Punching is a relatively important process in PCB circuit board proofing, so what problems will arise in the PCB punching process?? Please follow the PCB engineer to find out.
—, section rough
1. Causes:
(1) The blanking gap between the concave and convex dies is too large; the cutting edge of the concave die is severely worn.
(2) The punching force of the punching machine is insufficient and unstable.
(3) The blanking performance of the sheet is poor.
2. Solution:
(1) Select the appropriate concave and convex punching gap.
(2) Trim the cutting edge of the die in time.
(3) Select the base material with better blanking performance and control the preheating temperature and time strictly according to the process requirements.
二. Holes and cracks between holes
1. Causes:
(1) The hole wall is too thin, and the radial extrusion force during punching exceeds the hole wall strength of the plate.
(2) The two adjacent holes are not punched out at the same time, and the hole punched back is squeezed because the hole wall is too thin.
2. Solution:
(1) The design of hole spacing should be reasonable, and the hole wall should not be smaller than the thickness of the substrate.
(2) The adjacent holes should be punched out at the same time with a pair of molds.
三, the shape is bulging
1. Causes:
The mold design is unreasonable; the concave mold of the shape blanking is deformed, and the long side is bulged.
2. Solution:
(1) When the overall size of the printed board is greater than 200mm, it is advisable to adopt the die punching shape of the upper and lower material structure.
(2) Increase the wall thickness of the die, or use materials with sufficient bending and tensile strength to make the die.
四, the waste jumps up
1. Causes:
(1) The adhesion between the copper foil and the substrate is poor, and the copper foil on the scrap is easy to fall off when punching, and enters the punched hole when the punch exits the die. (2) The gap between the die is too large, and the material leakage is not smooth. When the punch exits the die and unloads, the waste material will jump up.
(3) There is an inverted cone in the die hole, and the punching waste is difficult to fall, but jumps up when the punch exits the die.
2. Solution:
(1) Strengthen the incoming inspection of substrate materials.
(2) Reduce the gap between the concave and convex dies and expand the leakage hole.
(3) Trim the inverted cone of the die hole in time.
五. Waste clogging
1. Causes:
(1) The cutting edge of the die is too high and too much waste is accumulated.
(2) The concentricity between the leakage hole on the lower backing plate and the lower mold base and the die hole is poor, and the butt joint of the hole is like a step.
(3) The material leakage hole is too large, and the waste material is easy to accumulate irregularly in the hole; it is also easy to block when two adjacent material leakage holes are cut
inwardly.
2. Solution:
(1) Reduce the cutting edge of the die, and the number of waste accumulation can be reduced between 0.2mm.
(2) Adjust the vertical concentricity of the leakage hole on the die, the lower backing plate and the lower mold base, and expand the leakage hole on each part.
(3) When two adjacent leaking holes are inscribed, in order not to block the leaking material, it should be made into a round hole or a large hole.
