Sunday, December 1, 2013

Some Fundamental information of Printed Circuit Board (PCB) Board

Nowadays, printed circuit board is widely used in electric & electronic field. This article introduces the fundamental information of PCB in details, including the definition, Gerber file, NC drill file, solder mask, silk screen, as well as the PCB finishing before ordering a PCB. Hope this tutorial can help our customers to improve their PCB knowledge.

The definition of PCB
For standard PCB, it is the combination of bare board and components on it. While for bare board PCB, it is called printed wiring board. We usually call it PWB.

What is Gerber File?
The Gerber format is a file format used by printed circuit board (PCB) industry software to describe the images of a printed circuit board (Signal, ground, power, solder mask, silk screen, and drilling layout plan, etc.). The Gerber format is the de-facto industry standard for printed circuit board image transfer. The Gerber format specification can be freely downloaded.

What is NC drill file?
THE NC DRILL FILE can be opened by Notepad. The NC drill file should have Tooling Size, and X Y info of the holes. An NC drill example is below: T define the hole size, X Y define the hole location. NC drill file can also define the NPTH holes; the best way is to generate a separate NC drill for NPTH holes (Non-plated holes).

Solder mask and silk screen:
The green or white oil on PCB is called solder mask, which is functioned as dielectric protective layer, can protects copper traces and also can prevent components to be soldered at incorrect place. Solder mask comes in different media depending upon the demands of the application. The lowest-cost solder mask is epoxy liquid that is silk screened through the pattern onto the PCB. Other types are the liquid image able solder mask (LPSM) inks and dry film image able solder mask (DFSM). LPSM can be silk screened or sprayed on the PCB, exposed to the pattern and developed to provide openings in the pattern for parts to be soldered to the copper pads. DFSM is vacuum laminated on the PCB then exposed and developed. All three processes go through a thermal cure of some type after the pattern is defined.
On the dielectric layer, a layer of silk screen will be printed. Some words will be printed to show the position of those components. It is also called legend.

PCB finishing
PCB Surface Finishes vary in price, availability, shelf life, reliability and assembly processing. While each finish has its own benefits, in most cases, the process, product or environment will dictate the surface finish that is best suited for the application. It is recommended that the end-user, designer or assembler work closely with their PCB supplier to select the best finish for the specific product design.

If need any more information on PCB, you could check and source from this website: Wonderful PCB Technology Co., Ltd is a professional PCB manufacturer for many years and could try best to help!

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