PCB Tech - What are the ways to process PCB shape?

What are the ways to process PCB shape?

PCB blanking, hole and shape processing can all adopt die punching method. For simple PCB or PCB with low requirements, punching method can be used. It is suitable for the production of low-level and high-volume PCBs with low requirements and PCBs with low profile requirements, and its cost is low.

Punching: The single-sided paper substrate and the double-sided non-metalized epoxy glass cloth substrate with large production batches, many types and numbers of holes and complex shapes are usually punched with one or more molds.

Shape processing: PCB production of large batches of single-sided and double-sided shapes, usually using die punching. According to the size of PCB, it can be divided into upper blanking die and falling material die.

Composite processing: PCB hole and hole, hole and shape require high precision. At the same time, in order to shorten the manufacturing cycle and improve productivity, a composite mold is used to process the hole and shape of the single panel at the same time.

The key to processing PCB with molds is the design and processing of molds, which require professional technical knowledge. In addition, mold installation and debugging are also very important. At present, most of the molds of PCB manufacturing plants are processed by outside factories.

Precautions for mold installation:

1. Select the punch (including type, tonnage) according to the punching force calculated by the mold design, the size of the mold, the closing height, etc.

2. Start the punch, and check whether the clutch, brake, slider and other parts are normal, whether the operating mechanism is reliable, and there is no continuous punching phenomenon.

3. The shim under the die is usually 2 pieces, which must be ground on the grinder at the same time to ensure that the die is installed parallel and vertical. The leap position of the shim does not hinder the blanking and at the same time, it should be as close as possible to the center of the mold.

4. Several sets of pressure plates and T-head pressure plate screws should be prepared for corresponding use with the mold. The front end of the pressure plate cannot touch the straight wall of the lower mold. Emery cloth should be placed between the contact surfaces, and the screws must be tightened.

5. When installing the mold, pay great attention to the screws and nuts on the lower mold not to touch the upper mold (the upper mold is lowered and closed).

6. When adjusting the mold, use manual as much as possible instead of maneuvering.

7. In order to improve the punching performance of the substrate, the paper substrate should be preheated. The temperature is preferably 70-90°C.

The PCB hole and shape are punched by the die, and the quality defects are as follows:

Protruding around the hole or warping or delamination of copper foil; cracks between the hole and the hole; the position of the hole is not vertical or the hole itself is not vertical; the burr is large; the section is rough; the punched PCB warps in the shape of the bottom of the pot; ; Waste blockage.

The inspection and analysis steps are as follows:

Check whether the punching force and rigidity of the punch are sufficient; whether the mold design is reasonable and whether the rigidity is sufficient; whether the processing accuracy of the convex and concave molds, guide posts and guide sleeves is reached, and whether the installation is concentric and vertical. Whether the fit clearance is uniform. If the gap between convex and concave is too small or too large, it will produce quality defects, which is the most important problem in mold design, processing, debugging and use. The edges of convex and concave molds are not allowed to be rounded or chamfered. The punch is not allowed to have taper, especially when punching, whether it is a positive cone or an inverted cone. During production, pay attention to whether the cutting edges of convex and concave molds are worn. Whether the discharge port is reasonable and the resistance is small. Whether the pushing plate and the punching rod are reasonable and the force is sufficient. The thickness of the sheet to be punched and the bonding force of the substrate, the amount of glue, the bonding force with the copper foil, preheating humidity and time are also factors to be considered in the analysis of punching quality defects.