Jeremy Rubin's Blog

Here you'll find an assorted mix of content from yours truly. I post about a lot of things, but primarily Bitcoin.

categories: Bitcoin, Shenzhen Journey.

Learning the Ropes

Shenzhen Adventure Day 5

Today we were again mostly in-house.

We kicked off the day with a lecture on how to use Altium (pcb design software) by Bunnie. Afterwards, we got lunch at this super awesome Thai restaurant right by our office (they have very filling lunch specials for 45 RMB / 7.25 USD). I was going to go to another restaurant, but it started to pour (seems to rain most days so far around noon).

After lunch, it was mostly just working time. Artem and I decided to go to Seg, the super large electronics market to get keyboards and mice so that we can easily use Altium. We got super side tracked in segbuy and ended up walking around for hours, but it was good because we also found inspiration in the millions of parts available there.

One funny thing I learned is that if you’re looking for a single item, and the manufacturer is selling high quantity, saying you want a sample is a great way to get one at a low cost, but it feels somewhat dishonest. Then again, Seg doesn’t feel quite honest either…

After burning far to much time visitng all 10 floors of Seg twice, we headed back to the office, did some work thinking about our designs, and then headed to dinner. Saquib and I decided to go to the restaurant we were going to go to earlier – it’s a vegetarian restaurant so we were pretty excited to be able to order anything off the menu! The place was a little bit dingy, but the food was pretty great and not too expensive – 52 RMB / 8.4 USD comfortably fed us both – usually vegetarian restaurants are pricey because of low demand. Was pumped to finally be able to eat the famous ma po tofu! After dinner we went to Gong Cha, a tea chain. Their teas are awesome, I had a kumquat limeade drink with pearls and jelly that was super refreshing. Desipite being cheap already, they had a buy one get one half off thing going so we got 2 large drinks for 22 RMB / 3.5 USD.

I also learned that the word “chisu” I’ve been using for vegetarian sounds a lot like “chizou” which means stall. That explains why everytime I ask for vegetarian food they show me the bathroom. Could have been worse! I think the right word is “su-shi”.

Toy Prototyping Factory Tour

Shenzhen Adventure Day 4

We visited a toy studio for a to-be-unnamed toy company (hence, no photos). This place was really cool. Basically, big brands (and not just for toys, clothes, electronics, etc) spec out a thing they want at a very high level, such as “make me a toy that looks like a turtle”. They then send it to a prototyping studio who makes a turtle toy prototype and sends it back for feedback. So the brands essentially monitor markets and tell the protypers what to build to meet it.

Assembly Line Factory Tour

Shenzhen Adventure Day 4

At the AQS plant we also got to see the final assembly of a printer. This was really awesome. Printers are super complicated builds so they basically have to be done by hand. Essentially what happens is they have stations with a couple of tasks on them. A person performs the task, scans a barcode on the item, then passes the cart to the next person. There were 100-200 stations for this printer. The barcodes let them make sure each printer has had all steps and also lets a control center monitor to make sure that they are on point for meeting the quota for that day and hour. What’s cool is that each station has an instruction booklet which sets the task. The entire line is essentially a very long pipeline, so they have to carfully balance the pipeline to prevent bottlenecks and keep throughput high. It takes multiple revisions to get it right. Apparently setting up such a line, from end to end, is 3-6 months. Each printer is also fully tested.

Automated Board Population/SMT Factory Tour

Shenzhen Adventure Day 4

We got to go to AQS to see one of their board population/smt lines. This was fucking awesome.

  • Solder Paste Machine

  • SMT Machine

  • Pick and Place

  • Inspection

  • Touch up

  • Solder machine ( a pool of solder grazes the board)

PCB Factory Tour

Shenzhen Adventure Day 4

First they hand check the design to conform with their capabilities. They will make minor changes if necessary.

Next they drill out any holes needed in the boards. They very frequently check the bit quality, and bits are only used for 3000 holes before being swapped out.

Next they do some electroplating stages

Here they do the photo chemical processing steps that are light sensitive

Then they do silkscreening (I’m missing a picture of this…)

Next is depanelization, or cutting out the individual boards from the panel.

Finished boards

Next they have Quality Control:

  • Chemical checks that boards have the correct properties

Inspecting the boards quality visually, they cut out a chunk of board, encase it in resin and then grind it down to the edge

They also digitally check every single board for continuity/impedance.  This machine essentially has two needles it touches between each point to test,

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