projects/reflow-workshop: 2023-05-11 update

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@@ -226,6 +226,16 @@ isopropyl alcohol, but "industrial alcohol" on the marketplace refers to
 methanol. The customer service kindly suggests I look for "industrial
 ethanol". I ordered 500 mL.
 
+## 2023-04-02, Sunday
+
+Today I made what I consider one of my best designs with Inkscape.
+
+!["TECHJI REFLOW WORKSHOP", but the "O" in "REFLOW" is shaped like an IC
+chip and there's a via next to the
+"W"](img/reflow-workshop/reflow_workshop_title.png)
+
+▲ The font is Orbitron.
+
 ## 2023-04-03, Monday
 
 The Japanspachtel are here. I headed to the hackerspace and did a partial
@@ -431,3 +441,123 @@ Both the magnifying glasses and spray bottles are here.
 ## 2023-04-15, Saturday
 
 I got the 20 PCBs and the invoice for everything I ordered from JDB.
+
+## 2023-04-26, Wednesday
+
+After a week of final exams, I took a few days off to relax, before
+rediscovering the existence of reflow workshop.
+
+It's spring break right now and I'm at home. At this point everything
+seemed ready, but an inventory check reported a lack of cell batteries and
+holders. So I ordered a bunch more.
+
+## 2023-04-28, Friday
+
+I went back to uni to pick up the package. I also went to two concerts
+where I caught a guitar pick.
+
+## 2023-05-06, Saturday
+
+I discussed workshop arrangements with my colleagues at TechJI. It will be
+held twice on both evenings this weekend.
+
+## 2023-05-07, Sunday
+
+Behold, the final poster design:
+
+![From top to bottom: anime girls pic, "TECHJI REFLOW WORKSHOP", PCB
+renderings, 5/13-14 18:00 唐君远, and credit for the
+illustration](img/reflow-workshop/poster.png)
+
+▲ Despite the visual effect, most of the graphics is not my own.
+
+## 2023-05-08, Monday
+
+I drafted the promotional article to be published on WeChat.
+
+## 2023-05-10, Wednesday
+
+### Afternoon
+
+The article is published, but WeChat decided that hyperlinks are not
+allowed. Among them is the survey we use to register participants.
+Sabotaged by WeChat's pointless restrictions.
+
+I received messages asking for the link, but I can't edit the article
+(thanks WeChat), nor can I post it in the comments without approval (many
+fucking thanks WeChat). I ended up urgent pinging the admin, who
+thankfully made it public real fast.
+
+The moment link went public applications blew up. In two hours we had 32
+applicants. We can seat at most 19, because we only have so many ATtiny's
+left. This means I'll have to send rejection letters to so many people.
+I've always hated rejection letters. Now I've become what I swore to
+destroy.
+
+Conclusion: Tencent is a horrible asshole whose sole purpose is to destroy
+the open internet.
+
+### Evening
+
+I made a horrible mistake. I made applicants fill in their cell number,
+and stated that I will contact them via SMS or WeChat. HUGE mistake. I had
+to manually copy the numbers to my phone. Should have asked for email
+instead.
+
+## 2023-05-11, Thursday
+
+I went to print the poster on an A2 sheet of paper. It's pretty!
+
+![Poster in a giant printer](img/reflow-workshop/poster_printing.jpg)
+
+▲ The exposure is _just_ long enough to blur the print head, which I think
+makes the photo way more dynamic
+
+I cycled to the hackerspace to hang it up. It's much smaller than all the
+other posters, but it's hands down the prettiest.
+
+After that we had an internal training session within TechJI. The purpose
+is to familiarize ourselves (including me, because the last time I did
+this was one month ago). We started with an overview, then we smeared
+solder paste. Everyone had their own technique. The common trend is too
+much paste, and/or going over one place too many times. Everyone had to
+rework at least once, because that is essential knowledge for the
+workshop.
+
+Who could apply paste the best? We have a winner!
+
+![Paste in the right places on the QFN
+footprint](img/reflow-workshop/perfect_qfn.jpg)
+
+▲ This is a sign that they are better at it than I am
+
+Up next we had pick-and-place. Sadly we can't offer a complete kit to
+everyone because we need to leave enough for the 19 people. Two of us were
+actually among the 19, so we decided to make two prototypes.
+
+I demonstrated C1 and C2 (the two 0805 caps), and made a few comments on
+the polarity of the diodes, pins of the QFN, and the 0402 region where you
+make a recognizable pattern so you know which board is yours on the
+hotplate.
+
+No one had any trouble. I inspected the result which is shockingly great,
+then turned on the heat.
+
+One of them is observed to have two shorts on RN2, and the other is
+flawless. However, when we put a battery in it, the RGB LED (D6) doesn't
+turn on. Why not? It turns out D6 was upside down. It is indeed very
+subtle, and even I failed to catch that before heating. Then I noticed the
+same problem on the other board. With a soldering iron I manually fixed
+them.
+
+It's time to test our products. Weirdly, one works, but the other is
+really bad-tempered for some reason. Whenever you remove your finger from
+the battery, it hisses nonstop. I would advise it to see a therapist.
+
+I asked Kliment what could be the reason, and he suggested it was either
+a short on the MCU or the resistor packs, or a shoddy battery holder,
+because the kitten hisses when reset.
+
+To my disappointment I only ordered 100 LEDs, which is _barely_ enough.
+And to an electronic engineer _barely_ enough is not enough. We have to
+keep a redundancy, so I ordered 200 more.