Chemical fine resistance adjusting method and etchant for resistor embedded in nickel-phosphorus layer

Abstract

The invention discloses a chemical fine resistance adjusting method for a resistor embedded in a nickel-phosphorus layer, and belongs to the technical field of circuit boards. The method mainly solvesthe technical problem that a conventional resistance adjusting method cannot finely and uniformly adjust a resistance value. The method comprises firstly measuring the initial resistance value R1 ofa resistor before resistance adjustment; and obtaining the target resistance value R2 of the resistor by controlling the immersion time T of the resistor in an etchant for etching a nickel-phosphorusalloy layer. The invention discloses a chemical fine resistance adjusting etchant for a resistor embedded in a nickel-phosphorus layer. The method etches the nickel-phosphorus alloy layer uniformly, and can finely control the change of the resistance by controlling the time so as to obtain the target resistance value and improve the resistance control precision.

Description

technical field [0001] The invention relates to the technical field of circuit boards, and more specifically relates to a method for chemically fine-tuning resistance embedded in a nickel-phosphorus layer and an etchant. Background technique [0002] As a method to replace the surface resistor patch, the PCB embedded resistance process can save the increasingly tight surface space of the PCB, and it is also more reliable than the chip resistor. Using nickel-phosphorus alloy buried resistance copper foil is one of the realization methods of buried resistance board. [0003] Nickel-phosphorus alloy buried resistance copper foil refers to a special copper foil material made by sputtering or electroplating a layer of nickel-phosphorus alloy 2 on the copper foil 1. Its structure is as figure 1 shown. Among them, the thickness of the nickel-phosphorus alloy material is mostly controlled at 0.1 μm to 0.4 μm. [0004] A nickel-phosphorus alloy buried resistance plate is formed b...

AI Technical Summary

Problems solved by technology

[0006] However, after the buried resistance circuit is formed, the circuit board still needs to undergo subsequent processes such as solder resistance and surface treatment. In the pre-treatment of the subsequent process, the buried resistance layer (nickel-phosphorus alloy layer) is often corroded, resulting in changes in the thickness of the buried resistance layer. The impact on the resistance value is not as precise and controllable as the pattern etching process, which often leads to the resistance value of the board after the pre-soldering treatment is smaller than the design target value; in view of the above-mentioned problem of small resistance value, the existing control method or through laser Ablating part of the copper foil in contact with the square buried resistance, or re-ablating a compensated buried resistance pattern around the hole by laser, there is a problem that the laser ablation of the copper surface will affect the nickel-phosphorus alloy layer. These are fine Obstacles to uniformly adjust the resistance value, causing the adjusted resistance value to fail to meet expectations, which is unacceptable for buried resistance circuit board products with high resistance requirements

Images