Method for solving problem of solder resist photosensitive white oil pencil marks

Abstract

The invention discloses a method for solving the problem of solder resist photosensitive white oil pencil marks. The method comprises the steps that a metal substrate is pretreated through sand blasting or volcanic ash; crude oil and printing ink are standardized by manufacturers: the viscosity is controlled to be 140-170 dga.s; the metal substrate is printed through a screen printing machine, andthe thickness of ink on the circuit surface is controlled to be 20-30 [mu]m; the metal substrate stands for 30 min at the corresponding position after being printed each time; the metal substrate ispre-baked for the first time at the temperature of 75 DEG C for 32 minutes; after the metal substrate is pre-baked for the first time, after the printing ink is cooled, pre-baking for the second timeis performed at the temperature of 80 DEG C for 13 minutes; and the exposure grade of a 21-grade exposure ruler is controlled to be 9-13. According to the invention, through the pre-baking mode afterprinting is optimized, the method solves the problem of high-reflectivity solder resist white oil pencil marks, and meanwhile, the ink hardness is improved, traces left on the surfaces of the processing inks are avoided, pencil marks cannot be generated in the subsequent processing process, the appearance requirements of users are met, the reflectivity of the ink is reserved, and the ink can be popularized and used in the industry.

Description

technical field [0001] The invention relates to the technical field of solder resist prebaking, in particular to a method for solving solder resist photosensitive white oil pencil marks. Background technique [0002] Pencil print: The marks left by the metal when it collides / rubs on the ink surface, similar to the scratches of a pencil on paper, which can be wiped off with an eraser. [0003] Ink is the coat of the printed circuit board, it is to prevent short circuit caused by moisture, chemicals, etc. FR4 printed circuit boards have gradually developed into metal-based printed circuit boards, and the reflectivity requirements of solder resist white ink are also getting higher and higher; during PCB production and processing and SMT placement, metal-based printed circuit board stacks collide Pencil marks are caused when the product is reflected, which affects the reflective rate of the product and brings great troubles to the industry; the current improvement methods: ① Us...

AI Technical Summary

Problems solved by technology

[0003] Ink is the coat of the printed circuit board, it is to prevent short circuit caused by moisture, chemicals, etc. FR4 printed circuit boards have gradually developed into metal-based printed circuit boards, and the reflectivity requirements of solder resist white ink are also getting higher and higher; during PCB production and processing and SMT placement, metal-based printed circuit board stacks collide Pencil marks are caused when the product is reflected, which affects the reflective rate of the product and brings great troubles to the industry; the current improvement methods: ① Use ink with good scratch resistance, which needs to be specially developed by the ink supplier; ② Increase the wattage of the exposure lamp tube to increase The exposure time is used to increase the exposure level, which can easily lead to poor exposure; ③Two printings and two alignment methods are used, the first printing ensures the thickness of the substrate and independent line ink, and the second printing ink is thinner to increase the penetration of exposure However, this method has a long process, low efficiency, and no obvious improvement; ④In the PCB process, a protective film is added to protect the ink surface, but there is also the problem of pencil marks in the SMT patch operation. Therefore, solder resist white with high reflectivity Oil pencil printing is an improved project in the industry