Interposer Cuts Enable Vertical Contact Flex

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Solution Overview

Problem

Conventional test systems face challenges in achieving good electrical contact between integrated circuits and interposers due to fine pitch and large number of metal contacts, often requiring expensive load-boards with complex elastomer structures that may not provide sufficient current carrying capacity and planarity.

Innovation Solution

An interposer with cuts through an insulating substrate allows metal contacts on both sides to flex vertically, facilitating electrical contact with the load-board and contactor pins, and using multiple contactor pins per metal contact to reduce contact resistance, while the interposer is made from materials like FR5 or glass epoxy composite.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional load-boards with complex elastomer structures are used to achieve good electrical contact, then electrical contact reliability is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improveelectrical contact reliabilityVSAvoidload-board structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the complex elastomer structure from the load-board entirely. Instead, it uses a simple rigid load-board with protrusions that directly engage with recesses in the interposer, eliminating the need for elastomeric components while maintaining reliable electrical contact.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The interposer is segmented into multiple sections with recesses that correspond to protrusions on the load-board. This segmentation allows for modular assembly and simplifies the overall structure by distributing contact points across multiple discrete engagement features rather than requiring a complex continuous elastomer structure.

Inventive Principle:

Principle #1Segmentation

2Quantity of substance

If fine pitch metal contacts are used to increase contact density, then electrical contact capability is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improvenumber of metal contactsVSAvoidmetal contact alignment precision

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The interposer is pre-formed with recesses that precisely match the protrusions on the load-board before assembly. This preliminary structuring ensures that when the interposer is attached to the load-board, the metal contacts are automatically positioned with high precision, eliminating the need for post-assembly alignment adjustments.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The recesses in the interposer act as an intermediary feature between the load-board protrusions and the fine pitch metal contacts. This intermediary structure provides a mechanical guide that ensures precise alignment of the metal contacts during assembly, making the manufacturing process more tolerant of variations.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Stability of the object's composition

If rigid interposer structures are used to maintain planarity, then structural stability is improved, but adaptability to contact variations decreases

Engineering Contradiction:

Improveinterposer planarityVSAvoidcontact alignment adaptability

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

While the overall interposer structure remains rigid to maintain planarity, the patent incorporates dynamic elements such as spring-loaded contactors that can independently adjust their position. This allows the rigid interposer to maintain its structural stability while the dynamic contactors adapt to variations in contact alignment.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The interposer has different local properties: the bulk structure is rigid to maintain planarity, while specific contact regions have compliant elements or adjustable mechanisms. This local differentiation allows the structure to simultaneously maintain overall stability while providing local adaptability for contact alignment.

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enhances electrical contact reliability, reduces wear on the load-board, and increases its service life by allowing vertical movement of metal contacts and using multiple contactor pins to lower contact resistance.

Implementation Method 1

An interposer with cuts through an insulating substrate allows metal contacts on both sides to flex vertically

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS10962571B2Interposers having cuts through an insulating substrate

Publication Date: 2021.03.30 TEXAS INSTRUMENTS INC

AI summary

An interposer comprises an insulating substrate having a first side and a second side; a first plurality of metal contacts on the first side; a second plurality of metal contacts on the second side; and a plurality of cuts through the insulating substrate. The plurality of cuts comprise a first cut between a first metal contact in the first plurality of metal contacts and a second metal contact in the first plurality of metal contacts, and between a first metal contact in the second plurality of metal contacts and a second metal contact in the second plurality of metal contacts.