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表面安装的焊区图形确定了焊接元件的位置,它对实现电连接并满足所要求的机械强度十分重要。因此,位置的确定对SMT的可靠性起着重要的作用。我们已经提出过有关表面安装焊区图形设计的一些原则和公式。这些原则和公式是在实验数据的基础上取得的,而且对某种用途的适用性是根据本文所论述的实验条件来拟定的。对于每一个公式来说,定义了一个常数K就是为了适应元件公差和应用上的差异。本文所提出的这些设计公式和设计原则的含义可归纳如下: 1.两个相邻焊点的中心距等于两个相邻元件引线之间的中心距。 2.焊点的宽度应当等于元件引线或端电极宽度加上或减去一个常数。 3.焊点的长度是根据要焊元件的端电极/引线的高、宽和接触点或元件的面积来确定的。就焊接的可靠性来说,焊点长度比焊点的宽度更为重要。 4.焊接图形的两个相对焊点之间的间隙是根据元件本身的宽度和尺寸公差来确定的,而且它对于焊点上合理的排布元件至关重要,该间隙既影响到可靠性也影响到焊接质量。 5.封装间隙,元件的方向和通孔位置对SMT的制造性能都是非常重要的。
Surface mounted land patterns define the location of the soldered components and are important for achieving electrical connections and meeting the required mechanical strength. Therefore, the location of the SMT reliability plays an important role in determining. We have already presented some principles and formulas for the design of surface mount landforms. These principles and formulas are based on experimental data and the suitability for a given use is based on the experimental conditions discussed in this article. For each formula, a constant K is defined to accommodate component tolerances and application differences. The meanings of these design formulas and design principles presented in this paper can be summarized as follows: 1. The center distance between two adjacent solder joints is equal to the center distance between the leads of two adjacent components. 2. The width of the solder joint should be equal to the element lead or terminal electrode width plus or minus a constant. 3. The length of the solder joint is determined by the height, width and contact area of the terminal electrode / lead of the component to be welded or the area of the component. In terms of soldering reliability, the solder joint length is more important than the solder joint width. 4. The gap between the two opposing solder joints of the solder pattern is determined by the width and dimensional tolerance of the component itself and is critical to the proper arrangement of components on the solder joint which affects both reliability Affect the quality of welding. 5. Package gap, component orientation and through-hole location of SMT manufacturing performance are very important.