Tall Solder Columns for Through-Mold Interconnects

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current surface mount technology struggles to meet the top-side ball attach height requirements for through-mold interconnects, especially in worst-case scenarios, due to limitations in solder ball height, which affects the reliability of package-on-package assembly in miniaturized electronics.

Innovation Solution

The development of techniques to create taller solder balls by controlling the height of solder columns using processes such as inkjet printing of flux and solder, and reflowing within laser-ablated openings in the molding, allowing for heights between 220 and 320 micrometers to ensure reliable electrical connections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If conventional solder ball formation processes are used, then manufacturing simplicity is maintained, but solder ball height is insufficient to meet top-side ball attach requirements

Engineering Contradiction:

Improvesolder ball heightVSAvoidprocess complexity

Core Design Contradiction:

Length of moving objectVSDevice complexity

Solution Approach 1:

The solder ball formation process is divided into multiple stages: initial solder deposition, molding, opening formation, and additional solder formation. This segmentation allows each stage to be optimized independently, achieving the required 220-320 micrometer height while managing process complexity through systematic breakdown of the formation process.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Solder is deposited in advance during the molding process, and openings are formed in the molding before final solder ball completion. This preliminary action ensures that the substrate and molding are prepared beforehand, allowing the solder to be formed to the exact required height without requiring post-assembly adjustments.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If solder ball height is increased to meet worst-case scenarios, then reliability of electrical connections is improved, but risk of solder bridging increases

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidsolder bridging risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The molding material has different properties in different regions: it provides mechanical support in bulk but creates localized openings with precise dimensions. These openings are strategically positioned and sized to allow solder balls to achieve the required 220-320 micrometer height while maintaining separation between adjacent solder balls, thus preventing bridging while ensuring connection reliability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The molding acts as an intermediary structure that both supports the solder balls and prevents them from bridging. The openings in the molding serve as controlled environments where solder balls can grow to the necessary height while the molding material itself physically separates adjacent solder balls, eliminating the harmful bridging effect.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Area of moving object

If miniaturization is pursued to reduce package size, then device dimensions are reduced, but interconnection complexity increases

Engineering Contradiction:

Improvepackage areaVSAvoidinterconnection complexity

Core Design Contradiction:

Area of moving objectVSDevice complexity

Solution Approach 1:

The solder balls are nested within openings in the molding, which itself is nested over the substrate. This nested structure allows the interconnection elements (solder balls) to be contained within the package footprint rather than extending outward, enabling miniaturization while maintaining the required 220-320 micrometer solder ball height for reliable connections.

Inventive Principle:

Principle #7Nested doll (Nesting)

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 approach enables the creation of taller solder balls that can consistently meet both best and worst-case height targets, enhancing the reliability of electrical connections and assembly processes in miniaturized electronics, while minimizing the risk of solder bridging.

Implementation Method 1

laser-ablated openings in the molding

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

reflowing within laser-ablated openings

Methodology Applied

Scientific EffectReflow heating: Heating

Data Source

PatentUS9159690B2Tall solders for through-mold interconnect

Publication Date: 2015.10.13 INTEL CORP

AI summary

Generally discussed herein are systems and apparatuses that include an extended TSBA ball and techniques for making the same. A package can include a chip package situated below a lower surface of a first substrate, the package including a die situated on a top surface of a second substrate, a molding disposed over the upper surface of the second substrate, the molding extending over the second die and including an opening extending from an upper surface of the molding towards an upper surface of the second substrate, wherein the opening is configured to admit at least a portion of the solder ball, and a solder column electrically and mechanically coupled to the second substrate, situated in the opening, conforming to the cylinder, and including at least two layers of solder with flux therebetween.