PCB via hole opening window, cover oil, filled oil definition and comparison

PCB via hole opening window, cover oil, filled oil definition and comparison

First of all we have to understand a question, what is the via? Vias are also called metallized holes. In the double-sided and multi-layer boards, in order to connect the printed wires between the layers, a common hole, that is, a via hole, is drilled at the intersection of the wires that need to be connected on each layer.

1. Three methods and definitions of via processing

There are three ways to handle vias:

Via Window Via Cover Oil Via Plug Oil

1. Through-hole opening: It is the tin on the solder ring of the via (like the plug-in pad, which is exposed and sprayed with tin) to open the window and spray tin. It is generally used to debug the measurement signal. The disadvantage is that it is easy to cause a short circuit. .

2. Via cover oil: that is, the solder ring of the via hole (via) is covered with solder mask ink.

3. Via plug oil: refers to plugging the hole with ink in the hole

Second, the inspection standards of the three processing methods

1. The opening of the via hole is like a plug-in pad, and the window is opened and sprayed with tin. The inspection standard: tin can be applied, and tin can be applied easily.

2. Inspection standard for via cover oil: it is not easy to tin during patching.

3. Inspection standard for oil plugging in via holes: First of all, it must be opaque, and there must be ink coverage and blockage on it.

3. Comparison and distinction between via cover oil and via plug oil

The process of via plug oil is an important supplement to the via cover oil, so generally high-quality boards will require plug oil. And often many engineers who have just entered the industry are stupidly unclear. So how do you differentiate between the two?

The requirement of the via cover oil is that the ring ring of the via hole must be covered with ink. The emphasis is to ensure the thickness and coverage of the ink at the edge of the hole. The key control is that the ring ring does not accept false copper exposure and thin orifice oil.

Via plug oil is to make the plug hole with ink in the hole of the via hole, emphasizing the quality and compactness of the plug hole, and it cannot transmit light after plugging the hole.

The method of plugging the via hole is to first plug the entire via hole with ink to block the via hole, so that the ink on the solder mask ring will not flow into the via hole, so as to avoid the yellowing of the via hole (if Your requirements are relatively strict. If you place an order for hole cover oil, usually the cover oil is not full or yellowish, and you can change it to hole plug oil later). In addition, the smaller the via hole, the easier it is to plug, and the via hole of the fortress oil is not easy to be too large (for example, the plugging oil of the Jiewei circuit board is directly used for ink plugging, and it is even printed with a plug. It is recommended that the via hole that needs to be plugged is designed to be within 0.5mm. This is also free, no additional money is required).

Note: If it is a gerber file, it will be processed according to the file, and the selection is invalid. For example: the gerber file is designed to open the window, and the order is placed into the via cover oil. Most factories will communicate with the customer to confirm it. If the factory does not see that the file does not match the order, it will be produced according to the gerber file!