It is impossible to manufacture any number of printed circuit boards without encountering some problems, some of which are due to the information on the copper clad laminates. When presenting quality problems in the practice of manufacturing, it is often because of the substrate information. Even a carefully written and implemented technical standard for laminates, there are no rules to affirm that laminates are a test item that must be stopped for reasons that cause problems in the consumer process. Here are some of the most commonly encountered laminate problems and how to confirm them. Once you encounter problems with laminates, you should think about adding them to the standards for laminated materials. Generally, if we do not stop the enrichment work of this technical standard, it will form qualitative changes from time to time, and then lead to product scrapping.
Usually, the data problem caused by the quality change of the laminate is caused by different batches of raw materials used by manufacturers or products manufactured with different pressing loads. Few users can hold a large number of sufficient records, so that they can identify a specific pressing load or data batch at the processing site. Therefore, a situation often occurs: the printed circuit board is consumed and mounted with components from time to time, and the warpage is continuously generated in the solder bath, thereby consuming a lot of labor and expensive components. If the batch number of the charge is immediately available, the laminate manufacturer can check 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 laminate manufacturer, the user will suffer long-term losses. The following introduces the common problems related to substrate information in the manufacturing process of printed circuit boards.
1. Appearance problems signs of present meaning:
Poor adhesion of printing materials, poor adhesion of plating, some parts cannot be etched away, and some parts cannot be soldered Available inspection methods: usually use water to form visible water marks on the surface of the board to stop visual inspection, or use ultraviolet lamp reflection inspection, and use copper foil to reflect the presence of resin on the copper foil.
Possible reasons:
1. Due to the very dense and lubricious appearance formed by the release film, the uncoated surface is too bright.
2. Usually on the uncoated side of the laminate, the laminate manufacturer did not remove the release agent.
3. The pinholes on the copper foil form resin outflow and accumulate on the surface of the copper foil, which usually appears on copper foil thinner than the 3/4 ounce weight specification, or environmental problems have formed resin powder on the copper foil surface After lamination.
4. Copper foil manufacturers apply excess antioxidant to the surface of copper foil.5. The manufacturer of the laminate has changed the resin system, the release sheet, or the brushing method.
6. Due to improper operation, there are many fingerprints or grease.7. In the process of punching, unloading or drilling, it is contaminated with organic materials when it is stained with engine oil or other means.
Treatment methods:
1. It is recommended that laminate manufacturers use fabric-like films or other release materials.
2. Contact the manufacturer of the laminate and use mechanical or chemical methods to eliminate it.
3. Contact the laminate manufacturer to inspect each batch of unqualified copper foil; discuss the recommended treatment method for removing the resin to improve the manufacturing environment.4. Discuss the method of removal from the laminate manufacturer. Changtong recommends the use of hydrochloric acid, followed by mechanical removal.
5. Before stopping any changes in the manufacture of laminates, cooperate with the laminate manufacturer and rule the user's experimental projects
6. Personnel who educate all processes wear gloves to handle copper clad plates. Make sure that the laminate has suitable padding or packed in the bag during transportation, and the padding has a low sulfur content, and the packaging bag is free of dirt. Be careful to ensure that no one is using a detergent containing silicone Contact with copper foil to ensure that the equipment is in good condition.7. Degrease all laminates before plating or graphic transfer process.
2. Appearance issues
Significance: Significantly different colors of the laminate, different colors of the exterior, stains on the exterior or inner layer, and thin layers of various colors on the exterior of the laminate. Available inspection methods: visual inspection.
Possible reasons:
1. The glass cloth-based laminate has white cloth patterns or white spots on the surface before processing or after etching.
2. After processing, white spots appear on the surface or glass cloth is more exposed.
3. After processing, especially after soldering, there is a thin white film on the surface, which indicates that the resin is slightly etched or there are foreign deposits.
4. The color change of the substrate exceeds the appearance request that it may bear.
5. Due to the overheating of the laminate or the excessive immersion of certain potions for too long, the appearance of the substrate will produce brown or brown markings.
Treatment methods:
1. In very rare circumstances, it is due to the lack of resin on the surface, revealing the glass cloth, which is rare today. More often seen are tiny bubbles or small white voids on the surface. This is due to the coating of the glass cloth surface and the response of the resin system. It is revealed that a lot of glass cloth board, when the humidity increases, the surface resistivity drops. But boards with tiny bubbles or small bubbles usually don't land. Strictly speaking, this is just a matter of appearance. Dealing with laminate manufacturers to prevent such problems from happening again; and surely the internal specifications of tiny blisters can bear.
2. After processing, it is revealed that the most part of the glass cloth is due to solvent etching, and some surface resin is removed. Check all solvents and plating solutions with the laminate manufacturer, especially the time and temperature of the laminate in each solution to ensure that they are suitable for the laminate used. When possible, process according to the conditions recommended by the manufacturer of the laminate.
3. Check with the laminate manufacturer to ensure that the flux used is suitable for the board used. Investigate the process that may deposit minerals or inorganics. In the process that may deposit minerals or inorganics, use the water with minerals removed as much as possible under the circumstances.
4. Contact the laminate manufacturer to ensure that any major components or resins of the laminate (which have an effect on the color) are approved by the user before making changes. Sometimes excessive copper alloy transfer affects color. Dealing with laminate manufacturers, the range of looks that can definitely be tolerated.
5. Check the dip soldering operation, the solder temperature and the down time in the solder bath. Also check the ambient temperature of the heating element on the printed board or the entire printed board. Assuming that the latter exceeds the upper limit of the allowable temperature of the laminate used, the substrate will produce brown. The boards soaked by the concentration of certain potions for too long and too long will only appear when the test board is heated by the post-process. Check and control the concentration and time of the potion.
