本研究分別以資產報酬率（ROA）以及Tobin''s Q值兩項來做為公司價值代理變數，以台灣高科技資訊電子業為對象，檢定資訊電子公司研發密度是否存在著一上下不對稱之非線性門檻關係，透過縱橫門檻模型（Panel Threshold），期望找出高科技電子業之最適研發密度，使公司價值達到極大化。 實證結果顯示，以Tobin''s Q值為公司價值代理變數時存在雙重門檻效果，研發密度門檻值分別為2％以及11％，因此企業研發密度可分為三個區間。其中第二區間為當企業研發密度介於2％和11％時，其與公司價值呈現顯著正相關，在此區間研發密度的提高將會使公司價值最有效提高。第三區間為當企業研發密度高於11％時，此時與公司價值呈現顯著負相關，亦即代表著高科技電子公司若過度投入研發，則可能使公司投入之研發產生反效果，將使得公司價值不增反減。 故高科技電子公司適當之研發投入，雖無法明顯提高會計盈餘帳面上已實現之公司價值與經營績效，但卻能有效提高公司內部無形資產與未來成長機會。 This study tries to examine the asymmetrical nonlinear threshold effect about the density of R&D of electronic companies by observing high-tech and electronic industry in Taiwan. And return of asset and Tobin''s Q are treated as proxy for the value of firms. The goal is to find out the best density of R&D of high-tech and electronic industry and to make the value of firms maximum through panel threshold model. The result shows that double threshold effects exist when Tobin''s Q is considered as proxy for the value of firms. The threshold values of the density of R&D are 2％ and 11％, so that the density of R&D of firms are divided into three levels. The second level of the density of R&D is between 2％ and 11％. In this level, the density of R&D and the value of firms are obviously positively related, and increasing the density of R&D will improve the value of firms efficiently. In the third level where the density of R&D is higher than 11％, the density of R&D and the value of firms are negative relation obviously. In other words, if the electronic companies invest excessively in R&D, it may not bring them benefits but waste. Although the R&D input of high-tech and electronic companies can not increase the realized value of firms and operating achievement of accounting return significantly, it can accelerate invisible assets and the growing chance of firms in the future.