When the PCBA board is passing reflow soldering 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, China PCB assembly factory-SysPCB will analyze the reasons for the deformation of the PCBA board.
Each circuit board will have a maximum TG value. When the reflow temperature is too high and higher than the maximum TG value of the circuit board, the board will soften and cause deformation.
With the popularity of lead-free technology, the temperature of the furnace is higher than that of lead technology, and the requirements for the CCL are also higher and higher. The lower the TG value of the PCB board, the easier it is to deform when passing through the furnace, but the higher the TG value, the more expensive the price.
With the development of electronic products in the direction of small and thin, the thickness of the circuit board is also becoming thinner and thinner.
When the circuit board is reflowed, it is generally placed on the chain for transmission. The chains on both sides are used as support points. If the size of the circuit board is too large or the number of panels is too large, it is easy for the circuit board to sunk to the middle point, resulting in deformation.
V-Cut will destroy the board structure. V-Cut cuts a groove on the original large sheet of board. Too deep V-Cut line will lead to the deformation of the PCBA board.
Generally, a large area of copper foil is designed on the circuit board for grounding, and sometimes the Vcc layer is also designed with a large area of copper foil. When these large areas of copper foil cannot be evenly distributed on the same circuit board, it will cause the problem of uneven heat absorption and heat dissipation. Of course, the circuit board will also expand and contract. If the expansion and contraction cannot be done at the same time, it will cause different stress and deformation. At this time, if the temperature of the board has reached the upper limit of the TG value, the board will begin to soften, causing permanent deformation.
Today's circuit boards are mostly multi-layer boards with many drilled connection points. These connection points are divided into through holes, blind holes, and buried holes. These connection points will limit the effect of thermal expansion and contraction of the circuit board, lead to deformation of the board.