Stepped QFP Lead Frame for Increased Contact Density
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Solution Overview
Problem
Conventional quad flat package (QFP) semiconductor devices have limited exposed electrical contacts, which restricts the number of bond zones and increases spacing between contacts and bond wires, hindering the miniaturization and increased complexity of semiconductor devices.
Innovation Solution
The QFP device incorporates an additional row of external exposed terminals by creating a stepped package body, allowing for more bond zones and reducing spacing between contacts and bond wires, enabling increased connectivity without the need for interleaved side leads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional QFP package structure is used, then the device has simple structure and easy manufacturing, but the number of exposed electrical contacts is limited and spacing between contacts is large
Solution Approach 1:
The patent introduces a stepped package body with multiple levels, transitioning from a conventional single-plane contact arrangement to a multi-level three-dimensional structure. The first and second sets of exposed electrical contacts are positioned at different vertical levels on the bottom face of the package body, allowing contacts to be arranged in multiple rows without increasing lateral spacing. This dimensional change enables higher contact density while maintaining a compact footprint.
2Quantity of substance
If the number of exposed electrical contacts is increased, then connectivity is improved, but the spacing between contacts and bond wires increases
Solution Approach 1:
By arranging contacts in multiple rows at different vertical levels on the bottom face, the patent reduces the lateral spacing between adjacent contacts. The stepped structure allows first and second sets of contacts to be positioned in staggered rows, decreasing the horizontal distance between contact points while accommodating a greater total number of contacts within the same package footprint.
3Quantity of substance
If additional rows of contacts are added, then I/O connections are increased, but the package footprint increases
Solution Approach 1:
The stepped package body utilizes the vertical dimension to accommodate additional contact rows without expanding the horizontal footprint. By positioning contact sets at different levels on the bottom face, the design achieves higher I/O connectivity while maintaining a compact package footprint, as the additional contacts are stacked vertically rather than spread laterally.
Data Source
AI summary
A Quad Flat Package (QFP) semiconductor device has a multi-stepped lead frame for forming rows of external contacts. A semiconductor die is attached to a die pad of the lead frame and electrically connected to lead with bond wires. The die and bond wires are encapsulated with a mold compound and then multiple cuts are made to the lead frame to form the rows of external contacts.