Leadless IC Package with Bottom-Exposed Contacts
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Solution Overview
Problem
Conventional IC packages with external leads occupy more space, limit pin count, and require additional inspection steps due to their linear arrangement, which affects electrical performance and is problematic in systems with limited PCB space.
Innovation Solution
The development of leadless IC packages where electrical contacts are covered on top but exposed on the bottom, allowing for connections beneath the package, and various manufacturing methods such as flip-chip configurations and etching techniques are used to define these contacts, eliminating the need for external leads and reducing package size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external leads are used in IC packages, then electrical connections can be formed with PCB, but the package size increases and PCB space is consumed
Solution Approach 1:
The patent transitions from a two-dimensional lead arrangement (extending horizontally from package sides) to a three-dimensional configuration where electrical contacts are embedded within the package body and extend vertically through the molding material to the bottom surface. This dimensional change allows electrical connections without occupying additional PCB footprint space.
Solution Approach 2:
The electrical contacts are nested within the package structure, embedded in the molding material rather than extending externally. The contacts are contained within the package body like a doll within a doll, eliminating the need for external lead extensions that consume PCB space.
2Reliability
If external leads are arranged along the sides of IC packages, then electrical connections can be made, but the pin count is limited by the linear distance around the package
Solution Approach 1:
The patent moves electrical contacts from a one-dimensional arrangement (along the perimeter of package sides) to a two-dimensional array on the bottom surface. This allows multiple contacts to be arranged in a grid pattern rather than being constrained to a linear path around the package.
Solution Approach 2:
Multiple electrical contacts are combined into a single plane (bottom surface) rather than being distributed along multiple sides. This consolidation into a two-dimensional array increases the effective pin count by utilizing surface area rather than perimeter length.
3Reliability
If external leads are used, then electrical connections can be formed, but additional inspection steps are required for straightness, coplanarity, and mechanical dimensions
Solution Approach 1:
The patent extracts the problematic external lead structure and replaces it with embedded electrical contacts. By removing the external portion of the contacts and embedding them within the molding material, the inspection requirements for lead straightness, coplanarity, and mechanical dimensions are eliminated.
Solution Approach 2:
Instead of using traditional external leads that require complex inspection, the patent uses a simplified contact structure embedded in the package. The electrical connection function is copied through alternative means (embedded contacts rather than external leads), reducing inspection complexity.
Data Source
AI summary
A leadless integrated circuit (IC) package comprising an IC chip mounted to a die-attach area and a plurality of electrical contacts electrically connected to the IC chip. The IC chip, the electrical contacts, and the die-attach area are all covered with a molding material, with portions of the electrical contacts and die-attach area protruding from a bottom surface of the molding material.