Flippable Leadframe Assembly for Stacked Chip Alignment

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Solution Overview

Problem

Conventional semiconductor manufacturing faces challenges with excessive manual handling and difficult alignments when using two separate leadframes for high-density stacking, especially when integrating passive components close to active chips, leading to misalignment and solder reflow limitations.

Innovation Solution

A single leadframe is constructed with a first sub-leadframe connected by links to a second sub-leadframe, allowing the second sub-leadframe to be rotated and aligned effortlessly, using bendable necks as rotation pivots, and encapsulated with insulating material, enabling efficient integration of passive components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If two separate leadframes are used for high-density stacking, then the number of inputs/outputs and freedom of choosing chips of different sizes are improved, but manual handling complexity and alignment difficulty increase

Engineering Contradiction:

Improvenumber of inputs/outputsVSAvoidmanual handling complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines two separate leadframes into a single integrated leadframe structure that includes both a first leadframe and a second leadframe. This merging maintains the versatility of having multiple inputs/outputs and support for different chip sizes while eliminating the manual handling complexity of aligning two separate leadframes, as they are pre-integrated into one piece.

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If two separate leadframes are used for high-density stacking, then freedom of choosing chips of different sizes is improved, but alignment precision and coplanarity control deteriorate

Engineering Contradiction:

Improvefreedom of choosing chips of different sizesVSAvoidalignment precision

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

By integrating both leadframes into a single leadframe structure with pre-defined geometric relationships, the patent eliminates alignment precision issues between separate leadframes. The first and second leadframes are manufactured as one piece, ensuring precise coplanarity and relative positioning while still allowing accommodation of chips with different sizes through the versatile leadframe design.

Inventive Principle:

Principle #5Merging (Combining)

3Area of stationary object

If passive components are integrated close to active chips, then package area is reduced, but misalignment risk and solder reflow limitations increase

Engineering Contradiction:

Improvepackage areaVSAvoidalignment precision

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The integrated leadframe structure combines active chips and passive components into a single unified assembly. The first and second leadframes are pre-aligned and encapsulated together, allowing passive components to be placed close to active chips without introducing misalignment risks. The single leadframe structure ensures precise relative positioning of all components while maintaining compact package area.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS11742263B2Flippable leadframe for packaged electronic system having vertically stacked chip and components

Publication Date: 2023.08.29 TEXAS INSTRUMENTS INC

AI summary

A leadframe for electronic systems comprising a first sub-leadframe connected by links to a second sub-leadframe, the first and second sub-leadframe connected by tiebars to a frame; and each link having a neck suitable for bending the link, the necks arrayed in a line operable as the axis for bending the second sub-leadframe towards the first sub-leadframe with the necks operable as rotation pivots.