Once a printed circuit board has become warped, it is nearly impossible to fix. Thus, the best method for fixing PCB warping is by mitigating risks that cause it from the start through smart board design, as well as an understanding of the importance of thermal management in PCB manufacturing.

In this section, we address several of the methods printed circuit board fabricators and manufacturers employ to avoid or fix PCB warpage.

Designing Around Warpage

As PCB factory china knows that,the best way to avoid warpage is to design printed circuit boards with the potential for warpage in mind. As stated previously, all printed circuit boards will warp to some degree, but the amount to which they do is dependent on created balanced designs. A couple of ways to do this include:

Balancing layers of a multilayer printed circuit board so that layer thicknesses are symmetrical along the center of the printed circuit board.

Using the same supplier for prepregs and core sheets to ensure the coefficient of expansion is similar.

Matching the outermost layers on both sides of a printed circuit board to match each other. If they copper areas on both sides differ significantly, their thickness will be uneven, causing warp.

Pallets and Fixtures

One method PCB manufacturers have historically used is a pallet that clamps down the board during the manufacturing process. For those who have used watercolors, this method may be familiar. After applying watercolor paints to paper, the sides will generally curl up on themselves unless they are taped down. This logic applies to printed circuit boards in a superheated environment by pinning the corners down and preventing warpage from occurring through side clamping the vertical and horizontal planes.

Unfortunately, this method has limitations. This type of fixture slows down the PCB manufacturing process, adds additional costs, and reduces flexibility in a high mix environment.

Plate Flattening

Some PCB factory china have specialized machines for flattening out boards that deviate too far from the norm.