HOW TO PREVENT PCB BOARD WARPING?
AKEN Cheung 封装基板制造商
Director . Advanced packaging IC substrate manufacturer. Advantages: Cost reduction with realiability. FCBGA/ FCCSP/ CSP/ SiP/ Module/ BGA memory DDR3/DDR4/DDR5/ mmwave/ Embedded/ PCB substrate, uHDI PCB etc. mSAP
Circuit board warpage will cause the components are not allowed positioning; bending in the SMT, THT, the components of the pin is not the whole, will bring a lot of assembly and installation work difficult.
IPC-6012, SMB-SMT circuit board maximum warpage or twist 0.75%, other board warpage is generally not more than 1.5%; electronic assembly plant to allow warpage (double / multi-layer) is usually 0.70 — 0.75%, (1.6mm thickness) In fact, many boards such as SMB, BGA board requirements warpage less than 0.5%; part of the plant even less than 0.3%; PC-TM-650 2.4.22B
Warpage calculation method = warpage height / curved length
Circuit board warpage prevention:
The same time as the above-
1, engineering design: interlayer prepreg arrangement should be corresponding; multi-layer board and semi-cured film should use the same supplier products; outer C / S surface area as close as possible, you can use an independent grid;
The same time as the above-
2, before the baking sheet
The same time as the above-
Generally 150 degrees 6 – 10 hours, remove the board of water vapor, and further make the resin cured completely, to eliminate the stress within the board; open before the baking, whether inside or double-sided are needed!
3, multi-layer laminated laminated plate should pay attention to the plate before the curing of the latitude and longitude direction:
The same time as the above-
The ratio of the latitude and longitude to the shrinkage ratio is not the same, the pre-lamination of the pre-laminated material before the separation of the latitude and longitude direction; core cutting should also pay attention to the latitude and longitude direction; general plate curing film roll direction;
4, the thickness of the pressure to eliminate the pressure plate after the cold, pruning burr;
The same time as the above-
5, before drilling baking: 150 degrees 4 hours;
6, the thin plate is best not through the mechanical grinding brush, the proposed use of chemical cleaning; plating with a special fixture to prevent bending bending plate
The same time as the above-
7, spray tin rear in the flat marble or steel plate naturally cooled to room temperature or air floating bed after cooling;
The same time as the above-
Warping plate handling:
The same time as the above-
150 degrees or hot pressure 3 – 6 hours, the use of smooth steel plate weight, 2-3 baking!