Collaborative innovation is an important way for enterprises to strengthen innovation ability. With the increasingly complicated technology and fierce market competition, cooperation among firms is meaningful for industrial transformation and upgrading. Collaborative innovation has been widely taken into practice. For example, a survey invested by National Bureau of statistics reveals that 25.3% of industrial enterprises above scale invested in collaborative innovation in 2014. Given the importance of collaborative innovation, extant literature investigates the determinants of collaborative innovation activities, including marketization, legal environment, government regulation and industrial policy. However, most of the studies emphasize the role of formal institutions and little attention concerns about informal institutions, such as social capital, religion and culture. While collaborative innovation makes a firm more efficient in innovation, opportunistic behaviors are caused by information asymmetry among firms, such as the leak of core knowledge from partners to competitors, reducing the efficiency of collaborative innovation and inhibiting the enthusiasm of enterprises to participate in collaborative innovation. Although formal institutions can help alleviate such concerns, they are unlikely to eliminate it. Williamson pointed out that without the support of the informal system, the formal system is difficult to guarantee collectively optimal outcomes. China is the world′s biggest transition economy with weak legal and governance systems. Thus, informal system may play a more important role.

Based on the analysis conduct above, this paper examines the impact of social capital of informal institutions on corporate collaborative innovation. China is a typical "relational" society, where social capital plays an irreplaceable role in promoting the formation of long-term cooperative relations and ensuring the operation of society. Investigating the impact of social capital on corporate collaborative innovation can better reflect the particularity of the relationship between informal institutions and corporate collaborative innovation in "relational" society. Honesty is the core of social capital. By mitigating the opportunistic behavior of enterprises, social capital has played a role in enhancing the enterprises′ confidence of collaborative innovation. Also, when the company locates in high social capital regions, it is more likely to be recognized by potential partners, because enterprises from the regions featured higher honesty. Therefore, we predict that firms headquartered in regions of high social capital have a higher level of collaborative innovation.

Using the data of World Bank′s 2012 Enterprise Surveys, this paper investigate the impact of social capital on corporate collaborative innovation. We find that social capital has a significant promoting effect on corporate collaborative innovation. Namely, firms with a higher level of social capital have a higher level of collaborative probability and input. This conclusion remains robust after a series of robustness analyses, such as alternative proxy for social capital, instrument variable test and Heckman two-stage sample selection test. This effect is more pronounced in high-tech industries and countries with relatively weak intellectual property protection systems, where opportunistic behaviors is more serious. We also find that this effect is only pronounced in firms with low-innovation ability or low-financing constraints. The result indicates that the social capital play an important role in reducing the opportunistic behavior of enterprises and promoting collaborative innovation among firms, and the role is more pronounced where the formal system is not perfect.

This study contributes to the literature in many aspects. First, we contribute to the literature on the determinants of firms′ collaborative innovation activities. Existing studies propose the drivers of collaborative innovation activities as legal environment, government regulation and industrial policy. However, most of the studies emphasize the role of formal system and little attention concerns about informal systems. Under the background of imperfect formal system, the influence of informal system on collaborative innovation cannot be ignored. Here, we complement those studies by analyzing whether social capital influence corporate collaborative innovation. Second, our work contributes to a growing literature on the relationship between social capital and corporate or regional innovation capabilities. Studies in this stream of research have focused on the relationship between corporate and regional innovation. By supplementing internal innovation with systematic scanning for external knowledge, collaborative innovation can improve a firm′s innovative capabilities. In this way, we deepen the relationship between social capital and technological innovation. Finally, our study provides important policy implications by identifying the profound impact of social capital on corporate collaborative innovation. Innovation is the fundamental way to enhance our innovation capability and national competitiveness. Therefore, policy makers should pay attention to the role of informal systems, such as social capital, so as to better enhance national competitiveness.