Technical Library | 2017-10-16 15:03:32.0
The miniaturization and advancement of electronic devices have been the driving force of design, research and development, and manufacturing in the electronic industry. However, there are some issues occurred associated with the miniaturization, for examples, warpage and reliability issues. In order to resolve these issues, a lot of research and development have been conducted in the industry and university with the target of moderate melting temperature solder alloys such as m.p. 280°C. These moderate temperature alloys have not resolve these issues yet due to the various limitations. YINCAE has been working on research and development of the materials with lower temperature soldering for higher temperature application. To meet this demand, YINCAE has developed solder joint encapsulant paste to enhance solder joint strength resulting in improving drop and thermal cycling performance to eliminate underfilling, edge bonding or corner bonding process in the board level assembly process. This solder joint encapsulant paste can be used in typical lead-free profile and after reflow the application temperature can be up to over 300C, therefore it also eliminates red glue for double side reflow process. In this paper, we will discuss the reliability such as strength of solder joints, drop test performance and thermal cycling performance using this solder joint encapsulant paste in detail.
Technical Library | 2019-08-07 22:56:45.0
The requirement to reconsider traditional soldering methods is becoming more relevant as the demand for bottom terminated components (QFN/BTC) increases. Thermal pads under said components are designed to enhance the thermal and electrical performance of the component and ultimately allow the component to run more efficiently. Additionally, low voiding is important in decreasing the current path of the circuit to maximize high speed and RF performances. The demand to develop smaller, more reliable, packages has seen voiding requirements decrease below 15 percent and in some instances, below 10 percent.Earlier work has demonstrated the use of micro-fluxed solder preforms as a mechanism to reduce voiding. The current work builds upon these results to focus on developing an engineered approach to void reduction in leadless components (QFN) through increasing understanding of how processing parameters and a use of custom designed micro-fluxed preforms interact. Leveraging the use of a micro-fluxed solder preform in conjunction with low voiding solder paste, stencil design, and application knowhow are critical factors in determining voiding in QFN packages. The study presented seeks to understand the vectors that can contribute to voiding such as PCB pad finish, reflow profile, reflow atmosphere, via configuration, and ultimately solder design.A collaboration between three companies consisting of solder materials supplier, a power semiconductor supplier, and an electronic assembly manufacturer worked together for an in-depth study into the effectiveness of solder preforms at reducing voiding under some of the most prevalent bottom terminated components packages. The effects of factors such as thermal pad size, finish on PCB, preform types, stencil design, reflow profile and atmosphere, have been evaluated using lead-free SAC305 low voiding solder paste and micro-fluxed preforms. Design and manufacturing rules developed from this work will be discussed.
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