PCBA Quality Issues



  • Dear Staff of Duet

    I just received my Duet 2 WiFi yesterday and because I work in electronics I check every PCBA I order.

    I was quite shocked when I noticed multiple traces of SMD rework, minor (acceptable) SMD offsets, unsoldered lead, solder ball and a blowhole on the bottom side. I started to question I'm dealing with a genuine board.
    With your reputation, professionalism and high end motion controller boards this build quality is just not acceptable. It's not your fault though. I suppose the board been built by a company you contracted with, but either way only your reputation is at stake. I haven't powered the board yet but the more I read the documentation the more I like it.

    Issues are:

    Rework should not be done on SMDs especially not multiple times on a single board. If there is some problem with the SMT Pick and Place machines (improper offsets, decentralized device pick up) then that needs to be resolved otherwise it may just get worse.

    Device offset (even if its acceptable) is a good indicator that something haven't been configured properly on the SMT machines. When the PCB goes through the reflow oven, melted solder pulls these devices on the pad. So basically these offsets was worse before they got reflown.

    The unsoldered lead doesn't seem to have evidence of wetted fillet.

    Solder ball on one of the TMCs lead is acceptable, but not professional.

    The same applies to the blowhole.

    I seems THT components have been soldered with a wave solder oven, but rework is evident on the following: Expansion header, Z A, Power In and USB.

    Blowhole might be an improper moirsture sensitive device (PCB) handling issue. (TMC-s and basically most IC-s are MSDs and can delaminate when they go through the oven while having moisture in them. They might even pass the tests and fail months later. Quite rare but possible.

    Tough my board is functioning and passed tests it may stop working later because of these issues. Also no evident fillet is a defect by all classes of the IPC standard.

    Images

    How can we resolve this issue?

    Thank you


  • administrators

    I am concerned by your report, but unfortunately the images you posted are not accessible to us. Please host them in a public area.



  • @dc42 Sorry my bad. Forgot to make the folder public. It's accessible now.


  • administrators

    Thanks. I don't deal with production issues, so one of my colleagues will get in touch with you.



  • @dc42 Ok. Thank you



  • Hey @Wardialer look around the large extension connector, does the PCB seem bent to you?



  • @frank26080115 It didn't seemed bent but I will check when I get home. THT components seemed flat to the PCB but I didn't take a good look. I can also take a look at the logs on the SD card for date and time if needed for traceability.



  • @frank26080115 The PCB is flat. According to the log I found on the SD card logging started on 18.02.2019. 15:15:12. Also forgot to tell the board is from ooznest.

    Images2

    Images taken by phone.



  • Thank you for drawing these assembly shortcomings to our attention. Please advise the Duet serial number - sticker on MCU - so we can identify the board and raise these issues with the assemblers at once. We would then like to replace your board with a new one and return it to the factory as detailed evidence of unacceptable practices. Please email info@duet3d.com so we can set this up.



  • I didn't complain about this because the printer works fine and I've done a good suite of tests, but I took this picture of my slightly bent PCB a few months ago

    alt text



  • @roland Thank you. I will get in contact.

    Also if I can advise an electronic manufacturing company, there is one in Hungary called Katek Hungary Kft. I don't know their prices, I only worked there (I live in the UK now), but they're top quality and they even make class 3 boards.

    Some info:
    Component, process, operator level traceability (every board, component reel is labelled with bar- or QR code and gets scanned into a database; operator has to log in in order to work and also has to take responsibility to their deeds, so no mistakes are allowed) Innotech stencil screen printer, with full solder paste inspection device on all boards (microns with 2 decimals accuracy), full AOI inspection on all boards with independent operators (they report even indicators to SMT operators, even the smallest offset gets corrected), 2% scrap/rework rate (if it reaches 2% the line gets halted, can be restarted only by quality), proper moisture sensitive device handling, THT, many test equipment, and so on...
    But maybe its enough if I say there is a gate that only lets you in if you're ESD protected.
    Also it's not noticeable if they rework something, they do it by standards.

    Never seen more professional company like them. No board with defects get out of there.

    Maybe it worth's a call especially for Duet 3



  • @roland Thank you for your outstanding support


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