We recently ordered a MAX10 FPGA board and an e-paper control board from PCBWay. To our surprise, the board we ordered was manufactured the next day and was awaiting pickup.
How long does it take to get the PCB from PCBWay?
The PCB ordered from PCBWay on November 14 were manufactured the next day, November 15. It was picked up by DHL on the 16th and arrived at Narita the next day, the 17th. The package arrived three days later on the 20th.
So we received the PCB in hand in 7 days after placing the order.
This time it arrived in a PCBWay 6th anniversary box. It's great to receive the PCB within a week of placing an order.
Review the PCB
Let's take a look at the stencil and PCB that arrived.
When I ordered, I wrote in the notes section that the stencil should be cut to 15cm x 15cm, so the stencil was perfectly cut at 15cm. The corners are also cut round and very nice.
Let's look at the FPGA PCB. It is beautifully manufactured. Unfortunately, the serial number is printed in large letters on the main PCB instead of on the useless part. The serial number is under "kohacraft.com" in the photo.
The electronic paper control PCBs are also beautifully manufactured. Not pictured, but the serial number was printed on the discarded part of the PCB here. The silk printing is nicely printed without shifting.
Components mounting
The parts for the FPGA PCB haven't arrived yet, so I'd like to mount the components for the electronic paper control PCB.
Printing solder paste
Place a PCB of the same thickness around the target PCB.
Insert a thumbtack through the holes in the PCB and stencil. This allows the PCB and the stencil to be perfectly aligned. It's very convenient and I recommend it.
Put solder paste on the back of the stencil. The solder paste is TS391LT50 from CHIPQUIK. This is a convenient low-melting-point solder paste that can be stored at room temperature. The grain size is also finer than those made in China, so even stencils with narrower pitches, such as 0.4mm pitch, can be soldered out cleanly.
You can use your used credit or loyalty cards to print.
I was able to print the solder paste beautifully.
Mount components
I use an electric vacuum pick to mount the parts, not tweezers.
This is a system that uses air pressure to suck on top of the part, so the part will not fall off by mistake while moving, as is the case with tweezers. The components can be moved in a stable manner.
Also, when you use tweezers, the tips of the tweezers open up when you release the component, so you need space on both sides of the component to do that, but when you use a vacuum pick, you're sucking it up from the top, so you can implement it even if the components are crowded together.
If you want to mount smaller components, you will need a nozzle, which is sold separately.
However, if you use the tip of the nozzle to adjust the position of the component during mounting, you may accidentally stick the nozzle into the solder paste and the nozzle may become clogged. I use an inexpensive type so that I can be disposable in such cases. The inexpensive type retails in the kohacraft shop.
It took a long time to implement because of the number of components, but thanks to the electric vacuum pick, it was definitely faster than the tweezers.
Reflow
It reflows in a convection oven with hot air circulating through the oven. I use a Tescoom convection oven that allows me to change the temperature in detail while heating.
At the same time, use a thermocouple thermometer to reflow while adjusting the temperature so that the temperature profile of the solder paste is obtained.
I was able to reflow it nicely. This PCB has a 0.4mm pitch CPLD, connector, and QFP power supply IC, so I'm nervous to see if I'm able to mount them well.
Next time, I'd like to check the operation.
2020.10.27 Add: Continue reading
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