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# Reflow Workshop: A Journal
Status: updating
## 2023-03-15, Wednesday
Today I took a group interview for assistants of a new hackerspace. Five
students were present, in a room with Mr. Xiao, the manager.
My prior work experience bought me some credibility, and I shared with
Xiao my frustration not being able to properly do electronic engineering
for lack of resources.
We then took a walk in the empty hackerspace. The proper name is actually
Tang Junyuan Student Innovation and Entrepreneurship Center, but I prefer
hackerspace.
▲ This is only half of the hackerspace.
We had a heck of a time discussing what this space is potential of.
Four-wheelers. LaTeX and vim workshop up the stairs. And of course
— reflow soldering.
Reflow soldering is on my [list of life goals](../random/life_goals/), but
it's in my dream since 2019. At that time I was a nobody in high school.
All I could solder was through-holes. Kliment, my IRC friend (though we've
met IRL once) kindly mailed me one of his works: [an electronic
kitten](https://github.com/kliment/catws). It is 5cm×5cm.
▲ It purrs when you stroke it right; otherwise, it hisses.
## 2023-03-16, Thursday
So I revealed my plans to Kliment, who was very supportive as usual. He
forwarded me an email listing the things I need.
One crucial thing is that I have to program the <abbr
title="microcontroller unit">MCU</abbr> before soldering, so I need
a <abbr title="Quad-Flat No-leads with 32 pads">QFN32</abbr> test socket.
Kliment estimated it to cost 800 RMB, but in China it seems to only be
~200. I bought one for 180.
## 2023-03-17, Friday
Just ordered the two parts from LCSC with specific numbers: Murata
PKMCS0909E4000-R1 and Meihua MHS110FRGBCT. LCSC gave me a 20 RMB coupon.
After that I went to look for the MCUs (ATtiny88-MU) and found them in
a random Taobao store that sells them at 7 RMB apiece. I think I might
need other chips later, so I also added some ATtiny48 and ATmega328PB to
my shopping cart. I asked customer service if they got any in stock. They
said I could just place my order, so I did.
Then I went to hunt for the PCB and stencils. Kliment forewarned me that
factories use only one stencil per assembly line, so my use case is
extremely rare. I will have to consult the manufacturer for a quote.
## 2023-03-19, Sunday
Talked to the sales rep of JDBPCB, they were confused for a good minute,
then realized what I was asking for. They told me to just place my order.
They claim they had seen this kind of thing before. Kliment suggests it
might have been [Honza Mrazek](https://honzamrazek.cz/).
Sent <abbr title="basically a zip file of everything the factory needs to
produce PCBs and stencils">Gerbers</abbr> to them, along with my requests
in the notes. They PCBs are approved.
## 2023-03-20, Monday
I received the piezo speaker and RGB LEDs from LCSC today.
To my surprise JDB approved my stencil request, and priced it at an
unexpectedly low 80 RMB.
Later the customer service approached me to confirm once again that
I wanted 10 copies of the same stencil. Upon hearing yes, they revealed
that the 80 RMB was actually the price for *one* stencil, but for me they
could do 216 RMB for 10, tax included, with the implication that I do not
do this kind of shit to them again. They fear me.
Kliment helped shave off 46 RMB off my budget. I was looking for
a hotplate which he said will not cost more than 80 RMB. When I told him
best I could find is 135, he said I was looking for the wrong thing; what
I need is not a hotplate advertised for solder work, but a consumer grade
for heating food and beakers. I changed the keyword and found one at 89.
## 2023-03-21, Tuesday
Cell batteries, holders, and the QFN32 socket have arrived.
▲ \*Kneels on floor\* \*Unlids socket\* \*Presents brand new ATtiny88-MU\*
Will you marry me?
The socket is a delicate piece of hardware. You would place the MCU in
a 5mm×5mm slot where two adjacent pins are 0.5 mm apart, and access them
from a <abbr title="Dual In-line Package">DIP</abbr> interface where that
distance (also known as the lead pitch) is 2.54 mm.
The microcontrollers on the other hand haven't even begun shipping yet.
I asked them what's wrong, and their answer was: "we don't have them."
…Then don't sell them?
I then asked when they will be back on stock. They read my messages but
remained silent. Chances are they will never ship, says Kliment. This is
just a scam on a chain of fake distributors. The evening they finally gave
in, offering a refund.
At the same time I'm looking for more trustworthy vendors. Kliment
referred me to Winsource. Although a Shenzhen company, they don't seem to
ship to China under that brand. So I reverse engineered a bit to find that
its Chinese trademark is 聚源鑫. Small company, not super well-known, not
even a store on Taobao. I'll talk to them in working hours tomorrow.
I am currently inside an episode of self-doubt. What if I fail to learn
reflow myself? Even if I can barely manage, what qualification do I have
to teach other people? Perhaps I should have picked my battles and went
for a simple SMD hand soldering workshop instead. That's much much easier,
and I have done this three times.
## 2023-03-22, Wednesday
As I rose from bed I realize I could have ordered 5 stencils, and
organized two or more sessions in series. But I guess 10 is ok. Especially
when imbursement is possible.
Was busy most of the day, and I forgot to contact that shady vendor.
After dinner I moved what I have got so far to the hackerspace with my
bicycle.
▲ It was a 2.5 km ride.
In the empty hackerspace I unboxed the hotplate:
▲ They sent along a *physical* invoice, a rare item these days
## 2023-03-23, Thursday
I rang 聚源鑫 to ask about the availability of ATtiny48-MU, the cheaper
alternative to 88. They don't have any.
Now that the hope of getting chips from shady sources has vanished,
I returned to LCSC to check out their offers. They are able to act as
a broker between me and Mouser, charging 12.87 RMB apiece. Sounds good.
I ordered 20.
## 2023-03-24, Friday
The much awaited stencils are here! They were sandwiched between two
pieces of pretty rigid cardboard. The PCBs are in the same box.
▲ For scale, each stencil is 5cm×5cm
## 2023-03-25, Saturday
The major chunk of my BOM is taken care of. Now we shall focus on the
nitty bitty discrete parts, such as capacitors and resistor packs. As
always they are extremely cheap.
Last time I forgot to give LCSC the invoice info eligible for
reimbursement, so this time I ordered 20 more piezo speakers with the
info. Totally necessary and not abusing the hackerspace funding.
## 2023-03-26, Sunday
The discrete parts have arrived.
Also I brought all the tools I have from home: multimeter, soldering iron,
solder, flux, etc.
## 2023-03-27, Monday
Mouser seems to have shipped the MCUs.
In other news, I found this beautiful graphic that would make a great
poster background:
▲ Credits: [Shapo on pixiv](https://www.pixiv.net/en/artworks/91199411)
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