In the previous article, WorkingBear talked about how to improve the adhesion of PCA to resist the impact of stress. Today, We will move on to another topic: “How to increase the ability of components or circuit boards to resist stress?” Because the maximum impact of stress on solder cracking is board bending, we only need to think about how to enhance the product’s ability to resist the stress impact caused by board bending to solve the problem of solder cracking.
PCB is composed of layers of Copper Clad Laminate (CCL) and Prepreg (PP) stacked together. In modern PCB manufacturing, CCL has become a standard material. Each CCL manufacturer provides customers with product specifications that indicate the peel strength of the CCL. From these specifications, we can see that the peel strength is higher when using 1.0 oz copper foil thickness than when using 0.5 oz. Different models and manufacturers of CCL also have different peel strengths, so selecting the appropriate CCL specifications is necessary to enhance the bonding force between the copper foil and PCB substrate.
Below are recommendations for BGA pad design to enhance the soldering strength from Workingbear.
We had several pages talking about the relationship between solder cracking and bonding force. Workingbear personally doesn’t think that making design a change to the pad of PCB can help much with the ability of BGA soldering to resist stress, as it is like a drop in the bucket! A board’s bending or deformation can easily negate all your efforts in improving pad design and solderability. Workingbear still thinks that strengthening the mechanism design and improving the board’s ability to resist bending and deformation is the best solution to fix BGA solder cracking.
In the previous article, we talked about “How to Increase the bonding force for PCBA by using “Copper” base as the PCB surface finish“. Today, we will discuss further how the SMD (Solder Mask Defined) and NSMD (Non-Solder Mask Defined) pad designs of the BGA package affect the solderability and how these two types of pads affect the bonding force of PCA.
Increasing the solder contact area of a component terminal or leads will generally improve the solderability of the component, as it provides more surface area for the solder to wet and bond to the terminal. This can result in a stronger and more reliable solder joint.
Following last discussion, we learned that solder cracking is caused when the stress placed upon it exceeds the strength of the bonding force. However, it’s possible to address this issue by increasing the bonding force of the printed circuit board assembly (PCBA). By doing so, we can effectively eliminate solder cracking, making it a more reliable and robust technology for a wide range of applications.
