 We share our experiences making PCB's. Part IV - Ordering PCB's and what to expect
You've got the layout all done, and you have gerber files. Now it's time to get boards made! To get a quote, you'll need to tell the vendor what you want.
What specifications do you want?
- Board Material: This is the meaty part of the board: you want FR4.
- Finish Thickness: How thick the copper traces should be: .062" is most common. Thicker, wider traces can carry more current, at .062" thickness, a .01" wide trace carries about 300mA. A .025" trace will carry around 1A.
- Layer Count: A board with layers on both sides of the pcb is 2 sided. A board with layers only on one side is 1 sided.
- Tab-rout, Scoring, and Arrays: If your design is going to an assembler, you'll probably want to 'panelize' the design. Panelizing means you'll have multiple boards on a single, big pcb. Each board is usually separated by V scores. These scores allow you to separate each copy after assembly (like separating parts of a candy bar). Scoring is a small cut that you can do if your design is rectangular. Tab-rout is used if your design isn't rectangular, but it requires more space between each copy. Unless you're going to have your design assembled, you don't need to worry about this.
- Finish Plating: If the traces on your board are made out of copper, why do all the exposed bits of metal look silver? Copper oxidizes - making it hard to solder. Copper, when in contact with other metals, can also cause corrosion. The answer is to cover the exposed copper with another metal finish. Solder is fine (often called HASL for Hot Air Solder Level), but other materials are available.
There are a few other options that aren't very common: gold fingers, counterbore, etc. Unless you know you need this - you probably don't.
Ordering
There are many companies that will make PCB's for you. If you're using ExpressPCB or another vendor's application, you're probably tied to them, but if you can generate Gerbers, there are dozens of options for you. Here are some of the vendors I've used, and how to work with them;
PCB's come in a shrink-wrap pack
Gold Phoenix
Send them an email with your specifications and attach the gerber files. They charge about $120 for 155 sq. inches of boards, 2 layer. The lead time is 5 days, which is pretty good. I like Gold Phoenix for small runs or small boards - quality is good, and price is good. More details here.
Advanced Circuits
Use their online tool to generate a quote. Prices are competitive and they often have special price deals. Their barebones (no soldermask) service is good for prototyping, too. Because they're in the US, lead time and shipping time is very short. More details here.
E-TekNet
Use their online tool to generate a quote. Prices are competitive. I use them for mid-sized runs (300 boards or more). More details here.
ExpressPCB
They have a great deal on prototyping, but it's not so great for larger quantities. Quality is high, but you have to use their software (which doesn't create gerbers) for submitting your design. I think ExpressPCB is great when you're designing a project just for yourself, but not as great if it's something you want to post / sell on Gadget Gangster. More details here.
Once your order has been placed, the vendor will usually do a quick review of the board to make sure it can be manufactured. They're not going to check the advanced design characteristics, but they sometimes will catch mistakes. If it's good, it will get scheduled according to the lead time you've selected. Although it will sometimes be made earlier, I wouldn't count on it - expect it to take as long as they say (a 10 day lead time means 10 days). Once you get the boards in the mail, inspect them to make sure everything looks okay.
Stay tuned for Part V: Wrap Up!
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