Lead Frame Ring Portion Prevents Creep in Semiconductor Molding
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Solution Overview
Problem
The existing methods for manufacturing semiconductor devices face challenges in preventing the creep phenomenon during screwing due to unevenness or inclination of the molding resin, which increases manufacturing costs, and require precise dimensional accuracy of dies and lead frames to avoid resin burrs or cracks.
Innovation Solution
A method involving a lead frame with a ring portion that is embedded within the molding resin, ensuring uniform contact and distributing axial forces evenly, thereby preventing creep and reducing manufacturing costs by eliminating the need for additional collars and precise die dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a collar is inserted into the mounting hole to prevent creep phenomenon, then the reliability of fastening is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the collar function with the lead frame by forming an integrated structure where the lead frame itself serves as the fastening component. The lead frame includes a mounting portion with a through-hole that receives the screw, eliminating the need for a separate collar while maintaining the ability to prevent creep phenomenon through proper structural design
Solution Approach 2:
The lead frame is designed to perform multiple functions: electrical connection, mechanical support, and fastening. The mounting portion of the lead frame serves both as an electrical lead and as a structural element for screw fastening, reducing the total number of components needed while maintaining fastening reliability
2Manufacturing precision
If the dimension between upper die and lower die is increased to avoid compressing the lead frame, then the manufacturing precision is improved, but resin burrs are generated and manufacturing cost increases
Solution Approach 1:
The patent performs preliminary positioning by forming the lead frame with precise dimensions before resin molding. The lead frame serves as a pre-formed precision component that defines the exact spacing required, allowing the resin molding process to proceed without requiring extremely precise die dimensions while avoiding burr formation
3Device complexity
If the dimension between upper die and lower die is decreased to expose lead frame portions, then the device complexity is reduced, but the lead frame is compressed during molding causing residual stress and potential cracks
Solution Approach 1:
The lead frame is pre-formed with the exact dimensions and shape required before resin molding. This preliminary formation ensures that the lead frame has sufficient strength and proper geometry, allowing it to withstand the molding process without compression-induced stress or cracking while maintaining structural simplicity
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 method effectively prevents creep and reduces manufacturing costs by ensuring uniform pressure distribution and eliminating the need for precise die alignment, while maintaining the structural integrity of the semiconductor device.
Implementation Method 1
injecting a molding resin in a liquid form into the cavity and curing the molding resin
Data Source
AI summary
A method for manufacturing a semiconductor device includes steps (a) to (e). In the step (a), a lead frame including a plurality of lead portions, tie bars, a frame body, and ring portions is prepared. In the step (b), an assembled body is formed. In the step (c), the assembled body is placed in a cavity. In the step (d), a molding resin in a liquid form is injected into the cavity and cured in a state in which a pin is inserted through a hole of the ring portion and an upper surface of the ring portion is in contact with an inner surface of the upper die, and a resin-molded body is formed. In the step (e), the frame body, the tie bars, and connecting portions are cut after the resin-molded body is taken out from the molding die.