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Surface mount technology (SMT) is widely used and plays an important role in electronic equipment. The purpose of this paper is to reveal the effects of interface cracks on the fatigue life of SMT solder joint under service load and to provide some valuable reference information for improving service reliability of SMT packages.

A 3D geometric model of SMT package is established. The mechanical properties of SMT solder joint under thermal cycling load and random vibration load were solved by 3D finite element analysis. The fatigue life of SMT solder joint under different loads can be calculated by using the modified Coffin–Manson model and high-cycle fatigue model.

The results revealed that cracks at different locations and propagation directions have different effect on the fatigue life of the SMT solder joint. From the location of the cracks, Crack 1 has the most significant impact on the thermal fatigue life of the solder joint. Under the same thermal cycling conditions, its life has decreased by 46.98%, followed by Crack 2, Crack 4 and Crack 3. On the other hand, under the same random vibration load, Crack 4 has the most significant impact on the solder joint fatigue life, reducing its life by 81.39%, followed by Crack 1, Crack 3 and Crack 2. From the crack propagation direction, with the increase of crack depth, the thermal fatigue life of the SMT solder joint decreases sharply at first and then continues to decline almost linearly. The random vibration fatigue life of the solder joint decreases continuously with the increase of crack depth. From the crack depth of 0.01 mm to 0.05 mm, the random vibration fatigue life decreases by 86.75%. When the crack width increases, the thermal and random vibration fatigue life of the solder joint decreases almost linearly.

This paper investigates the effects of interface cracks on the fatigue life and provides useful information on the reliability of SMT packages.

The purpose of this paper is to examine evolutionary processes of sectoral systems of innovation in China's catch‐up situation.

History event analysis method is used. The data that inform this paper come primarily from interviews carried out as a part of case studies of the innovations of China's car industry as well as public sources.

Market catch‐up of China's self‐owned brand cars expanded from low to high end market segment. Changes of the five building blocks of innovation system of China's car industry have driven the market catch‐up since the 1980s. The five building blocks are: market demand, industrial technology and knowledge base, institutional setting, industrial structure, firms' competences and strategy. China's car industry evolved through exploitation and exploration, which were affected by the five building blocks. The exploitation and exploration shaped the catch‐up way of China's car industry: from production localization to design localization and self‐owned brands. Exploration of the self‐owned brand group built on exploitation of the joint‐venture group.

The findings are based on a single industry. Studies on more industries are needed to generalize the research results.

Increased understanding of how sectoral systems of innovation evolve will give managers and policy makers in the developing countries like China improved opportunities to formulate policies and management practices that can cultivate innovation capabilities in catch‐up.

The paper contributes to the research stream on sectoral systems of innovation by understanding building blocks and evolutionary processes at the base of change and growth in the catch‐up situation.