When the PCBA board is reflowing and wave soldering, the PCBA board will be deformed due to various factors, resulting in poor PCBA soldering, which has become a headache for production personnel. Next, we will analyze the reasons for the deformation of the PCBA board.
1. The reflowing temperature for PCBA board
Each board will have the largest TG value. When the reflowing temperature is too high, higher than the maximum TG value of the board, it will cause the board to soften and cause deformation.
2. PCB material
With the prevalence of lead-free processes, the lead free processes temperature of the reflowing is higher than that of lead processes, and the PCB material requirements also to be higher and higher. The lower the TG value of the board, the easier it is to deform during reflowing, but the higher the TG value, the more expensive it is.
3. The thickness of PCBA board
With the development of electronic products in a small and thin direction, the thickness of the circuit board is becoming thinner and thinner, and the thinner the thickness of the circuit board, the high temperature is more likely to cause deformation of the board during reflow soldering.
4. PCBA board size and number in panels
When the circuit board is reflowing, it is generally placed on the chain for transmission. The chain on both sides serves as a support point. If the size of the circuit board is too large or the number in the panel is too much, the circuit board is easily recessed toward the intermediate point to cause deformation.
5. The depth of V-Cut
V-Cut will damage the structure of the board. V-Cut cuts the groove on the original board. The V-Cut line will cause deformation of the PCBA board.
6. Uneven copper area on PCBA board
Generally, a large area of copper foil is designed for grounding. Sometimes the Vcc layer is also designed with a large area of copper foil. When these large areas of copper foil are not evenly distributed on the same circuit board, then will cause the problem of uneven heat absorption and heat dissipation speed. When these large-area copper foils are not evenly distributed on the same circuit board, the heat absorption and heat dissipation speed will be uneven. The circuit board will of course be expand with heat and contract with cold. If the expansion and contraction cannot at the same time, then will make different stresses and cause deformation, if the temperature of the board has reached the upper limit of the TG value at this time, the board will begin to soften and cause permanent deformation.
7. Connection points of the each layers on the PCBA board
Today's circuit boards are mostly multi-layer boards, which have a lot of connection points for drilling holes. These connection points are divided into through holes, blind holes and buried holes. These connection points limit the thermal expansion and contraction of the circuit board causes deformation of the board.
The above is the main reason for the deformation of the PCBA board. During the PCBA processing, can prevent these reasons, which can effectively reduce the deformation of the PCBA board.
