1) PCB defect circle hole
PCB缺陷圆孔
3) Round-hole defect
圆孔状缺陷
4) PCB fault detecting
PCB 缺陷检测
5) roundness fault
圆形缺陷
1.
In the light of the status that there are caustic faults in the oil well tubing and there are not effective inspections, in this paper the plane roundness fault model of the is studied, and the magnetic leakage flux distributing model at the direction of the normal of the roundness fault is proposed.
针对油管容易遭到腐蚀性损伤而目前缺乏有效检测手段的现状，本文系统的研究了平面圆形缺陷模型，提出了圆形缺陷的法线分量漏磁场的实验分布模型。
6) blowhole defect
气孔缺陷
1.
It was believed after the reason analysis that the blowhole defect was caused by the gas evolution of sand cores after being heated and the improper pouring system design which leading to the gas immixture.
介绍了493Q气缸盖的铸造工艺,分析认为气孔缺陷是因砂芯受热分解与浇注系统不合理裹入气体导致。
补充资料：PC
聚碳酸酯(双酚A型)化学名称2，2-双(4-羟基苯基)丙烷聚碳酸酯，是由酯交换法和光气化法制得。平均分子量3.57×104。无定形透明颗粒．无味、天臭、无毒。相对密度1．20-1.43。没有明显熔点，220-230℃呈熔融状态。透光率高，吸水性低，耐冲击，韧性好．蠕变小，制品尺寸稳定。耐热性和耐寒性较好．玻璃化温度149-150℃．热变形温度135℃(1．82MPa)、分解温度＞310 ℃，脆性温度－l00 ℃，使用温度-100～120 ℃。耐稀酸、耐油、不耐碱。溶于二氯甲烷、二氯乙烷、氯仿、三氯乙烯、四氯乙烷、四氢呋喃、三甲酚、磷酸三甲酯等。疲劳强度较低，容易产生应力开裂。具有优良的高温电性能，具有耐燃自熄性。拉伸强度 ＞60MPa, 伸长率＞60％，弯曲强度＞95MPa。
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参考词条