Electronics > Manufacturing & Assembly

Pick and Place Assembly Line - How bad could it possibly be?

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Mangozac:

--- Quote from: Cerebus on September 05, 2021, 11:52:13 pm ---"What's happening under that BGA package?" <- That's why X-ray.

--- End quote ---
I know what the x-ray is used for; I was wondering why he felt the need to add it in at this point. If they've been assembling boards by hand successfully with no x-ray it's not exactly a requirement yet. I know plenty of people running SMT lines and doing BGAs without x-ray.

matthewpang:
Initial post updated :)


--- Quote from: Mangozac on September 06, 2021, 12:30:32 am ---
--- Quote from: Cerebus on September 05, 2021, 11:52:13 pm ---"What's happening under that BGA package?" <- That's why X-ray.

--- End quote ---
I know what the x-ray is used for; I was wondering why he felt the need to add it in at this point. If they've been assembling boards by hand successfully with no x-ray it's not exactly a requirement yet. I know plenty of people running SMT lines and doing BGAs without x-ray.

--- End quote ---

Question of what the time is worth right - in our case we're a consulting engineering company and our clients are billed hourly. With a lot of the latest parts only available in BGA plus the increase of WLCSP and even RF Modules with pads that cant be inspected (MDBT50Q and other NRF52 modules are a popular example) PLUS high layer count PCBS (lots of thermal mass) - many hours are spent debugging a sufficiently complex board only to discover one (or more) of the un-inspectable parts has an issue.

Also assuming after a day or more of hunting - you find a problematic BGA - all you can do is to rework it and pray it worked right (which isn't necessarily a good bet).

X-ray rapidly becomes justified (saving ourselves the frustration, and our clients a lot of $$$) .

For example - we recently had a board for a customer that passed 100% of its functional tests. However - there was an unexplained increase of 400uA in current draw of just some of it's sleep states. Having enough dynamic measurement range to go from ten microamps in deep sleep all the way up to amps in wake is really hard. We only caught this after quite some substantial debugging (there was a partial short defect under the BGA of one of the ICs that had a nontrivial impedance and only showed up when said IC turned on some of it's peripherals. While the uC and Joulescope et al try to solve this problem - it is *very* hard to do this if you also need higher bandwidth/sampling speed and are using a device that will get upset from the range switching.  This is in fact so hard to do that the test gear company in question wont let us say how we took the measurement as it's in an upcoming product.

Many many days of work and a lot of expensive equipment would have been saved if we could have just x-rayed the board because the moment we did it showed up. By the way - reworking this board would have caused the issue to go away, never to be found until it showed up in some small % of units in mass production (there was a small inefficiency in the component footprint and solder mask that increased the probability that this would happen)


--- Quote from: jmelson on September 04, 2021, 11:50:43 pm ---Well, the machine arrived generally in working condition, but then things started breaking.  After getting into the disk drive, it was apparent that the machine had not been powered up in at least 6 years, and likely was left sitting in unconditioned space in Austin, TX.  So, a humid soak. 
Jon

--- End quote ---

Yeah definitely hear you there, we purchased all our machines via reputable refurbishers for this reason. Definitely paid more - but it's worth it for the time and better peace of mind.

Reckless:
If you need any GSM parts let me know I have a truck load based in chicago along with a UIC GSM for sale and a GSM GENESIS LIGHTNING dual head dual gantry machine for sale.  Tons of gold, black, green feeders for sale to go with genesis.  I love my Essemtec ovens and have extra one for sale in case anybody wants to follow in OP's footsteps.   Essemtecs are the best IMHO (small, compact and precise).  Ive had one Ekra semi automatic it was nice but haven't played with any of their automatic machines.  My tech likes his Ekra E5. 

salihkanber:
Wauv thats a bit of a long text :)

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