Question

What are the main causes of PCB blind hole breakage?

Answer 1

The main reasons for PCB blind hole damage are:

1. The bonding force between the blind hole copper and the bottom copper is poor, which leads to the separation of the blind hole copper and the bottom copper during the use of the product.

2. The copper at the foot of the blind hole is thin, causing the copper at the foot of the blind hole to break during use of the product.

Answer 2

High-density integration (HDI) technology in PCB manufacturing processes can enable end product designs to be more miniaturized while meeting higher standards of electronic performance and efficiency. HDI technology is currently widely used in mobile phones, digital cameras, notebook computers, automotive electronics and other digital products, among which mobile phones are the most widely used.

The use of laser blind vias as the main micro vias is one of the key technologies of HDI. The characteristics of laser blind holes with small aperture and large number of holes are an effective way to achieve high wiring density of HDI boards. Therefore, the reliability of laser blind holes directly determines the reliability of the product.
Judging from the existing research results in the industry, the reliability of laser blind holes mainly depends on the process flow and dielectric layer materials.
Generally speaking, the main causes of blind via failure include:
(1) Due to the poor bonding force between the blind hole copper and the bottom copper, the blind hole copper and the bottom copper appear to separate during use of the product;
(2) Since the copper of the blind hole foot hole is thin, the copper of the blind hole foot hole breaks during use of the product. This article uses an HDI product laser blind hole failure case with cracks at the bottom as the starting point to discuss the failure mechanism of poor bonding between the blind hole and the bottom copper.

Answer 3

Remaining glue at the bottom of the hole causes cracks at the bottom of the blind hole

During the preparation process, blind holes need to go through key processing processes such as laser drilling and plasma. The main function of laser drilling is to ablate the resin in the blind holes. However, during this process, the laser drilling energy may be insufficient or the resin may be damaged. Due to the back-deposition effect, there is a small amount of resin residue at the bottom of the blind hole. Insufficient treatment during the subsequent plasma glue removal or chemical glue removal process will result in excess glue on the base copper at the bottom of the blind hole, causing the blind hole to be separated from the inner copper layer. Insufficient bonding force between them.