The three ends of the copper strip of PCB circuit board

PCB circuit board copper wire stripping (is also often said to throw copper) is not good, PCB factory is laminate problem, requiring its production factory to withstand losses. According to customer complaint handling experience, the common end of PCB factory copper dumping consists of the following LED panel PCB circuit board copper strip three ends do you know?

First, PCB factory manufacturing process factors

1. Copper foil corrosion is excessive, electrolytic copper foil used on the market is generally single-side galvanized (commonly known as gray foil) and single-side plated copper (commonly known as red foil), common copper is more than 70um galvanized copper foil, red foil and 18um below the gray foil basically have not been exposed to the bulk of the copper.

Customer's circuit board preset is better than the moment of etching line, if the copper foil specifications change and the etching parameters remain unchanged, resulting in copper foil in the etching liquid for a long time. Because zinc is a very active metal, when the copper wire on the LED advertising screen PCB for a long time in the corrosion liquid bubble in water, will cause excessive side erosion of the line, resulting in some fine line backing zinc layer was absolutely echo off and get rid of the substrate, that is, copper wire stripping.

There is also a situation that PCB etching reference is no problem, but after etching washing, and baking is not good, resulting in copper wire is also in PCB surface left by etching liquid surrounded, a long time has not been disposed of, will also be copper wire side corrosion excessive and throw copper. This kind of situation is generally expressed as concentrated on the fine line, or weather wet for a period of time, the whole PCB will be shown to be roughly similar to the bad, peel the copper wire to see that the contact surface with the base (that is, the coarse surface) color has changed, and the color is different from the normal copper foil, see is the bottom of the original copper color, thick line copper foil shedding strength is normal.

2. Part of the PCB process of the LED advertising screen collided, and the copper wire got rid of the substrate by external mechanical force. This is not good expression for bad positioning or orientation, stripping copper wire will have surface distortion, or scratches/impact marks in the same direction. Peeling the copper wire is not good to see the copper foil surface, you can see that the color of the copper foil surface is normal, there will be no side erosion is bad, and the copper foil shedding strength is normal.

3.LED advertising screen PCB circuit preset is not reasonable, with thick copper foil preset very careful line, will also lead to excessive line corrosion and copper.

Two, laminate circuit board process end

Under normal conditions, as long as the hot pressing high temperature section of laminate more than 30 minutes, copper foil and semi-cured sheet on the basic joint absolutely, so pressing ordinary will not affect the bonding force of copper foil and substrate laminate. However, in the process of laminate stacking and stacking, if PP pollution, or copper foil surface damage, will also cause laminate copper foil and substrate bonding force is not sufficient, leading to positioning (only for the large plate) or sporadic copper wire stripping, but the measurement line near the copper foil shedding strength will not be abnormal.

Three, laminate circuit board raw material end

1. It is mentioned on the LED advertising screen that ordinary electrolytic copper foil is galvanized or coppered products. If the peak value of the wool foil is abnormal when it is produced, or the galvanized/coppered, the coating crystal dendritic is not good, which leads to the falling strength of the copper foil itself is not enough, which is bad for the foil to curb the external impact of the copper wire when the printed circuit board is made into an electronics factory plug-in. This kind of copper is not good to strip the copper wire to see copper foil surface (that is, contact surface with the substrate) after the surface of the side corrosion, but the whole surface of the copper foil shedding strength will be very poor.

2.LED advertising screen copper foil and natural resin suitability is not good: some special properties of laminate used today, such as HTg plate, because of the whole system of natural resin is different, the curing agent is generally PN natural resin, natural resin molecular chain structure is simple, low degree of crosslinking when curing, it is necessary to use special peak copper foil match with it. When the production of laminate, the use of copper foil and the natural resin of the overall system is not matched, resulting in sheet metal foil shedding strength is not enough, plug-in will also reveal that the copper wire stripping is not good.