PCB Technical - PCB circuit board manufacturing principles and basic knowledge

Basic knowledge of PCB circuit board The circuit board is based on an insulating board, cut into a certain size, with at least one conductive pattern attached to it, and holes (such as component holes, fastening holes, metallized holes, etc.) It replaces the chassis of the electronic components of the previous device, and realizes the mutual connection between the electronic components.

PCB circuit board repair is an emerging repair industry. In recent years, the degree of automation of industrial equipment has become higher and higher, so the number of industrial control boards in various industries has also increased. After the industrial control board is damaged, the high cost required to replace the PCB circuit board (as little as several thousand yuan, as many as Tens of thousands or hundreds of thousands) has also become a very headache for enterprises. In fact, most of these damaged PCB circuit boards can be repaired in China, and the cost is only 20%-30% of the purchase of a new board, and the time taken is much shorter than that of foreign boards. The following introduces the basic knowledge of PCB circuit board repair:

Almost all PCB circuit board repairs do not have drawings and materials, so many people are skeptical about PCB circuit board repairs. Although various circuit boards are very different, the same thing is that each PCB circuit board is composed of various integrated blocks and resistors., Capacitors and other components, so the damage of the PCB circuit board must be caused by one or some of the components. The idea of PCB circuit board maintenance is established based on the above factors. Circuit board repair is divided into two parts: inspection and repair, of which inspection occupies a very important position. The basic knowledge of repairing each device on the PCB circuit board is tested, until the bad parts are found and replaced, then a PCB circuit board is repaired.

PCB electrical testing is the process of finding, determining and correcting the faults of each electronic component on the PCB circuit board. In fact, the entire inspection process is a thinking process and a test process that provides logical reasoning clues. Therefore, the inspection engineer must gradually accumulate experience and continuously improve the level of PCB circuit board maintenance, testing, and repair. General electronic equipment is composed of thousands of components. During maintenance and overhaul, it will be very time-consuming and difficult to implement if the problem is found by directly testing and inspecting every component in the PCB board. very difficult. Then the check-in type inspection method from the fault phenomenon to the cause of the fault is an important method of inspection and repair. As long as the PCB circuit board detects the problem, it is easy to repair.

Single-sided rigid printed circuit board: - single-sided copper clad laminate - blanking - (brushing, drying) - drilling or punching - screen printing circuit anti-etching pattern or using dry film - curing inspection and repairing board - etching copper - removing corrosion Printing, drying - brushing, drying - screen printing solder mask graphics (commonly used green oil), UV curing - screen printing character marking graphics, UV curing - preheating, punching and shape - electrical opening, short circuit test - brushing, drying - Pre-coated soldering anti-oxidant (drying) or spraying tin and hot air leveling - inspection and packaging - finished products leave the factory.

Double-sided rigid printed board: -Double-sided copper clad laminate - blanking - stacking - CNC drilling through holes - inspection, deburring and brushing - electroless plating (through hole metallization) - (full board electroplating of thin copper) - inspection Brushing - screen printing negative circuit patterns, curing (dry film or wet film, exposure, development) - inspection, repairing - circuit pattern plating - tin electroplating (anti-corrosive nickel/gold) - removing printing material (photosensitive film) - etching Copper-(Remove Tin)-Cleaning and Scrubbing-Screen printing solder mask graphics commonly used thermal curing green oil (photosensitive dry film or wet film, exposure, development, thermal curing, commonly used photosensitive thermal curing green oil)-cleaning, drying-screen printing Mark character graphics, curing-(spray tin or organic solder mask)-shape processing-cleaning, drying-electric continuity inspection-inspection packaging-the finished product leaves the factory.

In PCB design and manufacturing, through-hole metallization method for manufacturing multilayer board process - double-sided cutting of inner copper clad laminate - brushing - drilling positioning holes - sticking photoresist dry film or coating photoresist - Exposure - development - etching and film removal - inner layer roughening, deoxidation - inner layer inspection - (outer layer single-sided copper clad circuit production, B-stage bonding sheet, board bonding sheet inspection, drilling positioning holes) - layer Press-number control drilling-hole inspection-hole pretreatment and electroless copper plating-full plate thin copper plating-plating inspection-sticking photo-resistant electroplating dry film or coating photo-resistant electroplating agent-surface layer bottom plate exposure-development, Repairing - circuit pattern plating - tin-lead alloy plating or nickel/gold plating - film removal and etching - inspection - screen printing solder mask or photo solder mask - printing character graphics - (hot air leveling or organic solder mask )-CNC washing shape-cleaning, drying-electric on-off inspection-finished product inspection-packing and leaving factory.