Semiconductor Package Inner Outer Leads Vertical Spacing

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Solution Overview

Problem

Semiconductor die packages face limitations in increasing the number of external connectors due to the limited number of lead fingers, which restricts the accommodation of increased functionality and power supply rail requirements, while maintaining a small footprint.

Innovation Solution

The semiconductor die package design includes a lead frame with both outer and inner leads extending outside the packaging compound, allowing for surface mounting, where outer leads have external connection sections and inner leads have downset external connection sections spaced from bonding sections, with a non-electrically conductive die mount and mold compound housing for encapsulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the number of lead fingers is increased to accommodate more external connectors, then the connectivity and functionality are improved, but the package footprint increases

Engineering Contradiction:

Improvenumber of external connectorsVSAvoidpackage footprint

Core Design Contradiction:

Quantity of substanceVSArea of stationary object

Solution Approach 1:

The patent introduces a two-layer lead finger structure with outer leads and inner leads at different vertical levels. The inner leads extend through openings in the mold compound to provide connection points beneath the package, effectively utilizing the vertical dimension to increase connector density without expanding the horizontal footprint.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The inner leads are positioned within the area defined by the outer leads, creating a nested configuration where inner leads extend through openings in the mold compound to provide additional connection points. This nested arrangement maximizes the use of available space within the package footprint.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Adaptability or versatility

If lead fingers extend outside the mold compound for surface mounting, then surface mountability is improved, but the structural complexity increases

Engineering Contradiction:

Improvesurface mountabilityVSAvoidlead frame structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The lead frame is segmented into distinct outer leads and inner leads with different functions and configurations. Outer leads extend for through-hole mounting while inner leads extend through mold compound openings for surface mounting, allowing the structure to accommodate multiple mounting methods without requiring a completely separate design for each.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8853840B2Semiconductor package with inner and outer leads

Publication Date: 2014.10.07 NXP USA INC

AI summary

A semiconductor die has outer leads with an outer lead external connection section and an outer lead bonding section. Inner leads are spaced from the outer leads. Each of the inner leads has an inner lead external connection section spaced and downset from an inner lead bonding section. A non-electrically conductive die mount is molded onto upper surface areas of each inner lead external connection section. A semiconductor die is mounted on the non-electrically conductive die mount and bond wire provide interconnects for selectively electrically connecting bonding pads of the die to the inner lead bonding sections and at least one outer lead bonding section. A mold compound covers the semiconductor die, the bond wires, and the outer and inner lead bonding sections.