Technology | How to avoid the warp and twist of printed circuit board ?
One of the causes of the printed circuit board warping is that the substrate (CCL) may be warped,
but during the processing of the printed circuit board,the thermal stress, chemical influence, and improper production process may also cause
the warp and twist of printed circuit board. Therefore, for printed circuit board manufacturers, the first is to prevent the printed circuit board from warping during
processing;and secondly, there should be a suitable and effective treatment method for PCB boards that have already appeared warp and twist
First, prevent printed circuit boards from warping during processing
1) Prevent the PCB base material from being warped due to improper inventory
Since the moisture absorption of copper clad laminate (CCL) will increase the warping during storage, the moisture absorption area of single-side copper clad plate is very
large,and the warpage of single-sided copper clad plate will increase significantly,Minimize the humidity of the warehouse and avoid the bare copper plate to avoid the
warpage of the CCL in storage
2) Avoid warping due to improper design of printed circuit board circuitry or improper processing
For example, the PCB conductive circuit pattern is unbalanced or the PCB board is obviously asymmetrical on both sides,On one side, there is a large area of copper skin,
which forms a large stress, causing the PCB board to warp.High processing temperature or large thermal shock in PCB manufacturing process will also cause warping
3) Eliminate substrate stress and reduce PCB warpage during processing
Since the substrate is subjected to heat many times during the processing of the PCB and is subjected to various chemicals.
For example, after the substrate is etched, it should be washed, dried, and heated. When the pattern is electroplated, the plating is hot
all these processes of PCB manufacturing will cause the warp and twist of printed circuit board too
Second Method of printed circuit board leveling or flating
1. Flatten the warped plate in time in the PCB process
In the PCB process, the plate with a relatively large warpage is picked out and leveled by a roll-type leveling machine, and then put into the next process.
2 PCB finished board leveling method
For the completed, the warpage is obviously out of tolerance, and the PCB can not be leveled by the roll-type leveling machine.
For PCB boards with small warpage deformation, the PCB board to be leveled can be placed in an oven that has been heated to a certain temperature (temperature setting
can refer to the glass transition temperature of the substrate and the substrate is baked in the oven for a certain period of time) Observe the softening condition to
determine. Generally, the baking temperature of the fiberglass cloth substrate is higher, the baking temperature of the paper substrate can be lower; the baking temperature
of the thick plate can be slightly higher, and the baking temperature of the thin plate can be slightly lower. Some; the baking temperature of the PCB board that has been
sprayed with pine perfume should not be too high.) Bake for a certain time