called "flip chip" ? lol

All signs of very poor assembly and testing control.

[SeanB]

ISO9000 just means all will have the same defect, not that all will be perfect. Looks like they were literally using a chip shooter in there for some.

[Yellofriend]

These are all from ISO9000 certified UK companies.

ISO900* just means they have a quality procedure. You can send them the pix and ask them to follow up with a 8D report.

Looking at the images, the only one I would worry about is the last one, because it could be a serial error.

[Leo Bodnar]

Angry PnP machine programmer...

[Leo Bodnar]

Today's scoop.

[dmills]

That shit happens,
I have had completely wrong values (Apparently the reel was mislabelled!).
Wrong way around, especially good fun with tants....
1mm pitch FPGAs where the tray had been fumbled and they were randomly twisted on the paste, oh how we laughed.

Completely upside down is a new one on me however, how the hell??! 

Then we come to the fun that sometimes follows when the assembly house decides to monkey with the paste mask before getting the stencils made (And without asking first), very annoying.

Assembly houses are pretty much a case of 'who has pissed you off least recently'. They all allege to do AOI, I think the AOI machine is sometimes the intern.

Regards, Dan.

[fcb]

So no AOI?

Even my non-ISO9001 (or anything) local CEM has AOI - it's not perfect (current favourite is it won't pick up SOT223's with a leg bent upwards) but close to it.

Great to see someone else using TagConnect also.

[dmills]

Oh everyone has AOI, it just seems to be a real fiddle to get it to reliably pick up some things.

Regards, Dan.

[Leo Bodnar]

We had panels with scorched AOI stickers on them.  I guess it tells you something.
Leo

[xani]

That first one!!! 

¯\_(?)_/¯

[mikeselectricstuff]

I've seen upside down SOICs - even had it with my own machine.
Probably a mis-pick or slipping on the nozzle, dropping & bouncing.
Or just from a tube, starting teh wrong way up.
Also not impossible that it was taped upside down.
 

[fcb]

We had panels with scorched AOI stickers on them.  I guess it tells you something.
Leo

Implying they did the AOI BEFORE reflow??

[sokoloff]

ISO9000 just means all will have the same defect, not that all will be perfect. Looks like they were literally using a chip shooter in there for some.

"Before implementing ISO9000, we occasionally made crappy products. After ISO9000, we consistently make crappy products!"

[Leo Bodnar]

One of the assembly houses also kitted some boards for us.

The first batch had 175V MMBD1404A diodes replaced with 30V BAT54C diodes. 
Of course, all of them promptly and consistently blew up after application of 50V bus.

Second batch had fake TDK components  from Alibaba (the only place in the whole world I could find the fakes on) that fell off the board because tin plating was shit. Assembler assured me that all the components are genuine and have traceability certificate.  I got very excited and asked for a copy.  I got it (below.)

I rang TDK, they just yawned and fell asleep, didn't even want to see the samples.

I got a copy of the assembler ISO9001 certificate and rang the guy at BSI who signed it.  He was the most "bored at work" guy in the world.  Complete lack of any interested, wasn't even sure if there is a process of revoking ISO9000 certification.

In the end I have given up on trying to make them lose certification and moved on from them, nobody is taking ISO9000 seriously anyway.
From recent conversations with friends who are still using this particular UK company - the show still carries on.

We now went through 8 assembly companies and there are only two who did not screw us up [yet.]

You'd think I made it all up.  I wish I did.

Leo

[Yellofriend]

Second batch had fake TDK components  from ....

A very good way to test for fake ICs is X-ray. Many assembly factories have one for BGA use.

Typically the leadframe for one IC never changes, fakes usually do not use the same leadframe. Dice size will be different too. That's how I identified a fake Maxim CAN bus IC.

To ask a factory to buy parts for you is always extreme high risk. Buy everything yourself from Mouser etc., that is the safest way.

[T3sl4co1l]

To ask a factory to buy parts for you is always extreme high risk. Buy everything yourself from Mouser etc., that is the safest way.

Depends on who you're asking.  I regularly do design with a local company; they are, in turn, part of a global CM.  They have good procedures in place.  For example, for a proto run, they only buy exactly what you specify (mfg+pn, if not supplier too).  I have seen mistakes in protos, but they're more easily attributed to lazy employees than bad procedures or management I think.  The managers are always interested to know about mistakes.

I've seen a couple of the failures shown above.  Never seen a flipped chip.  Have seen poor soldering, or missing paste.  Usually they spot these and do rework.  Most of the faults I've seen are either my fault (a poor footprint, in turn because the drawing is poor or I missed something), or avoidable with my help (e.g., ensuring adequate soldermask web width between pads, to prevent shorts on paste and wave steps -- closely spaced, untented vias is one I didn't expect to see, but it seems to happen regularly on lead-free wave).

I've also seen variable results, like the mfg cell nearby usually does nice work, while the one in the next state sometimes makes errors.  So there's probably some variation in local culture, as well as employee performance.  Which is probably about as good as you can expect.

Tim

[Leo Bodnar]

Duh, speak of the old devil Murphy.  Got this from a customer just this morning. No idea how we got this through but of course we are rushing a replacement.  Luckily this happened once for 70k+ devices.

It is impossible to do extensive functional test on each and every board, essentially double-checking what assembly house should have done. If it's assembled properly it will work fine. This is why having a trustworthy assembly partner is critical for us.

Leo

[mikeselectricstuff]

Duh, speak of the old devil Murphy.  Got this from a customer just this morning. No idea how we got this through but of course we are rushing a replacement.  Luckily this happened once for 70k+ devices.

It is impossible to do extensive functional test on each and every board, essentially double-checking what assembly house should have done. If it's assembled properly it will work fine. This is why having a trustworthy assembly partner is critical for us.

Leo

You can see how that might pass AOI but definitely a test-coverage issue if it gets out the door

[Leo Bodnar]

You can see how that might pass AOI but definitely a test-coverage issue if it gets out the door

People who assembled this showed me how their AOI system works.  It did stop and alerted operator if it could not correlate package markings with the reference.
I assume that either operator just cancelled and let it through or AOI was simply not done.
Leo

[mikeselectricstuff]

To ask a factory to buy parts for you is always extreme high risk. Buy everything yourself from Mouser etc., that is the safest way.

You'd think that  a CEM is in a good position to provide value by combining orders, getting qty discounts etc. but IME it doesn't tend to work out in practice, at least for the low volumes I typically do.
They  basically pass on their cost plus what they charge for procurement, and have little incentive to find better prices as you're probably already committed to them. They also like to combine all costs so it's hard for you to tell what part of the cost is parts, assembly and setup.
Same situation for things like stencils - they just buy teh same large stencils form the place they've used for years and pass on the cost, despite the the fact that you can get them for a fraction of the cost from China, or for a small run, tape up a much smaller stencil into their frame.
 
I've yet to meet a CEM that shows any passion or enthusiasm for what they do, or any significant amount of imagination.

[CJay]

We had panels with scorched AOI stickers on them.  I guess it tells you something.
Leo

Implying they did the AOI BEFORE reflow??

Or that they reworked it