PCB Tech - What are the problems with the copper clad laminate in the pcb multilayer board

1. To be able to track and find

It is impossible to manufacture any number of PCB multi-layer boards without encountering some problems, which is mainly attributed to the material of the PCB multi-layer copper clad laminate. When quality problems occur in the actual manufacturing process, it seems that it is often because the PCB multilayer board substrate material becomes the cause of the problem. Even a carefully written and practically implemented technical specification for PCB multilayer laminates does not specify the test items that must be carried out to determine whether the PCB multilayer laminate is the cause of the production process problems. Here are some of the most frequently encountered PCB multilayer laminate problems and how to confirm them.

Once you encounter the problem of PCB multilayer laminates, you should consider adding them to the PCB multilayer laminate specifications. Generally, if this technical specification is not fulfilled, it will cause continuous quality changes and consequently lead to product scrapping.

Generally, material problems caused by changes in the quality of PCB multilayer laminates occur in products manufactured by manufacturers using different batches of raw materials or using different pressing loads. Few users have enough records to be able to distinguish specific pressing loads or batches of materials at the processing site. As a result, it often happens that PCB multi-layer boards are continuously produced and installed with components, and warping is continuously generated in the solder tank, thus wasting a lot of labor and expensive components.

If the batch number of the material can be found immediately, the PCB multilayer laminate manufacturer can verify the batch number of the resin, the batch number of the copper foil, the curing cycle, etc. In other words, if the user cannot provide continuity with the quality control system of the PCB multilayer laminate manufacturer, this will cause the user himself to suffer long-term losses. The following introduces general issues related to substrate materials in the manufacturing process of PCB multilayer boards.

2. Surface problems

Symptoms: poor printing adhesion, poor plating adhesion, some parts cannot be etched away, and some parts cannot be soldered.

Available inspection method: usually used to form visible water lines on the surface of the board for visual inspection:

Possible cause: Because of the very dense and smooth surface caused by the release film, the uncoated surface is too bright. Usually on the uncoppered side of the laminate, the laminate manufacturer does not remove the release agent. The pinholes on the copper foil cause resin to flow out and accumulate on the surface of the copper foil. This usually occurs on copper foil that is thinner than the 3/4 ounce weight specification. The copper foil manufacturer coats the surface of the copper foil with excessive amounts of antioxidants. The laminate manufacturer changed the resin system, stripping thin, or brushing method.

There are many fingerprints or grease stains due to improper operation. Dip with engine oil during punching, blanking or drilling operations.

Possible solution: It is recommended that laminate manufacturers use fabric-like films or other release materials. Contact the laminate manufacturer and use mechanical or chemical elimination methods. Contact the laminate manufacturer to inspect each batch of copper foil that is unqualified; ask for the recommended solution for removing the resin. Ask the laminate manufacturer for the removal method. Changtong recommends using hydrochloric acid, followed by mechanical scrubbing to remove it. Before making any changes in laminate manufacturing, cooperate with the laminate manufacturer and specify the user's test items.

Education staff in all processes to wear gloves to hold copper clad laminates. Find out if the laminate is shipped with a suitable pad or packed in a bag, and the pad has a low sulfur content, and the packaging bag is free of dirt. Take care to ensure that no one is touching it when using a silicone-containing detergent Copper foil, degreasing treatment for all laminates before plating or pattern transfer process.