Oscillator Package Layout for Uniform Flip-Chip Bonding Pressure
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Solution Overview
Problem
In oscillators with a ceramic package using flip chip bonding, the thickness variation due to external terminal placement leads to uneven pressure distribution during IC mounting, potentially degrading IC performance.
Innovation Solution
The oscillator design includes a package with external terminals and a circuit element where the circuit element's pads do not overlap the external terminals in a plan view, with bump members bonded at positions that avoid overlapping the terminals, ensuring uniform pressure distribution during bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the distance between external terminals is decreased to reduce oscillator size, then the oscillator size is reduced, but the IC pad bonding becomes problematic due to overlapping with external terminals and uneven pressure distribution
Solution Approach 1:
The patent introduces a height dimension (Z-axis) to resolve the planar overlap problem. By forming a raised portion on the package substrate at the external terminal position, the bump member can be positioned at different heights: its bottom surface is bonded to the substrate at a first height, while its top surface is at a second height that does not overlap the external terminal in the height direction. This dimensional separation allows compact layout while maintaining bonding precision.
Solution Approach 2:
The bump member is segmented into distinct functional zones: the bottom surface for bonding to the substrate, the raised portion providing mechanical support and electrical connection, and the top surface for bonding to the IC pad. This segmentation allows each portion to fulfill its specific function without interference from external terminals, resolving the bonding precision issue while maintaining compact size.
2Volume of moving object
If external terminals are placed on the reverse surface to reduce size, then the oscillator size is reduced, but height differences cause uneven pressure distribution during bonding
Solution Approach 1:
The raised portion creates an equipotential surface for bonding by elevating the bump member's bonding position to a uniform height. This ensures that all bump members bonded to the raised portion experience uniform pressure distribution during the bonding process, eliminating the unevenness caused by varying substrate thickness at different external terminal locations.
3Volume of moving object
If pads and external terminals overlap in plan view to reduce size, then the oscillator size is reduced, but the IC performance deteriorates due to excessive pressure on pads
Solution Approach 1:
The patent uses height dimension separation to resolve the planar overlap conflict. The bump member's top surface (bonding to IC pad) is positioned at a second height that does not overlap the external terminal in the height direction, even though their projections overlap in the plan view. This allows compact size while preventing excessive pressure on IC pads, maintaining IC reliability.
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 reduces the likelihood of excessive pressure on IC pads, thereby improving the IC's performance and reducing the risk of damage during the bonding process.
Implementation Method 1
each of the bump members is bonded to the package at a position where at least a part of the bump member does not overlap the plurality of external terminals in the plan view
Data Source
AI summary
An oscillator includes a package having a plurality of external terminals disposed on a mounting surface, a circuit element housed in the package, and a resonator which is housed in the package, and is electrically coupled to the circuit element, wherein the circuit element is electrically coupled to the package with a plurality of pads each of which is bonded to the package via a bump member, the circuit element overlaps at least one of the external terminals in a plan view, and each of the bump members is bonded to the package at a position where at least a part of the bump member does not overlap the plurality of external terminals in the plan view.