Variable-Width Conductive Pattern for Ceramic Package Stress Relief
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Solution Overview
Problem
In electronic devices with ceramic packages, the difference in thermal expansion coefficients between the ceramic package, support units, and metal wires leads to stress and reduced connection strength at the interface, potentially causing the support unit to peel off due to temperature changes.
Innovation Solution
The electronic device incorporates a conductive pattern with a narrow width portion between the attaching portions of the support unit and the ceramic package, which reduces stress caused by thermal expansion differences, and includes broad width portions on either side of the narrow width portion to absorb stress efficiently, thereby maintaining connection strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a support unit with metal wires is connected to a ceramic package using adhesive, then the electronic device can be assembled, but stress occurs in the connection portion due to thermal expansion differences, reducing connection strength
Solution Approach 1:
The conductive pattern's width is changed along its length, creating a variable cross-section structure. The width transitions from a first width at the first attaching portion to a second width at the second attaching portion, with an intermediate width in between. This parameter change allows the conductive pattern to accommodate thermal expansion differences while maintaining connection strength.
Solution Approach 2:
Different portions of the conductive pattern are given different width characteristics. The first attaching portion has a larger width to provide strong mechanical bonding, the second attaching portion has a different width configuration, and the intermediate portion has a transitional width. This local quality differentiation optimizes both connection strength and stress distribution.
2Stability of the object's composition
If the support unit is rigidly connected to the ceramic package, then structural stability is improved, but stress concentration occurs at the connection portion due to thermal expansion differences
Solution Approach 1:
The conductive pattern employs a variable width parameter along its length, creating a gradient structure that transitions from wider sections at the attaching portions to a narrower intermediate section. This parameter variation provides structural stability at the connection points while reducing stress concentration in the intermediate region through the tapered geometry.
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 configuration effectively suppresses the reduction in connection strength between the support unit and the ceramic package, enhancing the reliability of the electronic device by mitigating stress from thermal changes.
Implementation Method 1
a coefficient of thermal expansion (coefficient of linear thermal expansion) differs between the ceramic package serving as the base and the support unit connected (fixed) to the ceramic package
Data Source
AI summary
An electronic device includes: a base; a support unit that includes first and second attaching portions disposed to be separated from each other in a first direction via a middle portion having a conductive pattern formed from a conductive member and is attached to the base in the first and second attaching portions; and a functional element that is supported by the support unit. The conductive pattern includes a broad width portion having a width W1 in a second direction orthogonal to the first direction and a narrow width portion having a width W2 narrower than the width W1 in a plan view.