OCXO Integrated Circuit Pad Design for Wire Bonding
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Solution Overview
Problem
Existing oven controlled crystal oscillators (OCXO) face challenges in wire bonding productivity due to steps formed by insulating protective films and bonding pads, which can cause capillary collisions and hinder the bonding process.
Innovation Solution
The integrated circuit device design eliminates insulating protective films between adjacent bonding pads, ensuring no steps are formed, and incorporates heat generators and temperature detectors close to the vibrator for efficient heating and temperature control, along with conductive joining materials surrounded by bump members to reduce material spread and improve joining strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating protective film is formed on the diffusion layer and opening portions are formed in the surface protective film to create pads, then the pads are protected and electrically isolated, but steps are formed by the surface protective film and pads which hinder wire bonding
Solution Approach 1:
The insulating protective film is completely removed from the regions where bonding pads will be formed. This extraction eliminates the steps between the protective film and pads, allowing the wire bonding capillary to pass through without collision while maintaining electrical isolation through the substrate structure itself.
2Ease of manufacture
If opening portions are formed in the surface protective film and pads are formed within the opening portions, then wire bonding can be performed on the pads, but the steps formed may cause the capillary to collide with the steps
Solution Approach 1:
The insulating protective film is completely removed from the pad regions before pad formation, eliminating the steps that would cause capillary collision. This allows smooth wire bonding while maintaining the ease of pad formation through direct metal deposition on the substrate.
3Reliability
If conductive joining material is used to join the vibrator to the joining part, then electrical connection is established, but the joining strength may be insufficient
Solution Approach 1:
A composite joining structure is employed combining bump members (metal spheres providing mechanical strength and electrical contact) with conductive joining material (filling gaps and providing additional electrical pathways). This composite approach simultaneously achieves both strong mechanical joining and reliable electrical connection.
Solution Approach 2:
Bump members are formed on the joining part before the actual joining process. These pre-formed bumps provide initial mechanical anchors and electrical contact points, strengthening the joint before the conductive joining material is applied to complete the electrical connection.
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 design enhances wire bonding productivity by preventing capillary collisions, ensuring accurate temperature detection, and improving the joining strength between components, resulting in higher productivity and reliability of the OCXO.
Implementation Method 1
a heat generation IC that includes a semiconductor substrate on which a diffusion layer is formed
Implementation Method 2
crystal oscillators used for reference frequency signal sources
Data Source
AI summary
An integrated circuit device includes a substrate, a joining part provided on the substrate and joined to a vibrator, and a plurality of bonding pads provided on the substrate. The joining part includes an insulating protective film that covers a part of a surface of the substrate, and no insulating protective film is provided between the adjacent bonding pads.