绝对光学编码器达到±0.5 µm精度

In some semiconductor applications, component “multitasking” can lead to axes collisions. Amicra Microtechnologies, a developer and manufacturer of precision assembly systems that bond and mount active/passive semiconductors, lenses, MEMS and processors for microelectronics and micro-optics applications in the automotive, telecommunications and information technology industries found a way to prevent such collisions.

Its NovaPlus series machines handle surface mounting on wafers and stack-die assembly. They use an array of horizontal and vertical axes to perform multiple functions simultaneously. Reliability is critical in avoiding collisions. Incremental measuring systems installed in the company’s machines required reference runs upon commissioning or after a stoppage, and the machines were susceptible to axes collisions without excessive operator attention. Both issues created downtime—intolerable in high-production environments—so the company switched to Renishaw’s Resolute absolute optical encoders. The encoder system allows the machine axes to deliver absolute measurement without reference runs, and the encoders’ position detection method eliminated collisions that led to long periods of downtime. The new encoders help the micro assemblers achieve accuracy of ±0.5 µm and a process capability Cpk of 1.66.

表面安装技术晶圆和堆栈上死去y are used to construct three-dimensional memory and computer structures. Semi-conductors are mounted horizontally and connected (SoC), as well as mounted vertically in several planes (TSV), and miniaturization of electronic components, a driving force behind their design, is dependent on the ability to achieve high packing densities. Amicra’s micro assembly machines use linear axes and special grippers from feed stations to pick up components and position them on boards or wafers where they are bonded or soldered, either conventionally or with a laser beam. The machine simultaneously positions a component while a second handling unit picks up the next component from a buffer store, and work tables and other linear axes with lasers and UV lamps move into position to solder and bond. Concurrently, additional axes position the machine’s integrated process monitoring cameras. These machines have a lot going on at the same time, so process reliability of these installations is particularly important, said Horst Lapsien, managing director of Amicra. More importantly, crashes between the alternate positioning grippers and the linear axes must be avoided. We achieve this through very precise programming of the motions, so the linear axes measuring system’s ability to detect current position of the slides reliably and accurately is paramount.

Incremental position sensors report an incremental change in position and, when powered up, do not report position until they have a reference point. Therefore, starting the NovaPlus’ production and mounting cycle upon commissioning or after a stoppage took a long time. The readheads of all the linear axes had to first travel to a reference position to detect the actual position of the axes, and moving to the reference positions from an undefined slide position also represented a significant source of error. If the operator had not first checked the crash paths and selected the reference travel cycle accordingly, the machines could suffer considerable damage as the result of gripper or gantry collisions.

固定编码器在不参考的情况下立即在开关时立即检测绝对位置，因此机器能够在调试或停止后更快地启动自动循环。Resolute的单轨光学量表将绝对位置和嵌入式相信息结合到单个代码中，以消除与双轨量表相关的脱强调问题。单轨刻度使编码器具有广泛的设置公差，即使轴安装或随着时间的推移，即使轴安装或移动，也可以轻松安装和长期可靠的操作。ReadHead上的积分设置LED提供了一个简单的视觉检查，该检查量表正在正确读取，并进一步简化了安装和诊断。

果断编码器具有独特的位置检测方法，该方法像非常高速数码相机一样运行。强大的数字传感器处理器（DSP）捕获和分析量表的高分辨率图像，该图像应用交叉检查和误差排斥以确定位置为1 nm。编码器与内置位置检查算法结合使用，对污染也具有很高的免疫力。Lapsien补充说，在三转生产操作中，由于肮脏的测量磁带引起的系统的读数，我们的机器记录了零停止。

果断系统的RTLA绝对测量量表可以直接粘合到基板上，也可以插入由不锈钢制成的特殊Fastrack指南中。编码器在Amicra机器中易于安装，可实现±5 µm/m的精度。

Another advantage is the encoder’s use of BiSS-C open serial protocol, which allows it to be integrated into many positioning axes. Many industry-standard servo drives and controls use this interface, added Lapsien. So, the open protocol allows us to avoid getting tied to a single supplier of motion system components.

Renishaw Inc
www.renishaw.com