Solder resistance is an important part of printed circuit board technology. The use of PCB solder solder has become so common that it is most unusual to see that there is no solder for any PCB to resist covering, except for some home built circuits today, and even many prototype boards have solder solder, so its use in commercial production of PCB can be said to be common.
Purpose of welding printed circuit board
As its name suggests, solder shield covers the PCB used to protect the PCB from taking solder to the area of the PCB. In this way only a solder-covered area is actually required, i.e. the area where the component is to be soldered, is free to solder resist, and is capable of welding, which offers many advantages. The main thing is that only whereit has the solder and reaches some areas where corrosion resistance prevents small short circuit caused by the solder bridge can be significantly reduced. This is increasingly important because the very fine spacing of many printed circuit boards today is referred to as resulting in small solder tracks in the welding process that tend to cause Bridges and short circuits. The use of solder resistance limits the areas where the component will be soldered, and these areas can be designed accordingly.
In addition to its function in preventing solder from causing small Bridges, PCB solder also resists acting as a protective layer on the substrate. Solder resistance provides electrical insulation and protection against oxidation and corrosion. Over time this improves the overall reliability of the printed circuit board, especially if it is exposed to harmful reagents.
The role of PCB solder shield and flux
What is PCB flux?
Solder resistance for printed circuit boards is a permanent resin-based coating applied to printed circuit boards during the manufacturing of bare boards. Solder resistance is a permanent coating of a resin preparation, usually green in color, that encapsulates and protects all surface features of a printed circuit board unless it is necessary to form a specific area of solder joints.
Although green is the most widely used color for flux resisters, almost any color can be used. While it can be difficult to maintain accurate colors, it is possible to make them almost any color. However from green, other popular colors besides red and blue.
Apply PCB solder resistance
In order to enable solder resistance layers for printed circuit boards to meet the very precise mounting techniques required for today's surfaces, SMT PCB, liquid sensitive (LPI) solder resist is used. Previously printed circuit boards were soldered using silk screen resisting applications used in stencil printing.
The LPI process for solder resistance is very different from the stencil printing previously used. LPI separates coating and imaging operations, thus achieving the highest level of precision. The material used in PCB solder welding by bare printed circuit board manufacturers is in the form of a liquid photopolymer, and it uses an epoxy resin or epoxy-acrylate resin technique and the entire board is coated with the said material. The thickness of the material is usually about 30 microns to 20 microns above the bare plate of copper. Once the flux is dried after coating the resist material, it is exposed to the desired image pattern and then unrolled to obtain the desired solder resist pattern. The solder is then developed after curing to ensure that it provides a tough lasting finish for heat dissipation.
Washing machine circuit board maintenance what method?
Washing machine is a must for every household household appliances, now there are a lot of washing machine brands on the market, the quality is also good and bad! Of course, no matter how good the brand of washing machine permanent will appear some small problems; Many people in the process of using the washing machine will have problems such as washing machine circuit board, and many people do not know how to prioritize their own check what is the reason; Of course, when the washing machine circuit board problems, how to repair?
With the development of society, science and technology continue to develop, more and more humanized inventions emerge in endlessly, take washing machine as an example, washing machine has semi-automatic to automatic continuous development, bring more and more convenience for people, bring convenience at the same time, it is inevitable that there will be a failure of the washing machine, bring a lot of inconvenience to people, So it's important to know the laundry room circuit board repair.
How much is the washing machine circuit board?
Many people in enough to buy washing machine circuit board before will ask the price, but the price of different washing machine circuit board is completely different, so we first want to know what they want to buy before buying washing machine circuit board, if the United States washing machine computer board (motherboard) generally will not exceed 100 yuan, most between 70-90 yuan.
What is the washing machine circuit board maintenance method?
The washing machine circuit board is broken to be actively repaired, so some people want to know what is the washing machine circuit board maintenance method, what is the washing machine circuit board maintenance method is introduced as follows:
1. Washing machine circuit board maintenance method -- Observe whether the circuit board has been artificially damaged, mainly from the following aspects:
(1) See whether the circuit board was broken, resulting in the deformation of the board Angle, or the chip on the board was broken or deformed.
(2) Observe the socket of the chip to see whether it is forced to break because there is no special tool.
Observe the chip on the circuit board, if there is a socket, first observe whether the chip is inserted wrong.
④ If the circuit board is equipped with short-circuit terminals, observe whether the short-circuit terminals are inserted incorrectly.
2. Washing machine circuit board maintenance method -- Observe whether the components on the circuit board are burned out. Under normal circumstances, even if the resistance is burned, its resistance value will not change, the performance will not change, does not affect the normal use, then you need to use a multimeter to assist measurement. But if the capacitor, diode is burned, their performance will change, in the circuit can not play its due role, will affect the normal operation of the entire circuit, then must be replaced with new components.
3. Washing machine circuit board maintenance method -- Observe whether the integrated circuit on the circuit board is bulging, cracked, burned, black. If this happens, it is almost certain that the chip has burned out and must be replaced.
4. Washing machine circuit board maintenance method - Observe whether the circuit board on the line is peeling, burning and breaking. Whether the copper hole is detached from the pad. Look at the safety on the circuit board (including the fuse and thermistor) to see if the fuse is blown.
Washing machine circuit board maintenance price is generally not particularly expensive, and the maintenance method is very simple, we can fully understand the information, so as to better maintenance of washing machine circuit board, in the case of problems is not anxious not panic, unnecessary to spend more money, easy and simple problems can be solved by themselves.
What happens when the washer capacitor fails?
The following will happen if the washing machine capacitor is broken:
1. If the capacitor of the washing machine is broken, it will cause the washing machine to be unable to work and need to be repaired.
2. If the capacitor is broken, the leakage current will increase. If the insulating medium is damaged for a long time, the leakage current will increase, and then the heating will be damaged.
3, the motor is inductive load, there will be a peak voltage in the operation process, its value will be much higher than the rated working voltage, although not higher than the capacitor voltage, but long-term work in this environment will appear damage accumulation, and then failure.