Warpage Controlled Package Using Shape Memory Alloy Counter Moments

The patent changes the physical state and properties of the substrate material by incorporating shape memory alloys that transition from austenite (high stiffness) to martensite (low stiffness) phases through temperature control. This allows the substrate to dynamically adjust its stiffness parameter without adding external structural elements like glass cloths or frames, resolving the contradiction between maintaining stiffness and reducing structural complexity for thinner packages.

The patent introduces dynamic adaptability to the substrate by using shape memory alloys that can reversibly change their mechanical properties in response to temperature changes. The substrate transitions from a rigid austenitic state during manufacturing to a flexible martensitic state during operation, enabling the package to adapt its stiffness characteristics rather than relying on fixed complex structural reinforcements.

The patent uses temperature-induced phase changes in shape memory alloys to dynamically adjust the substrate's stiffness parameter. During solder reflow at high temperatures, the substrate maintains high stiffness in the austenitic phase to prevent warpage and protect solder joints. After cooling, the substrate transitions to the martensitic phase, becoming more pliable and thinner, thus resolving the contradiction between reduced thickness and maintained connection reliability.

The patent applies preliminary stiffening to the substrate by designing it to be in the austenitic high-stiffness phase during the critical solder reflow process. This preliminary anti-action counteracts the warpage forces that would otherwise occur during heating, preventing stress on solder connections before they are applied, thereby maintaining reliability even in thinner package designs.

The patent exploits the temperature-dependent phase transition of shape memory alloys to change the substrate's stiffness parameter during the solder reflow process. At reflow temperatures, the substrate transforms to the austenitic phase with high stiffness and low thermal expansion, maintaining shape stability. During cooling, it transitions to the martensitic phase with different expansion characteristics, thus resolving the contradiction between achieving strong solder bonds through heating and maintaining substrate shape stability.

The patent utilizes controlled thermal expansion characteristics of shape memory alloys during phase transitions. The austenitic phase exhibits lower thermal expansion coefficients at high temperatures compared to conventional materials, reducing substrate warpage during solder reflow. The material's ability to control its own thermal expansion behavior through phase changes directly addresses the contradiction between heat application for solder strength and shape maintenance.