焊点

The modal tests of PCB and PCB assembly (free boundary condition and fixed boundary condition) were carried out. The equivalent elastic modulus and damping parameters of PCB can be gained, and the fixed boundary condition of finite element model was also determined. These will help to the following work. Second, drop impact tests of three different heights were carried out. Strains and acceleration responses of PCB were measured. Failed BGA packages of different test conditions were dyeing, and cross section analysis of failed solder joints was conducted. It was found in our drop tests that the root cause of lead-free solder joints under drop impact was the combined effect of mechanical shock and PCB bending vibration.

针对JEDEC标准试件的局限性，提出了设计便于统计学研究焊点可靠性的试验试件的构想，利用有限元模态分析方法确定并验证了用圆形PCB组件替代JEDEC标准试件的可行性；通过一系列模态试验和有限元模态分析，确定了圆形PCB组件的相关试验参数，这不仅为跌落碰撞下PCB组件有限元模拟确定了较为合理准确的有限元模型，而且为正确地评价跌落碰撞下PCB组件的可靠性问题奠定了基础。

The effect of electrode wear on indentation depth and weld quality was studied for welding galvanization steels.

进而分析了点焊镀锌板的电极磨损对压痕深度与焊点质量的影响。

Assembly of Advanced packages such as Ball Grid Array and Chip Size Package.

先进封装的装配，如球形焊点阵列和芯片尺寸封装。

The interfacial reactions and reliability of lead-free solder joints are systematically investigated in this thesis.

本文对无铅电子封装中的界面反应和焊点可靠性进行了系统的研究。

It is proved that thermal fatigue is the main cause of the invalidity of the package.

实践证明热作用是芯片封装组件失效破坏的主导因素，因此热循环条件下的焊点可靠性研究有着非常重要的意义。

I have forwarded your photo to our manufacturing teams and they will keep a sharp eye on the cosmetics at the regulators.

我将把你的照片发给我们的加工部门，让他们更加注意元件焊点的美观。

People has been committed to hunting for the alternative leadless products of lead solders, and found that the lead-free solder joints often display some special defects in the long-term use of them. The serious lift-off phenomenon has gradually aroused people's attention.

人们致力于寻求含铅钎料的无铅替代产品，并在长期使用过程中发现无铅钎料焊点会产生某些特殊的缺陷，其中较为严重的剥离现象也逐渐引起人们的重视。

The pleunm anti-static insulated material housing prevents short circuit led by the contact of welding spot and the metal channel of word sign. At the same time, the circuit uses particular constant current design and lightning arrester. Silicon rubber leads between modules of anti-aging and anti-cracking guarantee the long-term work in bad environment of open area while the low resistance of lead reduces the affection to the emitting brightness of LED by voltage drop.

其外壳采用阻燃防静电绝缘材料，可防止 PCB焊点与金属字槽壳的接触而产生短路，同时电路采用独特恒流电路设计及雷电吸收装置，模组间连接线采用软硅橡胶导线，在恶劣的户外恶劣环境下长时间使用，导线不会老化脆裂，同时导线内阻比较小，降低压降对LED发光亮度的影响。

This paper discussed the mathematical model of speed control for keeping linear velocity of the welding torch with soldered dot on ellipse circumference constant.

主要讨论为保证焊枪相对于椭圆圆周上的焊点线速度恒定而进行的速度控制，以及保持焊枪始终在工件的焊接轨迹上而进行的位置控制的数学模型。

The consumption of metallization was also greatly influenced by the coupling effect.

该现象对焊点可靠性的设计和评估具有重要指导意义。

On the other hand, the more important thing is because the urban housing is a kind of heterogeneity products.

另一方面，更重要的是由于城市住房是一种异质性产品。

Climate histogram is the fall that collects place measure calm value, cent serves as cross axle for a few equal interval, the area that the frequency that the value appears according to place is accumulated and becomes will be determined inside each interval, discharge the graph that rise with post, also be called histogram.

气候直方图是将所收集的降水量测定值，分为几个相等的区间作为横轴，并将各区间内所测定值依所出现的次数累积而成的面积，用柱子排起来的图形，也叫做柱状图。