Recessed Test Interposer Structure for Crack-Free Solder Ball Testing

Solution Overview

Problem

Conventional testing methods for POP packaging result in internal cracking between solder balls and circuit boards/wafers due to pressure concentration, leading to unstable testing and increased costs.

Innovation Solution

A test interposer modular structure with a recessed concave portion and supporting board design that distributes pressure away from solder balls, preventing direct contact and cracking during electrical testing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the thickness of the interposer is reduced to meet high-speed requirements, then the signal transmission speed is improved, but pressure concentration on solder balls occurs during testing causing internal cracks

Engineering Contradiction:

Improvesignal transmission speedVSAvoidstability of solder joints

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The interposer surface is designed with differentiated local properties: a recessed region with lower hardness (30-50 HRC) directly beneath solder balls to reduce pressure concentration, and a blocking portion with higher hardness (55-65 HRC) at the periphery to prevent solder ball displacement. This local quality differentiation allows the thin interposer to maintain both high-speed performance and solder joint reliability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

A recessed portion is pre-formed in the interposer surface at the solder ball contact locations, creating a cushioning effect before testing begins. This recessed structure (depth 0.05-0.2mm)预先 absorbs and distributes the pressing force during solder ball contact, preventing direct pressure concentration on the solder joints and eliminating internal cracks.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Productivity

If conventional testing methods are used with direct contact between solder balls and interposer, then testing can be performed, but internal cracks occur between solder balls and circuit board/wafer leading to unstable testing

Engineering Contradiction:

Improvetesting efficiencyVSAvoidtesting stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The interposer surface is designed with differentiated local properties: a recessed region with lower hardness (30-50 HRC) directly beneath solder balls to reduce pressure concentration, and a blocking portion with higher hardness (55-65 HRC) at the periphery to prevent solder ball displacement. This local quality differentiation allows the thin interposer to maintain both high-speed performance and solder joint reliability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

A recessed portion is pre-formed in the interposer surface at the solder ball contact locations, creating a cushioning effect before testing begins. This recessed structure (depth 0.05-0.2mm)预先 absorbs and distributes the pressing force during solder ball contact, preventing direct pressure concentration on the solder joints and eliminating internal cracks.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Volume of moving object

If the interposer thickness is reduced, then space is saved and high-speed performance is achieved, but pressure concentration causes cracking between the interposer and solder balls

Engineering Contradiction:

Improveinterposer thicknessVSAvoidresistance to pressure-induced cracking

Core Design Contradiction:

Volume of moving objectVSStrength

Solution Approach 1:

The interposer surface is designed with differentiated local properties: a recessed region with lower hardness (30-50 HRC) directly beneath solder balls to reduce pressure concentration, and a blocking portion with higher hardness (55-65 HRC) at the periphery to prevent solder ball displacement. This local quality differentiation allows the thin interposer to maintain both high-speed performance and solder joint reliability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

A recessed portion is pre-formed in the interposer surface at the solder ball contact locations, creating a cushioning effect before testing begins. This recessed structure (depth 0.05-0.2mm)预先 absorbs and distributes the pressing force during solder ball contact, preventing direct pressure concentration on the solder joints and eliminating internal cracks.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS20260050030A1Test interposer modular structure

Publication Date: 2026.02.19 JGTECHNOLOGYCO LTD

AI summary

The present invention provides a test interposer modular structure applied in a test packaging machine, which includes an upper mold and a lower mold. An interposer is disposed between the upper mold and the lower mold and has an upper top surface recessed toward a lower bottom surface thereof to form a concave portion with a blocking portion on the periphery of the concave portion. When conducting a test, as the upper mold and the lower mold approach each other, the solder balls of an electronic circuit device located between the interposer and the upper mold enter the concave portion, while the portions of the electronic circuit device without the solder balls abut against the blocking portion. This can distribute pressure, preventing internal cracks at the contact points of the solder balls and the interposer, thereby maintaining stability during electrical testing.