Another Breakthrough in HDI Technology in PCBMay – 7-step HDI Board Developed Sucessfully

PCBMay is a high-end quick PCB and assembly prototypes R&D and manufacturing enterprise.

It is technology-oriented and highly focuses on HDI boardshigh frequency & high speed, and special process PCB circuit boards.

Based on the stable production of 1-6 steps HDI boards in the past few years, the technology center once again overcame difficulties, carefully planned, and successfully developed a 16-layer 7-step interconnect HDI board (Any layer HDI) at one time.

Overview of HDI Board

Regarding any layer HDI technology, Apple company has used HDI Any layer interconnection technology from iPhone 4 to iPhone 12.

Since 2018, the leading domestic mobile phones Huawei, OPPO, VIVO, and Xiaomi flagship phones are equipped with HDI Any layer interconnection technology.

In 2019 In the domestic market, Huawei has launched the P30 Pro 5G version, VIVO iQOO 5G version, and OPPO Reno 5G version, all adopting any layer of interconnection HDI structure.

Judging from the current development stage, with the upgrading of 5G mobile phone function modules and the increase in signal transmission requirements, the integration of internal space and the number of components will continue to increase, which will endlessly force the upgrade of mobile phone motherboards.

PCBMay estimates that ordinary 5G mobile phones in the future will require at least 8-12 layers 4-step HDI motherboards, and the high-end flagship phone will be directly upgraded to 14-layer 5-step or higher HDI (Any layer-HDI) level. Currently, The technology of PCBMay has surpassed most of the current domestic enterprises.

Introduction of HDI Key Process Technology

HDI Any layer interconnection is a high-density connection technology, which has a high technical threshold.

The main processing difficulties: interlayer alignment, laser drilling, hole filling plating, complicated circuit processing, etc.

At present, few domestic manufacturers have high process capability and fast delivery capability.

PCBMay is close to the market. Based on the urgent needs of customers for high-level and high-end any layer-HDI bare boards, it overcomes difficulties and finally successfully developed a 16-layer with 7-step interconnection within 24 days.

The boards are delivered to customers as scheduled.

  1. HDI laminated structure analysis:

The conventional product in the industry is HDI with 1-4 steps.

The more the steps, the more probability of multi-layer deviation. This product is a 7-steps 16-layer board with a finished board thickness of 1.8mm. The blind hole structure 7+N+7 is 1-2, 1 -3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, 1-11, 1-12, 1-13, 1-14, 1-15 , 6-12, 10-12, 2-16, 4-16, 5-16, 7-16, 8-16, 9-16, 10-16, 11-16, 12-16, 13-16, 14 -16, 15-16,there are 28 groups of blind holes,and the interconnection of blind holes needs to be made according to the 7-step HDI process, the structure is very complicated, and the processing flow is long.


  1. Connection method:

Conventional core board laminating times are 3 times (multiple laminating will cause the core board to expand and shrink uncontrollably), this product needs to be laminated 7 times through 0809 layer core board stacking and laminating 7 times, laser 7 times, and electroplating filling Hole contacts, of which the 0809 layer is 0.15mm through-hole plating and filling, and the other holes are 0.127mm laser drilling + plating and filling.


  1. Line pre-amplification coefficient:

7 times laminating, pre-amplification is the key, which needs to consider the expansion and contraction of each pressing, so as to give the initial core board (0809 layers) pre-amplification coefficient, this coefficient will directly affect the production of subsequent boards.

  1. Laser drilling:

0710 and 0611 have a large coefficient after the first 2 presses, and the laser machine and LDI machine cannot identify the hole. It is necessary to adjust the laser target and line LDI machine production parameters.

  1. Plating hole and filling with resin:

The number of 0.15mm laser holes is 1000-2000 holes, the area to be plated is small, and it is necessary to repeat the laser 7 times and fill the holes 7 times.

  1. Graphic plating:

Inner layer line width/distance: 0.075/0.075mm, the graphic distribution in the board is isolated, the picture is easy to be filmed by electro-etching, and the line is thin.

  1. Production cycle: Delivery is completed within 24days of the production cycle, and the R&D delivery is successful once.
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