Method of prevention and treatment of warp of PCB sample making.As the production personnel of shenzhen PCB board, everyone will see or encounter the phenomenon of PCB warping. The warping of shenzhen PCB board will result in inaccurate positioning of components.When the plate is bent on SMT and THT, the improper pins of the components will bring a lot of difficulties to the assembly and installation. Then how to prevent the buckling of shenzhen PCB board? Here is a detailed explanation:
Ipc-6012, SMB-- the PCB of SMT has the maximum warpage degree or warpage degree of 0.75%, and the warpage degree of other boards generally does not exceed 1.5%.The warp (double-sided/multi-layer) allowed by the electronic assembly plant is usually 0.70---0.75% (1.6mm thickness). Actually, many boards, such as SMB, require the warp of BGA boards to be less than 0.5%.Some factories are even less than 0.3%.
PC - TM - 650 2.4.22 B
Warping calculation method = warping height/warping length
Prevention of PCB warping in shenzhen:
Interlaminar semi-solidified sheet arrangement response;The multi-layer core board and semi-solidified sheet of shenzhen PCB board shall use the same supplier product;The figure area of outer C/S surface is as close as possible, and independent grid can be adopted.
Generally 150 degrees 6 to 10 hours, remove the moisture in the plate, further solidify the resin completely, eliminate the stress in the plate;Before starting the material, both inner layer and double side are needed!
3.Attention should be paid to the longitude and latitude direction of the plate curing plate before laminated laminated plate:
The percentage of warp and weft contraction is different. Before lamination of semi-solidified sheet of shenzhen PCB, pay attention to distinguish the warp and weft directions.The direction of warp and weft should also be paid attention to when feeding the core plate.Generally, the winding direction of plate curing sheet is meridional.The long direction of copper clad plate is meridional.
4.The thickness of the proofing layer of shenzhen PCB plate eliminates the stress after the pressure plate is pressed and the rough edges are trimmed.
5.Dry plate before drilling: 150 degrees for 4 hours;
6.It is recommended to use chemical cleaning instead of mechanical brush.Special clamp is used for plating to prevent plate bending and folding
7.After spraying tin, cool on flat marble or steel plate until room temperature or air float bed is cooled.Warping plate treatment: 150 degrees or 3 to 6 hours of hot pressure, using smooth and flat plate pressure, 2 to 3 times of baking.