Resin-Sealed Semiconductor Package for Solder Thickness Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor devices face issues with thermal deformation due to differing linear expansion coefficients and excess solder overflowing, leading to potential short-circuits and insulation faults, with variations in joining material thickness and overflow regulation being inadequate.
Innovation Solution
A resin-sealed semiconductor device design featuring a second lead frame with protrusions and grooves to regulate joining material thickness and inhibit overflow, using mold resin to seal and control stress, with grooves along the periphery to manage solder flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the size of the lead frame is enlarged to apply large current, then the current capacity is improved, but the thermal deformation force increases due to difference among linear expansion coefficients
Solution Approach 1:
A stress relief structure consisting of a groove and protrusion is introduced as an intermediary element between the lead frame and the semiconductor element. The groove is formed in the lead frame, and the protrusion is formed in the joining material, creating a mechanical feature that absorbs and relieves thermal deformation stress while maintaining the enlarged lead frame size needed for high current capacity.
2Reliability
If a groove is provided to inhibit solder wetting and spreading, then the reliability is improved by preventing short-circuit, but the manufacturing precision deteriorates due to variations in joining material thickness
Solution Approach 1:
The groove is preliminarily formed in the lead frame before the joining material is applied. This pre-formed groove structure guides and regulates the flow of joining material during the joining process, ensuring that the joining material fills the groove completely while preventing excessive overflow. This preliminary structural preparation enables both reliable solder containment and consistent joining material thickness.
3Object-generated harmful factors
If the groove is provided to regulate solder overflow, then the harmful factors are reduced by preventing solder spreading, but the joining material thickness control becomes inadequate
Solution Approach 1:
The protrusion in the joining material acts as an intermediary regulatory element that works in conjunction with the groove in the lead frame. The protrusion protrudes from the joining material into the groove, creating a mechanical stop that precisely controls the thickness of the joining material layer while containing the solder overflow. This dual-structure intermediary system simultaneously achieves both solder containment and thickness regulation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design effectively regulates joining material thickness, inhibits solder overflow, and reduces stress on semiconductor elements, ensuring high-quality, reduced-size devices at lower costs.
Implementation Method 1
mold resin sealing the first lead frame, the second lead frame, the semiconductor element, and the heat spreader together, such that a part of the first lead frame and a part of the second lead frame are exposed
Data Source
AI summary
Provided is a resin-sealed semiconductor device that can regulate the thickness of a joining material joining a semiconductor element and a lead frame and inhibit the joining material from leaking out of a proper range. The resin-sealed semiconductor device includes a second lead frame joined via a second joining material above a semiconductor element joined above a heat spreader. The second lead frame has, on a surface thereof opposed to the semiconductor element, a protrusion to regulate a thickness of the second joining material, and a groove formed at a peripheral part of the second joining material.