Encapsulant Cap Surface Roughness for Easier Package Demolding

Solution Overview

Problem

Conventional molded underfill (MUF) processes for semiconductor packages often result in cracks and breakages during demolding due to low interface roughness between the packages and the mold chase, requiring significant force for separation and leading to structural failures.

Innovation Solution

The introduction of an encapsulant cap with a top surface featuring two distinct roughness regions, where the first region has a lower roughness for laser marking and the second region has a higher roughness to facilitate easier demolding, reducing adherence to the mold chase and minimizing cracking risks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the encapsulant cap has a smooth surface (low roughness), then laser marking quality is improved, but demolding becomes difficult causing cracks and breakages

Engineering Contradiction:

Improvelaser marking qualityVSAvoiddemolding ease

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The encapsulant cap is designed with different surface roughness in different regions: a first region with low roughness (0.2-0.8 μm) for high-quality laser marking, and a second region with high roughness (1.5-3.0 μm) for easy demolding. This local differentiation allows each region to optimize its function without compromising the other.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If the encapsulant cap has a rough surface (high roughness), then demolding becomes easier, but laser marking quality deteriorates

Engineering Contradiction:

Improvedemolding easeVSAvoidlaser marking quality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The encapsulant cap is designed with different surface roughness in different regions: a first region with low roughness (0.2-0.8 μm) for high-quality laser marking, and a second region with high roughness (1.5-3.0 μm) for easy demolding. This local differentiation allows each region to optimize its function without compromising the other.

Inventive Principle:

Principle #3Local quality

3Ease of operation

If significant force is applied during demolding, then separation from mold chase is achieved, but cracks and breakages occur

Engineering Contradiction:

Improveseparation capabilityVSAvoidpackage integrity

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The encapsulant cap is designed with different surface roughness in different regions: a first region with low roughness (0.2-0.8 μm) for high-quality laser marking, and a second region with high roughness (1.5-3.0 μm) for easy demolding. This local differentiation allows each region to optimize its function without compromising the other.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The high roughness surface in the second region, which would normally increase adhesion and make demolding difficult, is strategically positioned at the periphery where it actually reduces overall adhesion force by creating air gaps and reducing contact area, thereby facilitating easier demolding without requiring excessive force that could cause cracks.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS20240105538A1Method for making an electronic package

Publication Date: 2024.03.28 JCET STATS CHIPPAC KOREA LTD

AI summary

An electronic package and a method for making an electronic package are provided. The electronic package comprises a substrate; a plurality of electronic components disposed on the substrate; and an encapsulant cap for encapsulating the substrate and the plurality of electronic components, wherein the encapsulant cap comprises a top surface having a first region and a second region; and wherein the first region has a first roughness, the second region has a second roughness greater than the first roughness.