The characteristics of selective welding process are studied by comparing with wave soldering. The most obvious difference between the two is that the lower part of the printed circuit board in wave soldering is completely immersed in the liquid solder.
PCB board is printed with solder paste, installed with electronic components, and then fixed by reflow welding.
Fanyi PCB design Company to military quality PCB design requirement PCB design can not be arbitrary, there are certain rules. Fanyi circuit military quality PCB design has the following requirements
The heat generated during the operation of electronic equipment makes the internal temperature of the equipment rise rapidly. If the heat is not distributed in time, the device will fail due to overheating.
The complexity of PCB production process and process maintenance, especially in chemical wet treatment, make it difficult to prevent the surface foaming defects.
There are three main types of metal substrate: aluminum substrate, copper substrate, iron substrate. Iron substrate is rarely used in the market, here the focus of analysis is aluminum substrate, copper substrate.
In order to prevent oxidation of copper layer in PCB board, separate welding and non-welding parts and protect PCB surface, the color of PCB board is also mainly determined by the color of solder resistance paint.
In PCB proofing, temperature sensitive elements can limit the application of reflow soldering, whether in cartridge or SMD. Therefore, selective welding can be used after reflow welding in most applications.
Industrial circuit boards should pay attention to heat dissipation problems; The second is printed board copper foil line, poor quality circuit board power supply line copper foil is very thin, easy to burn due to the current.
Wiring is generally divided into three levels: one is the layout, which is the most basic requirements of PCB design, the second is to meet the electrical performance, which is the standard to measure whether the circuit board is qualified. Three is beaut
Note for circuit board welding: 1, after getting the PCB bare board, first check the appearance; 2, after the materials required for circuit board welding are complete; 3, when selecting components for welding, welding should be carried out in the order o
Polygon filling deviation usually occurs when polygon plating copper on multi-grid circuit boards. While it does not have a standard based on a single grid, it can provide service beyond the required life of the boards.
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