PCB deformation on the production of printed circuit boards is very large, warpage is also one of the important issues in the process of circuit board production, loaded with components of the board after welding bending, component feet is difficult to neatly. The board also can not be mounted to the chassis or machine socket, so the PCB deformation will affect the normal operation of the entire post-process PCBA process. So is there any way to prevent PCB deformation?
The impact of PCB deformation
PCB deformation, also known as warpage, has a great impact on the welding and use. In particular, communication products, single board installation using plug box installation, there is a standard spacing between the inserts, with the narrowing of the panel, the gap between components on adjacent inserts is getting smaller and smaller, if the PCB is bent, it will affect the plugging and unplugging, will touch the components. On the other hand, the deformation of the PCB has a great impact on the reliability of BGA-type components. Therefore, it is very important to control the deformation of PCB during and after the completion of welding.
PCB anti-deformation design requirements
The degree of PCB deformation is directly related to its size and thickness. General aspect ratio ≤ 2, width-thickness ratio ≤ 150.
Multi-layer rigid PCB is composed of copper foil, semi-cured sheet and core board. In order to reduce the deformation after press fit, the laminated structure of the PCB should meet the symmetry design requirements, that is, the thickness of the copper foil, media category and thickness, graphic distribution category (line layer, plane layer), press fit, etc. are symmetrical with respect to the centerline of the PCB thickness direction.
For large size PCB, should be designed to prevent deformation reinforcement or liner plate (also known as fireproof board) which is a mechanical reinforcement method.
for the local installation, PCB deformation is likely to cause structural components, such as CPU card holder, should be designed to prevent PCB deformation liner.