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PCB Assembly Service - How do they get the components of your design?

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  • PCB Assembly Service - How do they get the components of your design?

    I have a question related to the assembly process when you order this service to any PCB manufacturer company. So my question is, where do these companies get the componenes? I mean, imagine the design you send them has 5 different ICs from 5 different manufacturers, do they buy the ICs you need to the manufacturer, do they buy it to the supplier you specify on your BOM, or do you have to send them the specific components you want for them to assembly it?

    And also, I was wondering, when I create a new component I associate it to a part number of a specific supplier (normally Digi-Key), but what is the point on doing this if afterwards when you order the assembly service of a PCB company they won't probably have the same components of Digi-Key?

    I am quite confused with all this process... any help is welcomed!

    Thank you in advanced!

  • #2
    It depends ....

    - One company I know always buys all the components and will send PCBs + components to Assembly house.
    - The company where I used to work had a board manufacturer in china - the manufacturer in china helped with components but there still were some components what had to be handled by our purchasing department.

    For mass production, there is always a lot of communication around buying components, there is no magic, always problems, new numbers, replacements, etc. For mass production, when you are buying thousands of components, any 1 dollar increase / decrease is influencing your expenses / saving in thousands of dollars - so you really would like to do it properly and maybe have it under control as it can save you (or cost you) a lot of money.

    Some Assembly houses offer full service, so they buy the components, but I have only tried this once and we had a LOT of troubles. Assembly house bought all the components, build the boards and .... they didn't work. I spent hours trying to find out what the problems was .. it was a BAD COMPONENT and we had no idea who is going to pay my time and all the expenses to fix the boards. It was a nightmare ...

    PS: Also, If your boards have expensive components with long lead times, you may want to stock at lest these components - assembly house would not like to stock them, as they would have money tight up to that stock. Assembly house can supply stuff like resistors, capacitors, etc, that is not a problem, but other components are tricky.


    • #3
      Hi Robert,

      Thank you for your answer, it has helped me a lot to figure out how the assembly process work. So, how would you recommend to do the assembly for someone (like me) who is a particular and who wants to build only one board (or maybe 2 or 3, but not thousands)? My board has a lot of tricky components as it is a SMPS (specific transformer, specific control IC, specific transistors, ...) so I guess going for the full-service companies would be a disaster...

      Thanks again!


      • #4
        We buy all components and build 5-10 prototypes in our local assembly house, but it is not cheap (1000 - 3000 USD, depends on complexity + you need to buy extra components so they can feed them into machines). However, we do not have any other option - there are usually many BGAs and plenty of 0201 ... doing it manually would cost much more and quality would be low.

        However, we have built many prototypes by hand - if it is possible, we sill often do it. So if you can build it and especially if you are building only 1 prototype, you may want to build it by yourself.

        PS: Once I have been assembling an x86 board manually - took me full time 1 week of soldering


        • #5
          Ok, I think the best option for me is doing it manually :-) I don't have any BGAs or really small components on my design so I will try to assembly it by myself and hope for the best!

          Thanks for the adviece Robert!


          • #6
            If you are doing a lot of prototyping or even small runs it might be worthwhile to invest time/money in something like this:
            I have the fortune to have a reflow oven at my workplace... it saves a lot of time and headache


            • #7
              Seriez, nice, thanks for the tip!


              • #8
                Seriez great kit, I may consider buying one of those, the price is really good! Thanks for helping!


                • #9
                  I have that kit with a cheap IR oven from ebay (150-200€), it's a killer combination for low volume runs now that stencils are dirt cheap


                  • #10
                    xaviondono sounds like a great home-kit. If anybody knows of a good video explaining all this process (something like how to produce your own boards at home on a budget) it would be awesome to share it here... :-)


                    • #11
                      Maybe I could buy something like that and make a video ... I am making a note on my todo list


                      • #12
                        That would be great Robert!! :-)