Compact PCB is not really suitable for hand soldering, 0805 parts would be way easier

[TzOk83]

If resistors and capacitors could be changed to 0805 footprint it would be way easier to hand solder them. Hand soldering 0402 parts is an extreme sport ;) I'm not saying it's not doable, but for sure not a piece of cake, even using a microscope. There is plenty of space on the PCB for bigger footprint parts, so I don't understand this design choice.

[retro16]

Hi, the compact PCB is not supposed to be hand soldered, but built with a stencil, paste and a reflow oven. 0402 was easier for an efficient layout and cheaper. I reckon there is enough room for 0805 and some of the decoupling capacitors are probably overkill, but I don't have motivation to change the design as EasyEDA made a big mess with parts updates so the source is practically useless as-is.

[TzOk83]

The main problem with hand soldering this board is that the GND pads of the capacitors are solid with the ground plane, which makes them very difficult to tin with a tiny soldering tip. I had to use a preheater and extra flux. But, at least for me, preheater means no microscope...

Stencil is a huge price increase, especially if you want to make just 1 or 2 units. I once saw the source project for a compact PCB, but it disappeared from the repository some time ago. I can try to make a reflow on my preheater, with paste applied directly to the PCB, without a stencil. Recently I managed to solder the TQFP100 chip that way and ended up with just 2 shorted pins.

[retro16]

The original EasyEDA sources for the schematic and PCB are the 2 json files in the pcb/Compact directory. That's what I used to produce all the othet files.

[TzOk83]

I'll look at them, but I've never used EasyEDA before. By the way, I may report a success in soldering ACSI2STM Compact PCB.

[methanoid]

So if we are recommended to order the boards assembled can you tell me if ordering assembled boards from JLCpcb they do the DB19 connector/pins? When I experimented with placing an order it didnt show in the render as being connected which suggests its not in the BOM/PickPlaCE files? It may be a "me" problem as never ordered from JLCpcb or PCBway before

[retro16]

When I ordered my units back in the days, the DB19 pins were properly soldered: I received the unit ready to use. Files provided in the source are the same files. I don't remember what was shown in the 3D render though, so I can't confirm what's happening on your order.
The pseudo-DB19 connector is made of 2.54mm pins soldered in pairs, if they are missing they are quite trivial to hand solder.

[BrettRogersUK]

I've used the provided sources for EasyEDA and changed all the 0402 components to 0805 and it fits well. I had to do a re-route on all all the tracks but it did it. I've ordered 5 boards so will see if they work when I've soldered them up. For the connector pins (DB19) would it be best to use the normal square dupont style header pins or Turned pin round header pins?

[retro16]

Very nice @BrettRogersUK.

About your DB19 pins question, here are my design criteria for the PCB assembly to help you take the right decision:

• All parts must be available for assembly at JLCPCB/LCSC, as it's one of the leaders for low cost PCBA so I want to keep that as a mandatory condition.
• Choose future-proof parts, as much as possible.
• Keep cost low.
• If you provide all files to the manufacturer, you should receive a 100% functional unit (no need to tweak anything). Firmware flashing using the "UART adapter inserted slanted in PCB plated holes" hack counts as a valid technique.

My opinion: of course, round pins are better for the health of the DB19 port, but square pins have the advantage of being much more common standard parts. There are also alignment issues during soldering operations, I like that square pins are tied together by groups of 2. Overall, I prefer round pins if feasible.

Since this change is about making hand-soldered units possible, we could add "hand soldering" to that list.

As soon as you tested the new design, feel free to do a pull request or share the design the way you want, I will review it and we could integrate it in the project. I can do the dirty work of regenerating gerber/screenshots/reference images myself.

[TzOk83]

The round "machine type" goldpins are much thinner, and I'm afraid they won't ensure proper contact in the DB19 socket.

I have just built the 2nd "compact unit", this time without the help of a microscope, but still with a preheater/reflow plate.

[methanoid]

Guys, you clearly are ALL miles better than I am with a soldering iron. But am I right that I can just send the Gerbers & BOM to JLCpcb and the 3D model and select them to manufacture and all I then need do is insert my SD cards? That seems too easy for a soldering-illiterate like me!!!!

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On Sun, 8 Dec 2024 at 18:55, Tomasz Orczyk ***@***.***> wrote: The round "machine type" goldpins are much thinner, and I'm afraid they won't ensure proper contact in the DB19 socket. I have just built the 2nd "compact unit", this time without the help of a microscope, but still with a preheater/reflow plate. — Reply to this email directly, view it on GitHub <#82 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABM6C3IQ774NG6P6ZKNXENL2ESI3BAVCNFSM6AAAAABSLIEI7CVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDKMRWGMZDOMZTGU> . You are receiving this because you commented.Message ID: ***@***.***>

[retro16]

@methanoid For the PCB, that's the idea. Sometimes some parts aren't available at JLCPCB so you need to substitute (which can be tricky). When I ordered mine, I tested the board as-is: flashed firmware using the "official" USB-UART dongle, plugged USB-C power and it worked first try.
The 3D model for the case isn't officially supported as I couldn't make it work 100% on all models, so I removed it from the official source, anyway feel free to experiment. IMHO the PCB protects itself pretty well from the environment so a case isn't 100% necessary.
Feel free to open a new issue if you have difficulties with ordering the parts or you are uncertain about the result, I have some time in the next weeks to help. Like other issues, provide screenshots, detailed info, ... you know the drill.

JM

[jfceklosky]

TzOk83

I created a fork of this design here, that works with the awesome firmware created by the team here.
All TH design and simple to build, but you need a working blupill.
I have had no issues with these from Amazon:

https://www.amazon.com/gp/product/B07VKSVM21/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&th=1

git