ASE Technology Holding Co Ltd is a semiconductor assembly and testing firm. The company operates in segments: Packaging, Testing, and Electronic Manufacturing Services. Of these, packaging services contribute the most revenue. It involves packaging bare semiconductors into completed semiconductors with improved electrical and thermal characteristics. The Testing Segment includes front-end engineering testing, wafer probing, and final testing services. In the EMS segment, the company designs manufacture and sells electronic components and telecommunication equipment motherboards. The company is based in Taiwan but garners over half its sales from firms in the United States.ASE Industrial Holdings Co Ltd, formerly Advanced Semiconductor Engineering Inc, offers semiconductor packaging and testing services including semiconductor packaging, production of interconnect materials, engineering testing and wafer probing.