Ordering PCBs from Manufacturers

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There are a great many companies around the world that can produce PCBs. This isn't an endorsement of any particular one of them -- it's basic information that you'll need to know to order PCBs using Gerber files. - dirknerkle

1. You need to know the dimensions of the board, preferably in mm but some accept inches. This may mean you'll have to use a Gerber viewer tool of some kind to load the Gerber files and either print the design on paper to measure it or perhaps the Gerber viewer displays dimension information. A good, free Gerber viewer is GERBV: https://sourceforge.net/projects/gerbv/
2. You'll need to know if it's a one or two-sided board. A one-sided board has copper on only one side while a two-sided board has copper on both sides. Very few (if any) DIY designs use more than two-sided copper boards.
3. You'll need to know the thickness of the board you want. A common, default thickness if 1.6 mm but you may have other options available when you order. Thinner boards are more flexible.
4. The default copper thickness is usually 1-ounce copper. Thicker (2-ounce, 3-ounce) is often available. The thicker the copper, the more current the board traces can carry. However, thicker copper requires hotter soldering temperatures and are sometimes harder for people to build. Generally speaking, designs that are designed for high-current loads would likely be more appropriate for thicker copper. Note also that thicker copper is more expensive for them to produce and since they're heavier, shipping costs usually rise, too.
5. You can order a special color for the solder mask/color of the board. The most common and default will probably be green. Some manufacturers don't charge extra for red, blue, white, yellow or black, and other colors may be available. Some may have an additional custom color charge. Sometimes the silkscreen color can also be specified but most of the time, the default will be white unless the board color is also white, and then the manufacturer will likely use black for the silkscreen printing.
6. Typically, a set of Gerber files contains 8 "layers" of information, and a set is usually encased inside a ZIP file for uploading to the manufacturer. In most cases, each of the 8 files should begin with the name of the board/design, followed by the file extension. The common file extensions for the 8 layers are:
  • boardname.GTL - this is the TOP copper layer
  • boardname.GBL - this is the BOTTOM copper layer
  • boardname.GTS - this is the TOP solder mask layer
  • boardname.GBS - this is the BOTTOM solder mask layer
  • boardname.GTO - this is the TOP silkscreen layer
  • boardname.GBO - this is the BOTTOM silkscreen layer
  • boardname.GML - this is the board outline/mechanical layer
  • boardname.TXT or .DRL - this is the DRILL layer, locations and sizes of drilled holes
There may be other questions such as "castellated holes," "number of different drill sizes," or "max/min hole size," etc. but if you don't know what the heck they're asking, just leave those boxes alone. The manufacturer will let you know if there's a problem with the Gerber files that you upload and in most cases, you won't have any issue.
The only thing left is the delivery time and cost. Depending on the quantity of boards ordered, weight can become an issue that requires a higher shipping fee. 2 or 3-day DHL, Fedex or UPS shipping is usually available at extra cost (typically about $20-$25) while normal, snail-mail delivery might be less than $10 and if you don't need them quickly, understand that snail-mail might take a month or more. If you plan to order several boards, do them together in the same order and then the DHL, Fedex or UPS faster shipping can be the best deal.
A question always comes up about "panelizing" boards. Panelizing is the process of having multiple PCBs made on the same PCB material but with some v-groove scoring lines between them so that you can "break" the boards apart. Each manufacturer may have their own methods for producing the boards in this way, in general, the board production cost is a factor of the total area required to product the PCBs.
A method I've found that works well (in most cases anyway...YMMV) is to check the manufacturer's default board size for manufacturing. This is usually right there on the order screen as the default. For example, if the default is 100mm x 100mm, then that size should be able to handle four boards that are 50mm or less on a side. Then I would order the 100x100 default size but would also request in a special note with the order that I wanted them to panelize the board using v-scoring between the individual boards. If the order was for 5 boards at the 100x100 default size (i.e. that's what you're paying for), it's likely that you'd actually receive 5 panels of 4 boards each for a total of 20 individual PCBs once you break them apart.
In any event, good luck. May the Schwartz be with you.