Microstructure Sealing Tool Using Embedded Heater

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Solution Overview

Problem

Temperature-sensitive microelectromechanical devices, such as micromirror array devices, face degradation during packaging due to improper heat application, which can alter mechanical properties and cause thermal activation of particles, leading to diffusion and degradation.

Innovation Solution

A packaging method using an embedded heater to produce localized heat for solder melting, combined with an external heater to maintain the package lid at a uniform temperature, and a heat exchanger to control the temperature gradient, ensuring the electronic device remains within a tolerable temperature range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If heat is applied to melt solder material for bonding substrates, then bonding reliability is improved, but temperature-sensitive microstructures may be degraded due to excessive heat

Engineering Contradiction:

Improvebonding reliabilityVSAvoidheat-induced degradation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies heat locally at the bonding interface between substrates using an embedded heater, rather than heating the entire package uniformly. This localized heating melts the solder material at the bonding zone while keeping the temperature-sensitive microstructures in other areas below their degradation threshold, thus resolving the contradiction between achieving reliable bonding and preventing heat-induced damage.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the temperature parameter distribution within the package by using an embedded heater to create a temperature gradient. The bonding interface reaches the solder melting temperature (e.g., 180-250°C) while the microstructure areas are maintained at lower temperatures (e.g., below 150°C), allowing bonding to proceed without degrading the microstructures.

Inventive Principle:

Principle #35Parameter changes

2Strength

If uniform heat is applied to the package lid to prevent cracking, then mechanical integrity is improved, but heat may diffuse to the electronic device causing thermal activation of particles

Engineering Contradiction:

Improvemechanical integrityVSAvoidthermal activation of particles

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a temperature gradient as an intermediary mechanism between the heat source and the electronic device. The embedded heater creates controlled heat diffusion paths, allowing the package lid to be maintained at a uniform temperature for mechanical integrity while the temperature-sensitive regions are protected by being positioned in cooler zones of the thermal gradient.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If high temperature is used for solder bonding, then bonding strength is improved, but microstructure mechanical properties may be altered

Engineering Contradiction:

Improvebonding strengthVSAvoidmicrostructure mechanical properties

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

The patent segments the heating function into two independent components: an embedded heater for localized solder melting and an external heater for uniform package lid heating. This segmentation allows independent control of temperature at the bonding interface versus the overall package temperature, enabling strong bonding while preserving microstructure mechanical properties by preventing excessive heat exposure.

Inventive Principle:

Principle #1Segmentation

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 method provides reliable and robust packaging for temperature-sensitive devices by preventing damage from heat-induced degradation, maintaining mechanical integrity, and ensuring effective bonding without cracking or deformation.

Implementation Method 1

an embedded heater in the package substrate is used to produce localized heat for melting the solder material

Methodology Applied

Scientific EffectResistive heating: Joule Heating

Implementation Method 2

an external heater is used to maintain the package lid at a uniform temperature higher than the melting temperature of the solder material

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

a heat exchanger, preferably at a temperature lower than the temperature of the external heater or the embedded heater is attached to the package substrate. With the heat exchanger, a temperature gradient can be produced from the package lid to the heat exchanger, with which, heat produced in the package during the packaging process can be ducted to the heat exchanger and released outside the package

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Data Source

PatentUS7655553B2Microstructure sealing tool and methods of using the same

Publication Date: 2010.02.02 TEXAS INSTRUMENTS INC

AI summary

A method of packing electronic devices and an apparatus thereof are disclosed herein. The method allows for usage of solder materials with a melting temperature of 180° C. or higher, such as from 210° C. to 300° C., and from 230° C. to 260° C., so as to provide reliable and robust packaging. This method is particularly useful for packaging electronic devices that are sensitive to temperatures, such as microstructures, which can be microelectromechanical devices (MEMS), such as micromirror array devices.