Mainland China has the largest production capacity for printed circuit board (PCB) globally, as well as the most complete supply chain. Taiwanese businesses are the main supplier in the Chinese PCB supply chain. Based on the existing investment data, this study aims to explore and forecast the areas which are worth developing for Taiwanese PCB businesses. Through the association rules to explore data, this research intends to identify the association among the PCB industrial areas in which Taiwanese businesses are invested. Data for this study are obtained from the Taiwan Economic Journal to analyze Taiwan Stock Exchange Companies and over-the-counter-listed firms on PCB investment by Taiwanese businesses in Mainland China. The main findings include that Kunshan, Suzhou, and Shenzhen are the investment focus for the upstream and mid-stream manufacturers, and the investment level in Shanghai is higher than in the other places for the downstream manufacturers. For the upstream and mid-stream manufacturers, Changshu is another area worthy of investment for firms. Changshu and Dongguan can be the choice for the midstream manufacturers. The research results can serve as a valuable reference for Taiwanese businesses.