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What is the use of opening windows in PCB design? How to design?

May 06, 2021


I often hear people talking about opening windows in PCB design. What is window opening, what is the use of PCB design window opening, and how to open window? Next, I will answer for you.

What is window opening?

Usually, the leads on the PCB are covered with oil to prevent short circuits and damage to the equipment. The so-called window is to remove the paint layer on the wire so that the wire can be exposed to tin.

What is the use of opening windows in PCB design?

PCB design can not only realize the PCB as a plug-and-play plug-in, but also increase the thickness of the solder to achieve the purpose of excessive current.


As shown in the figure above, the window opens. It is not uncommon for PCBs to open windows, and the most common one may be a memory stick. Anyone who takes apart the computer knows that there is a golden finger on the memory stick, as shown in the figure below:

Here, cheat is the open window, plug and play.

There is also a very common function of window opening, that is, the later iron increases the thickness of the copper foil, which facilitates excessive current, which is more common on the power supply board and the motor control board.

How to open windows in PCB design?

In PCB design, threading and windowing can be set on the TOP/BOTTOM SOLDER layer.

TOP/BOTTOM SOLDER (top/bottom solder resist green oil layer): The top/bottom solder resist green oil is applied to prevent tin on the copper foil and maintain insulation.

Solder mask green oil opening windows can be set on this layer to the pads, vias and non-electrical traces of this layer.

1. In the PCB design, the solder pad will be opened by default (OVERRIDE: 0.1016mm), that is, the solder pad exposes the copper foil and expands by 0.1016mm, and solder is applied during the wave soldering process. It is recommended not to make any design changes to ensure weldability;

2. In the PCB design, the via hole will open a window by default (OVERRIDE: 0.1016mm), that is, the via hole has exposed copper foil, expanded by 0.1016mm, and has wave soldering tin. If the design is to prevent SOLDER from pasting on SOLDER MASK, you must select the PENTING option of SOLDER MASK to close SOLDER MASK.

3. In addition, non-electrical wiring can also be carried out separately in this layer, so that the green oil can be blocked and the windows can be opened accordingly. If it is on a copper foil wire, it is used to enhance the ability of the wire to overcurrent. Tin is added during the soldering process. If you use non-copper wire, usually used for logo and special character screen printing, you can omit it to create a character screen layer.