Method for improving recession of large blind hole

Abstract

The invention relates to a method for improving the recession of a large blind hole, which is used for filling the large blind hole with the blind hole diameter of more than or equal to 5mil and morethan or equal to 10mil on an inner layer anylayer, and comprises the following steps of: filling and leveling up the drilled large blind hole by adopting a whole plate electroplating mode after laserdrilling and chemical copper deposition; and then polishing and grinding the copper surface at the large blind hole in a manner of outer-layer patterning, copper reduction and plate grinding in sequence to improve the recession of the large blind hole. According to the method for improving the large blind hole recession, the flatness of the blind hole reaches 95% or above by optimizing an existingblind hole filling process, the large blind hole recession is greatly improved, the product quality is improved, meanwhile, the procedures of carrying, reworking and the like are omitted, the productquality is improved, and the production cost is effectively reduced.

Description

technical field [0001] The invention relates to the technical field of circuit board production, in particular to a method for improving the depression of large blind holes. Background technique [0002] With the development of electronic information, customers have higher and higher requirements for products. In the process of making anylayer, the blind holes in the inner layer often need to be filled to ensure the diameter of the blind hole laser drilled in the second outer layer plating process and the subsequent hole filling. quality. [0003] For traditional blind holes (diameter 2.5-5mil, hole depth AR≤1:1), the whole board can be filled and leveled at one time by filling and plating. The inner layer contains large blind holes (10mil≥blind hole diameter≥5mil). Because the hole diameter is too large, it is made by traditional whole board electroplating. Increased the difficulty of laser drilling of blind holes in the sub-outer layer or outer layer conduction position ...

AI Technical Summary

Problems solved by technology

[0005] ① After copper sinking, graphics pre-processing cannot be done, and the film needs to be pressed manually directly. There are operational problems such as scratches and finger prints during board transportation. In addition, because the copper sinking layer is too thin (0.3-0.6 μm), there will be oxidation and shedding for a long time Risk, need to be controlled Hold time must be completed within 4h from the line to the plated blind hole;

[0006] ②Plating hole dry film is required after copper sinking, because the sinking copper layer is too thin (0.3-0.6μm), and the amount of copper bite in the pre-treatment of the circuit is 0.8-1.5μm, which is greater than the thickness of the sinking copper layer, so it cannot be directly pressed after pretreatment film, but the pre-treatment, the surface roughening is not enough, it is easy to have abnormal quality such as dirty film, deep plating of plated holes, etc.;

[0007] ③Due to the use of plated blind holes, there are differences in the density of blind holes, resulting in uneven blind holes at the position of plated blind holes. After electroplating, the film needs to be removed, and the abrasive belt is used to grind the plate. After pressing, the bottom copper is too thin, and the blind hole position is copper-plated If it is too thick, the position of the blind hole is too large, and there is a blind hole at the raised position of the abrasive belt grinding, which is easy to pull off the blind hole, that is, there is a risk of excessive range and exposed copper after grinding the plate, which makes it more difficult to etch the line ;In addition, due to plated blind holes and unplated surface copper, there is a certain loss of surface copper on the abrasive belt, and the copper behind the abrasive plate is too thin, resulting in the need for rework and thicker plating after the subsequent abrasive belt to ensure the customer's minimum surface copper

[0008] The plated holes are used to make blind holes, the area of ​​the plated holes is small, and the output current ratio is reduced, resulting in low efficiency. At the same time, there is a difference in the distribution density of blind holes in the plated blind hole position, resulting in different efficiency of plated holes in dense positions and independent positions during the electroplating process. , there is a difference in copper plating thickness between the dense position and the sparse position, resulting in a difference in the raised position, and there is a risk of pulling the blind hole off during the grinding process of the abrasive belt

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