Electronic Device Substrate Bonding Gap Control
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Solution Overview
Problem
In piezoelectric devices, the minute gap between the substrate and the piezoelectric vibrator is not completely filled with mold material, leading to potential short circuits when solder is melted during external substrate mounting.
Innovation Solution
An electronic device design with a substrate having distinct surfaces for different electronic components, where the first electronic component is bonded via solder and the second via a higher-melting-point bonding member, ensuring the mold material does not fill the gap between the components and preventing solder spreading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If solder is used as a spacer to form a minute gap between the substrate and the piezoelectric vibrator, then the bonding strength is improved, but the gap cannot be completely filled with mold material leading to short circuit risk
Solution Approach 1:
The electronic components are divided into two groups: first electronic components (piezoelectric vibrators) that maintain minute gaps for bonding strength, and second electronic components (semiconductor chips) that are completely filled with mold material for reliability. This segmentation allows each group to have optimized gap filling without compromising the other.
Solution Approach 2:
The first electronic components are extracted from the moldable region, creating a non-moldable region where mold material is intentionally excluded. This extraction allows the minute gap around the piezoelectric vibrator to remain unfilled, preserving bonding strength while preventing short circuits.
2Manufacturing precision
If mold material is filled into the minute gap between substrate and piezoelectric vibrator, then the gap filling is improved, but the solder bonding may be melted and spread causing short circuit
Solution Approach 1:
The device is segmented into a moldable region (containing second electronic components) and a non-moldable region (containing first electronic components). This segmentation ensures mold material fills the moldable region completely for manufacturing precision while excluding the non-moldable region to protect solder joint integrity.
Solution Approach 2:
A cap structure serves as an intermediary element that defines the boundary between moldable and non-moldable regions. The cap covers the first electronic components to prevent mold material intrusion while allowing mold material to fill the moldable region, thus mediating between the conflicting requirements of gap filling and solder protection.
3Ease of manufacture
If the same bonding method is used for all electronic components, then the manufacturing process is simplified, but the melting point differences cause solder spreading and electrical defects
Solution Approach 1:
Different bonding methods are applied to different regions: the first electronic components use solder bonding with controlled minute gaps, while the second electronic components use mold material bonding with complete gap filling. This local differentiation prevents solder spreading to the second components while maintaining manufacturing feasibility through region-specific processing.
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
Prevents electrical defects like short circuits and increased wiring resistance by ensuring the mold material does not fill the gap between components, maintaining the structural integrity and reliability of the device.
Implementation Method 1
the first electronic component includes a first mounting terminal disposed on a first relative surface relative to the first surface, and is bonded to the first surface on the first relative surface via a conductive first bonding member
Implementation Method 2
the second electronic component includes a second mounting terminal, and is bonded to the second surface via a second bonding member on a second relative surface relative to the second surface, and the second mounting terminal and the second wiring pattern are electrically coupled to each other via a conductive wire
Data Source
AI summary
An electronic device includes: a substrate having an upper surface and a lower surface; a first electronic component mounted on the upper surface of the substrate; a second electronic component mounted on the lower surface of the substrate; and a mold portion covering the second electronic component without covering the first electronic component. The first electronic component is bonded to the upper surface on the first relative surface via a conductive first bonding member. The second electronic component is bonded to the lower surface via a second bonding member on a second relative surface relative to the lower surface.