Anodic Bonding of Glass Sealing Cap to Silicon Substrate

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Solution Overview

Problem

Current technologies lack a reliable method for hermetically sealing electronic parts on silicon substrates with through electrodes, which are essential for high-density packaging and high-speed applications, while also ensuring moisture and thermal stress protection.

Innovation Solution

A silicon circuit substrate with through electrodes is used, where the electronic parts are mounted and hermetically sealed within a sealing cap featuring a ring-shaped protruded bonding portion made of glass, anodically bonded to the substrate, allowing for high-density wiring and effective sealing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a sealing cap is provided on a silicon substrate having through electrodes, then high-density packaging and high-speed applications are enabled, but reliable hermetic sealing method is not established

Engineering Contradiction:

Improvepackaging densityVSAvoidhermetic sealing reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The sealing cap is divided into a body portion and a separate ring-shaped protruded bonding portion made of glass. This segmentation allows the bonding portion to be specifically optimized for hermetic sealing with the silicon substrate while the body portion provides the sealing cavity, resolving the contradiction by enabling reliable sealing through specialized material selection in the bonding region.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sealing cap uses a composite structure combining glass material in the protruded bonding portion with the main cap body. The glass material provides excellent hermetic sealing properties and thermal matching with silicon, while the overall structure maintains the required sealing functionality, thus achieving both high packaging density and reliable hermetic sealing.

Inventive Principle:

Principle #40Composite materials

2Productivity

If through electrodes are provided in silicon substrate, then wiring layers on both sides are connected enabling high-density packaging, but moisture intrusion and thermal stress protection becomes difficult

Engineering Contradiction:

Improvewiring densityVSAvoidmoisture intrusion and thermal stress

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The harmful effects of moisture and thermal stress are addressed by extracting and isolating the through electrode regions from environmental exposure. The sealing cap with its hermetic sealing capability encloses the electronic parts, effectively removing them from contact with moisture and temperature variations, while the through electrodes maintain their electrical connectivity function.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The sealing cap creates an inert, protected environment around the electronic parts mounted on the silicon substrate. This enclosed space isolates the sensitive components and through electrode regions from harmful external factors such as moisture and thermal stress, allowing high-density wiring configurations without compromising reliability.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

3Reliability

If glass cap is bonded to sensor chip, then hermetic sealing is achieved, but space for swinging of weighting portion must be ensured requiring recessed portion

Engineering Contradiction:

Improvehermetic sealingVSAvoidcavity space configuration

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

Instead of creating a recessed portion in the sealing cap to accommodate the weighting portion's swinging space, the invention utilizes the three-dimensional space above the silicon substrate in a different dimension. The protruded bonding portion extends toward the electronic parts, allowing the weighting portion to swing in the available space without requiring modifications to the sealing cap structure, thus maintaining hermetic sealing while providing necessary movement space.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 the reliability of electronic parts by reducing moisture intrusion and thermal stresses, enabling high-speed and high-density packaging with improved thermal matching between the silicon chip and interposer.

Implementation Method 1

the protruded bonding portion (glass) of the sealing cap, in which the ring-shaped protruded bonding portion and the cavity are provided, is anodically bonded to the bonding portion of the silicon circuit substrate

Methodology Applied

Scientific EffectAnodic bonding: Anodising

Data Source

PatentUS7656023B2Electronic parts packaging structure and method of manufacturing the same

Publication Date: 2010.02.02 SHINKO ELECTRIC IND CO LTD

AI summary

In an electronic parts packaging structure of the present invention, an electronic parts is mounted or formed on a silicon circuit substrate having a structure in which wiring layers on both sides thereof are connected to each other through a through electrode, and a protruded bonding portion which is ring-shaped and is made of glass, of a seal cap having a structure in which a cavity is constituted by the protruded bonding portion, is anodically bonded to a bonding portion of the silicon circuit substrate, thus, the electronic parts is hermetically sealed in the cavity of the sealing cap.