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It is impossible to manufacture any number of PCB polylaminates without encountering some problems, mainly due to the material of PCB polylaminates coated with copper laminates. When quality problems occur in the actual manufacturing process, it also seems that PCB multilayer substrate material is often the cause of the problem. Even a carefully written and executed technICal specification for PCB laminates does not specify the tests that must be carried out to determine that PCB laminates are the cause of manufacturing process problems. Listed here are some of the most commonly encountered PCB laminate problems and how to confirm them.
Once the PCB laminate problem is encountered, it should be considered to add to the PCB laminate material specification. Often, if this specification is not fleshed out, it will result in constant quality changes and consequent obsolescence.
Usually, material problems arising from quality variations in PCB laminates occur in products manufactured by manufacturers using different batches of materials or with different pressing loads. Few users maintain sufficient records to distinguish specific pressing loads or material batches at the processing site. As a result, PCB multilayers are constantly produced and loaded with components, and continuously warped in solder slots, thus wasting a lot of labor and expensive components.
If the loading lot number is immediately available, the printed circuit board laminate manufacturer can check the resin lot number, copper foil lot number, curing period, etc. That is, if the user does not provide continuity with the quality control system of the PCB laminate manufacturer, the user himself will suffer in the long run. The following introduces the general issues related to substrate materials in the manufacturing process of PCB multilayer board.
Two, surface problems
Signs: poor print adhesion, poor coating adhesion, some parts can not be etched off, and some parts can not solder.
Possible inspection methods: Usually used for visual inspection by forming visible streaks of water on the surface of the plate:
Possible cause: Because of the very dense and smooth surface caused by the release film, the surface of the uncovered copper is too bright. Usually on the uncopper-covered side of the laminate, the laminate manufacturer does not remove the release agent. Pinholes in the copper foil cause the resin to flow out and accumulate on the surface of the copper foil, which is usually found on thinner copper foil than the 3/4 oz weight specification. Copper foil makers apply excessive amounts of antioxidants to the surface of copper foil. The laminate maker changed the resin system, the stripper, or the scrub method.
There are many fingerprints or grease stains due to improper operation. Wet with oil during punching, blanking or drilling operations.
Possible solutions: Laminate makers are advised to use fabric - like films or other release materials. Contact the laminate manufacturer for mechanical or chEMIcal removal. Liaise with laminate manufacturer to inspect each batch of copper foil for non-conformity; Ask for a solution to remove the resin. Ask the laminate maker for removal methods. General recommended the use of hydrochloric acid, followed by mechanical brush removal. Cooperate with PCB laminate manufacturer and specify user test items before any changes are made to laminate manufacture.
Teach all process personnel to wear gloves to handle copper-clad plates. Make sure that the laminates are shipped with appropriate padding paper or bagged, that the padding paper is low in sulfur, that the packaging is free of dirt, that no one touches the copper foil while using detergent containing silicone, and that all laminates are degreased prior to plating or graphic transfer processes.