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How To Prevent PCB Warping?
January 2, 2018 22:56:41 Reply
Warping the board will cause the components to be misaligned. When the board is bent at SMT or THT, the components and pins are not complete, which can create difficulties in assembly and installation.
IPC-6012, SMB-SMT board maximum bending is 0.75%, other boards generally less than 1.5% of the bending; electronic assembly plant allows the warp (duplex / multilayer) Typical 0.70 --- 0.75% , (1.6mm thick). In fact, many boards such as SMB, BGA boards require less than 0.5% warpage. Some factories are less than 0.3% PC-TM-650 2.4.22B
Warpage calculation method = warpage height / warpage length
Prevent board warpage:
1, Engineering design: prepreg layout should correspond to each other. Multilayer core and prepreg should use the same supplier products. External C / S surface area should be as close as possible and use an independent power grid.
2, Drying board before produce
Usually 150 degrees 6-10 hours, remove the water vapor inside the board, completely cured resin, eliminate stress within the board; preheat baking board, either internal or both need!
3, Multi-layer composite board before curing should be noted that the latitude and longitude direction:
4, Drying before drilling: 150 degrees 4 hours;
5, The board had better without mechanical brushing, it is recommended to use chemical cleaning; use special fixtures when plating to prevent the folding plate folded
Warping plate processing:
150° Hot pressing 3 - 6 hours, with flat and smooth steel pressure, 2-3 times baking!
January 3, 2018 19:50:29 Reply
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