Semiconductor Memory Device Lead Frame Extension Design
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Solution Overview
Problem
The cost reduction in manufacturing semiconductor memory devices is hindered by the large installation area occupied by semiconductor memory chips on organic substrates, which restricts the effectiveness of using cheaper materials for the wiring substrate.
Innovation Solution
The semiconductor memory device design features an organic substrate with a non-overlapping shape, a lead frame with extensions to the resin mold, and a resin mold that seals the components, allowing for efficient use of less expensive materials and reducing the area occupied by the organic substrate, thereby enhancing adhesive strength and manufacturing yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If semiconductor memory chips are mounted on an organic substrate to form a semiconductor memory device, then the device can be manufactured with external terminals and sealed structure, but the installation area occupies a large area which restricts cost reduction
Solution Approach 1:
The organic substrate is divided into two distinct regions: a first area for mounting semiconductor memory chips and a second area for bonding to the lead frame. This segmentation allows each region to be optimized for its specific function, reducing the overall substrate area while maintaining device functionality.
Solution Approach 2:
The patent transitions from a conventional layout where the organic substrate fully covers the chip installation area to a design where the substrate is reduced to specific functional areas. The lead frame extensions provide additional structural support in the reduced substrate areas, effectively distributing functions across different dimensional spaces.
2Ease of manufacture
If the organic substrate area is reduced to lower manufacturing costs, then cost reduction is achieved, but the holding power of the lead frame during resin molding may be insufficient
Solution Approach 1:
The lead frame is designed with extensions that protrude from the resin mold before molding occurs. These extensions are prepared in advance to provide bonding surfaces that will engage with the reduced organic substrate areas, ensuring adequate holding power is established before the molding process begins.
Solution Approach 2:
The lead frame extensions are strategically positioned to bond with specific local areas of the organic substrate (the second area). This localized bonding approach concentrates the holding force where needed most, compensating for the overall reduction in substrate area while maintaining adequate strength during resin molding.
Data Source
AI summary
According to one embodiment, a semiconductor memory device including an organic substrate with an external connection terminal and a semiconductor memory chip. The semiconductor memory device further includes a lead frame having a bonded portion and an installation portion. It further includes a resin mold for sealing the semiconductor memory chip. The lead frame is provided with a plurality of extensions at least from one of the installation portion and the bonded portion, in a way of extending at least to two or more sides of the resin mold.