PCB Technical - PCB copper clad laminate problem

1. To be able to track and find

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

Once you encounter PCB laminate problems, you should consider adding it to the PCB laminate material specification. 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 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 PCBs are continuously produced and mounted with components, and warps are 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 laminate manufacturer can verify the batch number of the resin, the batch number of the copper foil, and the curing cycle. In other words, if the user cannot provide continuity with the quality control system of the PCB laminate manufacturer, this will cause the user himself to suffer long-term losses. The following describes the general issues related to substrate materials in the PCB manufacturing process.

Circuit board

Second, the surface problem

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

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

Possible reasons: 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.

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

Possible solutions:

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. Before making any changes in laminate manufacturing, cooperate with the laminate manufacturer and specify the user's test items.

Educate all process personnel to wear gloves to handle PCB 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.