PCB News - Multi-layer circuit board "via hole cover oil" and "via hole opening window" are silly and unclear

Multi-layer circuit board "via hole cover oil" and "via hole opening window" are silly and unclear

Regarding the "through-hole opening" and "through-hole cover oil" of PCB multilayer circuit boards(the usage distinction between PAD and VIA), many customers and design engineers often ask suppliers when purchasing circuit boards. Do I need to do "through hole opening" or "through hole cover oil". At this time, many customers will have questions. What does this mean? Which option should I make in my file? The description of this problem is as follows:

I often encounter such problems. The file design is not standard, and it is difficult to distinguish which is the pad of the PCB multi-layer circuit board and which is the use of via. Sometimes the conductive hole is processed by the attribute of the pad, and sometimes the key hole is also used by the attribute. To deal with it, the design of VIA attributes and PAD attributes is confusing, leading to wrong processing, which is also one of the problems that often appear complaints. For circuit board manufacturers, when processing CAM data, some film processing engineers will make mistakes because the customer’s design documents are not standardized. Occasionally, some engineers will help customers modify the documents and make the non-standard design right. My own experience to deal with engineering data, this 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, this can be a reference for design engineers, improve 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, pads are particularly prone to several problems:

1. Via in the conversion process, the design is not standard or the design engineer is not clear about the conversion gerber setting rules, which causes problems

When you send a gerber file, the PCB manufacturer cannot tell which are vias 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 is a film file, the factory has no way to check whether it is a conductive hole or a key hole, check whether the gerber file has a soldering layer, and open it if it has. If there is no window, cover it with oil.

2. Pad and via are mixed together, causing problems

When the PCB multi-layer circuit board file is pads or protel, it is sent to the PCB multi-layer circuit board manufacturer, and the via hole cover oil is required. Please pay attention, you should carefully check whether the plug-in hole (pad) is also useful via Yes, otherwise the plug-in hole will be painted with green oil, which will lead to the failure of welding. Dispute point: The plug-in hole must be sprayed with tin on it, why is it covered with oil? In the same situation, you still need to check the file first, whether it is a pad design or a via design.

When the PCB multi-layer circuit board file is sent to the factory when it is pads or protel, the order is required to be via hole cover oil, but many customers use pads (plug-in holes) to represent conductive holes, which leads to conductive holes opening 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 soldermasktop-the via underneath, which means that all vias are opened, and if not checked, the vias are covered with oil.

To sum up: pad is made by pad, its own attribute is plug-in hole; via has two options, if the original file is provided, then you can choose when placing an order, if you provide a gerber file, please check the PCB multi-layer circuit Whether the board gerber file meets your requirements!