Or how to get a developed board without getting up because of the computer and without using chemicals, iron or ultraviolet.

How to get your board designed without getting up from behind the computer, using only the mouse and keyboard. Get paid without chemicals, solutions, irons, UV lamps, films, and noxious fumes - isn't that great?
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Many novice radio amateurs do not order boards at the factory, but make them at home. If the task is to make one single board, then this decision is justified, and if you need to make 5, 10, 20 boards? Or you can not do the etching process due to the fact that your second half does not allow you to arrange a miniature lab at home? Or was someone interested in your board / device, and you want to sell it? - in fact, the board made at the factory with mask and silk-screen printing looks much more beautiful and more solid.

In this post I would like to tell you how to order a board at the factory, what you should pay attention to and give some recommendations for the development of a printed circuit board.


Step-by-step instruction with comments

First thing

First of all, you need to decide on the plant that will produce your printed circuit boards, and learn the technological standards of the manufacturer.

Common parameters

In order to properly prepare the boards, you need to know the minimum thickness of the conductor / gap, the minimum and maximum values ​​of the diameter of the vias, the minimum size of the contact pad of the metallized hole, the distance from the edge of the board to the elements. In theory, this is the minimum you need to know in order to properly dilute a printed circuit board. This list only sounds so frightening, in fact, more than half of this you will remember after the first divorced board.

PCB categories

Laminated materials from which printed circuit boards are made are designated with FR (flame resistant) indexes. FR-1 is the worst, FR-5 is the best.
FR-1, FR-2, FR-3 is a paper impregnated with special solutions; FR-1 category boards are highly hygroscopic , so never use the FR-1 category PCB.
FR-4, FR-5 - fiberglass with epoxy composition.
FR-4 is often used in the manufacture of industrial equipment, while FR-2 is used in the manufacture of household appliances. These two categories are industry standardized, the FR-2 and FR-4 boards are suitable for most applications. If you are not chasing the ultra-low price, I recommend using FR-4.

Copper Foil Thickness

I would like to pay special attention to the thickness of the copper foil, all of the above parameters directly depend on this parameter. Standard thicknesses are 18 and 35 microns.
18 μm is used for digital electronics, in which there are no large currents, and there are high requirements for the minimum thickness of the tracks, and 35 μm are used in the boards, on the tracks (tires) of which a large current flows, and the cross section, that is, the width of the track (tires ). As an example: high-power audio amplifiers, 220-volt switching circuits with a decent current (5 or 10 A, where, due to the required clearance, it is difficult to make a wide, with a large cross-section, conductive bus)
At the same time, on the board with a thickness of 35 microns, small digital elements can be easily located - microcontrollers, FPGAs, and so on.
For 35 microns, the minimum clearance / width of the track - 0.24 mm - is not very large, but for 18 microns the minimum clearance / width of the track is 0.1 mm.
Non-standard thickness - 70 microns and / or 105 (100) microns - is used on purely power boards. Due to the 0.31mm gap, you will not be able to place many surface microcircuits, for example, atmega in a QFT package, but you can easily place output elements on such a board. And with the same current on the board with 105 microns, the width of the track will be 3 times less than on the board of 35 microns.
The basic rule, which I would recommend to use, take the maximum allowable thickness. But don’t donate components, I always order 35 microns because of the use of surface chips.

General recommendations

The layout of any board begins with determining the overall dimensions of the board - they are determined by the housing, or mount, or “free space” in which your board will stand.

Use land and power landfills; the more landfill, the better, if possible and necessary, separate analogue and digital landfills. If you plan that your board sometime, under any circumstances, can be assembled not manually, but automatically, then use not solid polygons, but mesh ones, use solid ones only for shielding certain places on the board.


For printed circuit boards with more than four layers, there is a general rule to place high-speed signal conductors between the ground and power polygons, and low-frequency conductors for external layers. Sometimes audio lovers make two polygons of the earth on both sides of the board for screening, if the issue of price is not worth it, then this is quite a reasonable step.

Try as far as possible to place the measuring and power elements, try to shield the measuring elements. An example of the power elements that are the main sources of electrical and magnetic noise are interrupters, transformers, motors, thyristors, triacs, relays, etc.

Make mockups, experiment - try to simulate all difficult moments on a computer_or collect on development boards, a proven solution is a reliable solution.

Make 3D versions of your boards, many modern editors allow it, it will help you to imagine how your product will look before it is assembled, and so, you can check whether your board with components is placed in your chosen case.

Your payment is ready, it's time to send

Any manufacturer has its own requirements for the data format in which you send them files. Many plants that specialize in pilot batches (the batch before the start of production is produced in small quantities to verify the wiring, testing, certification and demonstrations, in our case just for work), began to accept fees in the development project files. But this is still a rarity, and giving your project entirely to someone on the side is risky, for this reason I recommend giving the files and the drill file to the Gerber factory.
For convenience, I recommend the program CAM350, which combines the files, and the output you have is not a whole folder with a bunch of files, but only 1 file with all layers and drilling.

Sending fee

The next step is to fill in the order form and / or to write an explanatory note to your board, where you must specify the material, material thickness, foil thickness, number of layers, mask, silk-screen printing, board file name.
In many factories, the order form is typical, for example, “Resonit”. You also need to specify the method of receiving payment. You can send it by mail, and maybe a courier to the house. For example, at “Rezonit” the boards are made within 3 days, after 1-2 days they are in St. Petersburg and on this or next day they are at your place, for a total of 5-6 days. At the weekend ordered - the next weekend received.

Bill payment

Most factories issue invoices that can be paid at a savings bank. Some, like the above-mentioned "Resonit", made the possibility of payment via the Internet, there are options for payment through a bank card or Yandex money.

Mini Bonus

When ordering urgent production, the plant makes a small number of boards. Sometimes on a sheet of PCB that uses the plant. There is still room for your board, and other boards are placed there, for example, by ordering 10 boards, you can get 12 - additional 2 for free, but I would like to clarify that this does not always happen and you should not count on it.

Ps

I want to apologize in advance if the article contains errors or inaccuracies. Write to me personally, I will try to fix everything as quickly as possible.

Update: Found useful material for novice developers - Developer’s Reference Manual