Flip-Chip Package Encapsulation With LDS Vias for Dual-Sided Cooling

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional semiconductor devices, particularly flip-chip type devices, face reliability issues related to power dissipation due to inadequate thermal dissipation methods.

Innovation Solution

The use of laser-direct-structuring (LDS) technology to mold a die and leadframe with a chromium oxide particle-filled molding compound, creating detectable metal-filled vias and a heat spreader molding compound, facilitates dual-side thermal dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If an exposed pad is used in standard QFN packages to increase thermal dissipation, then thermal dissipation is improved, but reliability issues related to power dissipation occur

Engineering Contradiction:

Improvethermal dissipationVSAvoidreliability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent transitions from single-sided thermal dissipation through the exposed pad to dual-sided thermal dissipation by adding a top thermal pad on the opposite side of the semiconductor die. This dimensional change allows heat to escape in two directions simultaneously, improving thermal management while maintaining reliability.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The thermal dissipation function is segmented into two separate pathways: one through the bottom exposed pad and another through the top thermal pad. This segmentation distributes the thermal load across multiple paths, preventing overheating at any single location and improving overall reliability.

Inventive Principle:

Principle #1Segmentation

2Temperature

If conventional molding methods are used, then manufacturing simplicity is maintained, but thermal dissipation performance is insufficient

Engineering Contradiction:

Improvethermal dissipationVSAvoidmanufacturing simplicity

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The LDS material is pre-integrated into the molding compound before the molding process. This preliminary preparation allows the laser activation and metal deposition steps to be performed after molding, simplifying the overall manufacturing process while enabling advanced thermal dissipation features that would be difficult to achieve with conventional post-molding modifications.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the material parameter of the molding compound by incorporating LDS material with chromium oxide particles. This parameter change enables the material to be activated by laser radiation, creating conductive pathways for thermal dissipation without complicating the molding process itself.

Inventive Principle:

Principle #35Parameter changes

3Temperature

If laser-direct-structuring material is used in molding, then thermal dissipation is enhanced, but manufacturing complexity increases

Engineering Contradiction:

Improvethermal dissipationVSAvoidmanufacturing complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The LDS material serves multiple functions: it provides thermal dissipation pathways, enables electrical conductivity in the molding compound, and creates structurable regions for subsequent laser processing. This multi-functionality reduces the need for separate materials or components, offsetting the increased manufacturing steps with material versatility.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 enhances thermal dissipation in semiconductor devices, improving their performance, especially in power devices where full exploitation of package leads as input/output nodes is desirable.

Implementation Method 1

applying laser direct structuring processing to the LDS material of the encapsulation to provide at least one metal via between the outer surface of the encapsulation and the second side of the at least one semiconductor chip or die

Methodology Applied

Scientific EffectLaser activation: Laser

Implementation Method 2

a heat spreader molding compound (with chromium oxide particles)

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS12211763B2Enhanced thermal dissipation in flip-chip semiconductor devices using laser direct structuring (LDS) technology

Publication Date: 2025.01.28 STMICROELECTRONICS SRL

AI summary

A method of manufacturing semiconductor devices, such as QFN/BGA flip-chip type packages, arranging on a leadframe one or more semiconductor chips or dice having a first side facing towards the leadframe and electrically coupled therewith and a second side facing away from the leadframe. The method also includes molding an encapsulation on the semiconductor chip(s) arranged on the leadframe, where the encapsulation has an outer surface opposite the leadframe and comprises laser direct structuring (LDS) material. Laser direct structuring processing is applied to the LDS material of the encapsulation to provide metal vias between the outer surface of the encapsulation and the second side of the semiconductor chip(s) and as well as a metal pad at the outer surface of the encapsulation.