From prototype to production - Page 1
Forum section: electronics / general

author: redgear
author_rank: Frequent Contributor
timestamp: September 26, 2020, 04:29:36 pm
content: I am finally ready with my product to go for a small volume production run(~400 units). This is my first project that's going to production.I have never had formal education in STEM. Everything I learnt is from this forum and internet. So go easy on me if some questions are stupid.The PCB is not really complex. A AC-DC powersupply module, a relay, a mcu and a 7 segment display. The power that the PCBs will handle is also very less ~40W.I know many would suggest me to hire someone to do it. But I want to do it myself and take this as a learning.1) Where do you guys get the PCBs assembled from? Chinese manufacturers like JLCPCB are really cheap but I have read many people posting that they would never use for anything series. Does that mean I should never get PCBs from chinese fab houses for production?2) When the PCBs arrive how do you do quality checks? What makes one better produced than the other(tolerance, soldermask,etc)?3) How do I write test procedures?4) I am planning to use their assembly service from the chinese fabs. What are the failure rates like?5) Any advice/suggestions that you would like to give for a beginner.Thank you!

author: bob91343
author_rank: Super Contributor
timestamp: September 26, 2020, 10:00:58 pm
content: I have never done this so am not experienced. However I groan when someone says not to use anything from China. Sure they have had problems but they are much better now.The only thing I can think of that affects quality might be trace lifting, or bad vias. Sometimes poor solderability. If they are going to assemble it, you can ask for final test.

author: SMdude
author_rank: Frequent Contributor
timestamp: September 26, 2020, 10:13:36 pm
content: Before you jump into this, I note that you have a power supply module. Is this built by you or purchased in? If purchased, do they have their own EMC and electrical safety certificates?Has your complete product been EMC tested and tested for electrical safety?(EESS in Australia, not sure what it is in the USA)If using JLC, I'm pretty sure they have to have the parts in their stock to build the pcb's, so make sure they have the parts.

author: kylehunter
author_rank: Regular Contributor
timestamp: September 27, 2020, 02:37:17 am
content: Yeah as SMdude said, you have a potential issue with it being ACDC. I worry less about the EMC compliance (even though technically it's still required), and much more about safety.Since it touches AC, if in the US, you're required by law to have IEC/UL listing. If you don't, it's illegal to sell.

author: redgear
author_rank: Frequent Contributor
timestamp: September 27, 2020, 05:56:31 am
content: Quote from: bob91343 on September 26, 2020, 10:00:58 pmQuote from: SMdude on September 26, 2020, 10:13:36 pmQuote from: kylehunter on September 27, 2020, 02:37:17 amThank you.It is a purchased powersupply from Mornsun. It is approved for EN55032 and CIRSS/FCC Class B, IEC62368-1, UL62368-1, EN62368-1 and meets EN61558 (60335).JLCPCB has a limit of 30 boards for assembly, can you recommend other assembly houses that are cheap?

author: kylehunter
author_rank: Regular Contributor
timestamp: September 27, 2020, 01:33:44 pm
content: Quote from: redgear on September 27, 2020, 05:56:31 amOK, so the power supply module sticks onto your board? So AC power comes into your board, travels to the ACDC module, then you use DC for the rest of the board?The module helps, but since raw AC still touches your board, you still are required to have the entire unit certified.As for your question, I've heard good things fromhttps://www.7pcb.com/for assembly. We used to use them for fab but did start to have some quality issues.. They are located in Canada, but also do fab and assembly over in China.If you go with a "cheap" China assembly house, expect to have varying degrees of success. They tend to be really hit or miss most of the time.

author: redgear
author_rank: Frequent Contributor
timestamp: September 28, 2020, 08:22:24 am
content: Quote from: kylehunter on September 27, 2020, 01:33:44 pmYep. Ok, I will read up on it. Would you recommend getting a stencil and doing assembling components manually until we pick up some volume? How difficult will that be? I am afraid about orienting the parts properly, I watched youtube videos that use hot air + soldering paste, looks easy but most difficult task will to place the components properly.

author: rea5245
author_rank: Frequent Contributor
timestamp: September 28, 2020, 12:04:27 pm
content: Quote from: redgear on September 28, 2020, 08:22:24 amNo! Chinese factories might be "hit or miss" (though I've never had problems with them), but if you're unfamiliar with PCB assembly, you'll be far more miss than hit.- Bob