Tips for Designing, Milling and Assembling PCB's
Tips for Designing, Milling and Assembling PCB's
1. Use Sockets. Use Chip Sockets for IC Chips, and Female Header pins as sockets for processor boards like Arduino Nano.
This allows for being able to cleanly test the circuit after the soldering has been done, without the tests being affected by a component or chip being installed. It also allows you to "borrow" these chips and components for use in other projects. So if you are no longer using the device you can just remove the chips and components and save a few bucks. Also, if you happen to burn up a component somehow, sockets let you replace the component without having to unsolder it and then solder in a new component. Simply swap it out. So those are 3 important benefits of using sockets.
2. Use components like bridges to move traces underneath them. This is a very handy and helpful technique. Under chips, between resistor leads, capacitor leads, etc.
3. Stretch leads on components that have wires like capacitors and resistors to create bridges for traces to run underneath. Say you have a capacitor with 2 leads that are side by side with no space in between. You can stretch apart the 2 leads by deleting one of the drill holes of the capacitor, and then add a Jumper Wire component, and delete one of its drill holes, and then you can bridge the gap graphically on the screen, while moving the 2 drill holes further apart by one space. Then you can run a trace underneath the capacitor.
4. Use a 2nd layer PCB to create drops for power and ground as needed to distribute power and ground to everywhere that you need it. Also use the 2nd layer PCB to route traces to hard to get to spots. PCB Maker is designed to be able to make a 2nd Layer PCB easily, while being able to see the 1st layer, but somewhat faded into the background.
To make a 2nd layer PCB first click on the 1st layer PCB, then click on the "Tools" Menu, then click "Make a 2nd Layer PCB Board on top of the current image". The software will then make a picture file of your current PCB, and then paint a semi-transparent color that is that of a new pcb top side, so you see the image of the first layer, but the image is faded to the back so it does not interfere with your drawing of the 2nd layer of the pcb, yet you can see where the original pcb is, and where all the drill holes are for it, so it makes it easy to create a 2nd layer for the first layer, and be able to visually see how they are going to fit together. It works great. We think this feature works very well. If there are a lot of jumper wires needed, it is a lot better to create a 2nd layer pcb, and solder male and female headers to the 1st and 2nd layer pcbs so that they can connect together, than it is to solder a bunch of jumper wires. If you need say more than 6 or more jumper wires, it may be easier to just create a 2nd layer PCB, and let the 2 PCB boards connect like an Arduino shield, with male and female header pins.
5. Get a Solder Station Soldering Iron. They are safer on components and much less hassle to use.
6. Make sure to have a solder sucker to remove solder when needed.
7. Use Ready Made component modules that let you off-load circuit assembly from your PCB to the module. It is easier, cheaper, and faster to buy, than build. Use your PCB like a multi-component shield. Use female headers on your pcb to plug modules into, which alows you to test the solder points for shorts without interfering with testing for shorts as noted in #1 of this list.
8. Remember to add power switches, battery connectors, or other power connectors, etc., as needed. It is easy to forget about these things.
9. Always test your milled pcb boards for shorts before any assembly or soldering.
10. Use component modules that help with trace routing. Our best example of this is using a multiplexer module where all of the inputs or outputs are sequential, like 1,2,3,4,5,6, etc. It is logical and easy to use, and it is great for trace routings. And avoid chips like the CD4051 8 channel multiplexer chip that creats a routing nightmare. You will end up needing a lot of jumper wires or a 2nd layer pcb to handle all the trace routings. Modules are your friend. Modules off-load work to the maker of the module, and off of you, and that is a good thing. Buying is cheaper than making. And modules tend to work better than what you can make on your own. View your PCB as glue for modules and processor boards. Check out our Heavenly Remote IR Hub PCB to see the tracing nightmare that the CD4051 chip creates. This circuit should be redesigned using a multiplex module, to simplify our PCB, and reduce the amount of work we have to do.
11. Brush the back of your PCB's using a stiff brush, under running water, after milling to remove any copper fragments from the traces. So far, we have had no need for sanding. With a new scribe bit, we have had no real problems with burrs or shorts. Sometimes brushing might not clean out a track, but we then just use a header pin to clean out any copper fragments causing a short. But generally, we are not having a lot of those happen, although this is still a fairly new process. We have not had to sand a single PCB like before when we were milling with V-bits. We do not like sanding the copper backing because it looks less nice. We would sand it under running water with about a 1500 grit sand paper. We prefer not to sand the back, because it looks so much better unsanded. For us, brushing has been sufficent, with 1 or maybe 2 exceptions of having to clean out a trace manually with a header pin. Maybe if we did a better job of brushing it, we may not have had to do that.
12. Do not use CNC machine with an end mill to cut out the perimiter of the PCB. Instead, use a band saw. Much less time, much less dust, and your CNC machine stays clean. Use the "Do Not Generate GCode For End Mill" option on the right in GCode Settings to scratch mill a perimeter trace so you can have a good line for the band saw blade to follow.
13. Do not use CNC machine with an end mill to cut out the Screw holes. Instead, use a drill press, with successively larger drill bits. Much less time, and your CNC machine stays clean. Use the "Do Not Generate GCode For End Mill" option on the right. Same as in #12.
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