Semiconductor Lead Frame Manufacturing with Notched Bent Portions
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Solution Overview
Problem
Conventional semiconductor device manufacturing methods are costly and prone to reliability issues due to thermal stress at the joint between the lead frame and substrate, requiring multiple processes that increase production expenses and reduce connection reliability.
Innovation Solution
A method involving selective punching and bending of metal plates to form lead frames with bent portions and notch areas, where conductive bonding material is used to secure the lead frames to the substrate, reducing manufacturing steps and ensuring a consistent bonding thickness, thus alleviating stress and enhancing joint reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coining process is applied to ensure solder material thickness at the lead frame joint, then the bonding reliability is improved, but the manufacturing cost and process complexity increase due to requiring four separate processes
Solution Approach 1:
The invention combines the coining function into the punching process by designing the punching die with a coining portion that protrudes into the punching cavity. This integration allows the lead frame tip to be both punched and coined in a single operation, eliminating the need for separate coining and bending processes while ensuring adequate solder material thickness at the joint.
Solution Approach 2:
The coining action is performed preliminarily during the punching process itself, before the actual bonding operation. The punching die's coining portion pre-deforms the lead frame tip to create the necessary thickness and shape for reliable solder bonding, preparing the joint in advance for the bonding step.
2Manufacturing precision
If multiple manufacturing processes are used to form the lead frame, then the joint structure is optimized, but the manufacturing cost increases
Solution Approach 1:
The invention merges multiple functions (punching, coining, and bending) into a single punching process by designing the punching die with integrated features. The die includes a coining portion that protrudes into the cavity and a bending portion that forms the lead frame tip at an angle, allowing all operations to be completed in one step while maintaining precise joint structure.
Solution Approach 2:
The punching die is designed as a multi-functional tool that simultaneously performs punching, coining, and bending operations. This universal tool eliminates the need for multiple specialized processes, reducing manufacturing cost while achieving the required joint precision through the integrated design features.
3Device complexity
If the lead frame tip is directly bonded without bending, then the manufacturing process is simplified, but thermal stress reliability deteriorates due to insufficient bonding material thickness
Solution Approach 1:
The invention combines the bending operation with the punching process by incorporating a bending portion in the punching die. This integrated approach creates the necessary lead frame tip angle and thickness for reliable thermal stress resistance without requiring a separate bending process, maintaining process simplicity while improving reliability.
Solution Approach 2:
The lead frame tip is preliminarily bent and shaped during the punching operation itself, creating the optimal geometry for stress distribution and bonding material retention before the bonding step occurs. This preliminary formation ensures adequate solder material thickness is present before bonding begins.
Data Source
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AI summary
In a first step of a method of manufacturing a semiconductor device, a portion to be the first lead frame is formed by selectively punching a metal plate, furthermore, notch portions depressed in the reference direction are formed on both side surfaces of a portion, of the first lead frame where the first bent portion is formed, in line contact with the first conductive layer in the reference direction; in the second step of the method, a first bent portion is formed by bending the one end of the first lead frame so as to protrude downward along the reference direction; and in the third step of the method, the upper surface of the first conductive layer and the lower surface of the first bent portion of the first lead frame are joined at the end of the substrate, by the first conductive bonding material, furthermore, the upper surface of the first conductive layer and the notch portions of the first bent portion are joined, by embedding a part of the first conductive bonding material in the notch portions.