单项选择题
A.10s~60s; B.60s~120s; C.120s~240s; D.240s~360s;
A.70℃±5℃; B.100℃±5℃; C.125℃±5℃; D.150℃±5℃;
A.0.78ug/cm2 B.1.56ug/cm2 C.2.23ug/cm2 D.3.05ug/cm2
A.超声清洗; B.浸泡清洗; C.喷淋清洗; D.蒸汽清洗;
A.1; B.4; C.12; D.17;
A.侧面焊点长度D可小于引脚宽度W的2倍; B.最大焊料高度E,触及元件体,引脚上部外形不清晰,焊料超出焊盘; C.侧面偏移A要求等于或小于引脚宽度W的25%; D.趾部偏移B超过引脚宽度的25%;
A.润湿角0°<θ≤30°,焊接润湿理想; B.润湿角30°<θ≤45°,焊接润湿良好; C.润湿角45°<θ≤55°,焊接润湿合格; D.润湿角55°<θ≤120°,焊接润湿合格;
A.极性,数值,型号; B.数值,极性,型号; C.型号,数值,极性; D.型号,极性,数值;
A.180℃~220℃; B.200℃~250℃; C.240℃~280℃; D.280℃~350℃;
A.元件与散热件表面充分接触; B.散热件、元器件、连接件装配顺序正确; C.导热材料使用符合要求; D.散热片允许有变形或缺损;