This afternoon a DHL courier dropped a package at my doorstep. JLCPCB shipped it with a signature release required, but I waived the signature in advance.
I'm old enough to remember when placing a domestic mail order came with an "Allow 6 to 8 weeks for processing and shipping" disclaimer. Yet I sent this order to China electronically only 10 days ago. A week ago this physical package was in China, and now I'm holding printed circuit boards.
After removing the DHL shipping envelope, here's the box I received:
The boards come in this heavy plastic packaging. There isn't anything separating the boards from each other (there are five in this package), but the vacuum-sealed packaging keeps the boards from sliding against each other and potentially damaging the surfaces.
The empty space in the box was filled with bubble-wrap, so nothing was sliding around during shipping. So no real worries about damage in shipping, unless someone drops something heavy and pointed on it.
I also ordered a solder stencil. Some people may feel comfortable placing little blobs of solder on a board by hand, but I've tried that and it doesn't go well. The cost of the stencil ($7 plus some shipping) is well worth it to me.
The stencil came in this heavy zip-lock plastic bag to protect it from scratches. One of the tricks I've learned is to have the solder stencil cut down to roughly the size of the board so everything fits snugly in the box. That way you're not paying shipping for a box much larger than it needs to be.
And finally, here's one of the boards:
The one issue I have every time I order boards is realizing just how small the components that go onto it are. This board is 6.6" by 4.25", but looks a lot larger when I'm viewing the layout on a 30" monitor. When I'm holding the actual board I remember what fun it will be to place the 500-some components that will go onto it.
Hi Reece, how do you plan to place the transistors? By hand?
ReplyDeleteKlaus
Hi Klaus!
DeleteYes, I do all the component placement by hand using tweezers and a lighted magnifying lens. Soldering is done with a hot air system. I also have a Mantis stereo microscope I bought surplus for close inspection. As much as I whine about it, assembling the board is part of the fun of the project.
It's actually easier than it sounds. Once you've done work with 0402 components, these 0603 parts seem big. There are only a few components to work with: Two types of transistor (one is 3 pins and the other 4 pins, so they're easy to differentiate); two values of resistors; two values of VDD/GND bypass capacitors, and two connectors. The layout and the flexibility of the solder stencil will allow me to do this in stages: the decode logic on the right, the DRAM array on the left, and finally the connectors.
I expect it'll take about five hours over one or two days. I just have to schedule that time among my other activities.
Klaus, what size resistors did you use on your board? Did you have your fabricator do the assembly, or did you do it by hand?
DeleteHi Reece, I have 0603 resistors and all transistors are SOT-143 (plus some 0603 LEDs and some 0805 and 1206 capacitors). I soldered all by hand (with lots of solder flux), no stencil. So I could populate and test the PCB step by step, which was very important for depugging.
ReplyDeleteMeanwhile I have a second 4004 PCB that a company populated with pick-and-plache machine, looks very clean. But it didnt work from the beginning and it took me some time to find the "bad" transistors.
All the best
Klaus