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一、层压板的特性对金属化孔的影响对于高度可靠的印制线路板,材料是很重要的条件。层压板须做到:不产生环氧沾污;可钻质量较好的孔;可进行均匀的化学沉铜。同样,温度、湿度和振动也是引起金属化孔裂缝的直接因素。关于金属化孔的应力,有人提出了如下的关系式。铜层单位表面积上的应力S_c 是:S_C=(y_ey_cA_t(a_e-a_c)ΔT/y_eA_t+2y_cA_c)传递到金属化孔接口部份的弯曲应力的最大值S_(f(max))是。S_(f(max))=5y_cC(a_c-a_c)(ΔT)H/((d_2-d_1)/2)~2y_e:层压材料的弹性模数y_c:铜的弹性模数a_e:层压材料的热胀系数(z 方向)a_c:铜的热胀系数ΔT:温度差A_t:焊盘截面积A_c:金属化孔的截面积2C:焊盘厚度2H:层压材料的厚度d_2:焊盘直径d_1:孔的直径上述关系式中,如a_e 和y_e 均极小,S_c 的
First, the characteristics of laminate metallization holes For highly reliable printed circuit board, the material is very important condition. The laminate must be: no epoxy contamination; drilled holes of good quality; uniform electroless copper immersion. Similarly, temperature, humidity and vibration are also the direct causes of metalized hole cracks. Regarding the stress of metallized holes, the following relation has been proposed. The stress S_c per surface area of the copper layer is: S_C = (y_ey_cA_t (a_e-a_c) ΔT / y_eA_t + 2y_cA_c) The maximum value of bending stress S_ (f (max)) transmitted to the metallized hole interface portion is. S_ f max = 5y_cC a_c - a_c Δ D / d 2 - d 1/2 2y_e: Modulus of elasticity of laminated material y_c: Modulus of elasticity of copper a_e: Thermal expansion coefficient (z direction) a_c: Coefficient of thermal expansion of copper ΔT: Temperature difference A_t: Land cross-sectional area A_c: Cross-sectional area of metallized hole 2C: Land thickness 2H: Laminate thickness d_2: Land diameter d_1: hole diameter In the above relation, if both a_e and y_e are extremely small, the value of S_c