PCB News - the difference between PCB via hole cover oil and via hole opening window

Many friends and design engineers often ask what is meant by "via opening window" and "via cover oil" when placing an order. How should I specify it? Here I will talk about it in detail. In fact, it is PAD and The usage of VIA is distinguished.

I often encounter such problems. The file design is not standard, and it is difficult to distinguish which is the pad of the printed circuit board and which is the use of via. Sometimes the conductive hole is processed by the attribute of the pad, and sometimes the keyhole is processed by the attribute of the via., VIA attribute and PAD attribute design is confusing, leading to wrong processing, which is also one of the problems that often appear complaints.

As for the circuit board production plant, when processing CAM data, some film processing engineers, because the customer's design documents are not standardized, they will make mistakes; occasionally some engineers will help customers modify the documents and make the non-standard design right. The experience of dealing with engineering data has led to and contributed to the non-standard design of customers.

Hereby explain: The last time you did the right thing, it does not mean that the file is right! All engineers must pay attention to the design standards and specifications. All the film processing engineers are requested to maintain the current status of the customer's documents as much as possible, and deal with them according to the design specifications and standards as much as possible, and not according to experience. Reflect the problem, so that you can be a reference for design engineers, improve the design quality and reduce the occurrence of problems!

This article mainly explains the connection between conductive holes, keyholes, and protel/pads/ and geber files. Conductive holes, via keyholes, 3 problems that are particularly prone to pads:

1. During the via conversion process, problems occurred due to non-standard design or the design engineer's unclear setting rules for the conversion gerber.

When you send a gerber file, the manufacturer cannot tell which are via holes and which are keyholes. The only thing that can be identified is to process according to the file. Where there is a soldering layer, there is a window. Dispute point: I want the via hole cap oil, and now the window is opened, which may cause a short circuit. When this kind of problem occurs, you need to check the file, because the gerber file is a film file, the factory has no way to check whether it is a conductive hole or a key hole, and check whether the gerber file has a solder mask, if so Open the window, if not, cover it with oil.

2, pad and via are mixed together, causing problems.

When the file is pads or protel, it is sent to the circuit board factory, and the via hole is required to be oiled. Please pay attention, you must carefully check whether the plug-in hole (pad) is also used by the via, otherwise the plug-in hole will also be on Green oil, resulting in failure to weld. Dispute point: The plug-in hole must be sprayed with tin on it. How do you cover it? In the same situation, you still need to check the file first, whether it is a pad design or a via design.

When the file is pads or protel, it is sent to the factory, and the order is required to be through-hole cover oil, but many customers use pads (plug-in holes) to represent conductive holes, which causes the conductive holes to open windows. Maybe what you want is via cover oil. At that time, the point of dispute may be: what I want is conductive via cover oil. Why did you open the window? At this time, you still need to check whether the file design is standard.

For this point, it is hereby stated that if it is via, it will be processed as via, and if it is a pad, it will be processed as pad. Because no one knows which is the conductive hole, which is the plug-in hole, and via and pad are the only identifiers, please know.

3. How to design via hole cover oil in protel or pads

There is a tenting option in the via attribute in Protel. If you check it, it must be covered with oil, then the transferred gbrber files are all covered with oil; in pads, the transfer of pads to files is to cover through holes (via). Oil method: When outputting the soldermask, which is the solder mask, just check the solder mask top-the via below, which means all vias are opened, and if not checked, the vias are covered with oil.