Reasons for Copper Strip Falling off of Rogers High Frequency Microwave RF Board

The circuit board manufacturer, circuit board designer and PCBA manufacturer explain the three main reasons for the copper strip falling off of Rogers high-frequency microwave RF board

The copper wire of PCB Rogers high-frequency microwave RF board fell off (also known as copper throwing). PCB Rogers high-frequency microwave RF board factory said it was a laminate problem, and required its PCB Rogers high-frequency microwave RF board production factory to bear the bad loss. According to customer complaint handling experience, common reasons for copper rejection in PCB Rogers high-frequency microwave RF board factory are as follows:

1、 Process Factors of PCB Rogers High Frequency Microwave RF Board Factory

The copper foil is excessively etched. The electrolytic copper foil used in the market is generally single-sided galvanized (commonly known as ashing foil) and single-sided copper plated (commonly known as reddening foil). The common copper throwing is generally more than 70um galvanized copper foil, and the reddening foil and the ashing foil below 18um have basically no batch copper throwing.

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When PCB Rogers high-frequency microwave RF board has designed the etched line, if the copper foil specification changes but the etching parameters remain unchanged, the copper foil will stay in the etching solution for a long time. As zinc is a kind of active metal, when the copper wire on Rogers high-frequency microwave RF board of the wireless communication PCB is immersed in the etching solution for a long time, it will inevitably lead to excessive side erosion of the line, resulting in the complete reaction of the zinc layer on the back of some thin lines and separation from the substrate, that is, the copper wire falls off.

Another situation is that there is no problem with the etching parameters of PCB Rogers high-frequency microwave RF board, but after etching, the copper wire is also surrounded by the residual etching solution on the convenient surface of PCB Rogers high-frequency microwave RF board due to poor water washing and drying, and if it is not treated for a long time, it will also cause excessive side erosion of copper wire and copper throwing. This situation is generally manifested as concentrated on the thin line, or in wet weather, similar defects will appear on the whole PCB Rogers high-frequency microwave RF board. Peel off the copper wire to see that the color of its contact surface with the base layer (the so-called roughening surface) has changed, which is different from the color of the normal copper foil. What you see is the color of the original copper at the bottom layer, and the peeling strength of the copper foil at the thick line is also normal.

2. The design of Rogers high-frequency microwave RF board for wireless communication PCB is unreasonable. If the circuit is designed too thin with thick copper foil, it will also cause excessive etching of the circuit and copper throwing.

3. In the process of Rogers high-frequency microwave RF board of wireless communication PCB, local collision occurs, and the copper wire is separated from the base material by external mechanical force. This defect is characterized by poor positioning or orientation, and the detached copper wire will have obvious distortion, or scratches/impact marks in the same direction. Peel off the copper wire at the defective part and look at the rough surface of the copper foil. It can be seen that the color of the rough surface of the copper foil is normal, there is no side corrosion, and the peeling strength of the copper foil is normal.

2、 Reasons for laminate manufacturing process

Under normal circumstances, as long as the high temperature section of the laminate is hot pressed for more than 30min, the copper foil and the prepreg will be basically bonded, so the bonding will not affect the bonding force between the copper foil and the substrate in the laminate generally. However, in the process of laminating and stacking, if PP is polluted or the rough surface of the copper foil is damaged, the bonding force between the copper foil and the substrate after laminating will also be insufficient, resulting in positioning (only for large plates) or sporadic copper wire falling off. However, there will be no abnormality in the peeling strength of the copper foil near the measuring line.

3、 Reasons for raw materials of laminate

It is mentioned on the Rogers high-frequency microwave RF board of the wireless communication PCB that the common electrolytic copper foil is the product with the wool foil galvanized or copper plated. If the peak value is abnormal during the production of the wool foil, or the coating crystal branch is bad during the galvanizing/copper plating, resulting in the insufficient peeling strength of the copper foil itself. When the defective foil is made into the PCB Rogers high-frequency microwave RF board and is inserted in the electronics factory, the copper wire will fall off under the impact of external forces. Such poor copper throwing will not cause obvious side erosion after peeling off the copper wire to see the rough surface of the copper foil (i.e. the contact surface with the base material), but the peeling strength of the entire copper foil will be very poor.

2. The adaptability of Rogers high-frequency microwave RF board copper foil and resin for wireless communication PCB is poor: some laminates with special properties, such as HTg board, are used now. Because the resin system is different, the curing agent used is generally PN resin. The resin molecular chain structure is simple, and the degree of crosslinking during curing is low, so it is inevitable to use copper foil with special peak value to match it. When the copper foil is used in the production of the laminate, it does not match the resin system, resulting in insufficient peeling strength of the metal foil on the sheet, and poor copper wire falling off during the plug-in. PCB manufacturing, PCB design and PCBA processing manufacturers explain the three main reasons for the copper strip falling off of Rogers high-frequency microwave RF board.