Solid-State Image Sensor Spacer for Distance Stability
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Solution Overview
Problem
The existing solid-state image pickup devices face challenges in maintaining accurate separation distance between the solid-state image pickup element and the optical element due to limitations in molding accuracy and thermal expansion of package materials, which affects the device's performance.
Innovation Solution
A solid-state image pickup device where the separation distance is determined by the thickness of a spacer with high electrical and thermal conductivity, made of aluminum nitride, which is easily machinable for precise dimensional accuracy, and includes positional alignment marks for improved assembly accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the separation distance is determined by package molding accuracy, then the device structure is simple, but the separation distance accuracy is insufficient
Solution Approach 1:
A spacer is introduced as an intermediary component between the solid-state image pickup element and the optical element. The spacer has a predetermined thickness that precisely determines the separation distance, eliminating dependence on package molding accuracy. The spacer includes a through-hole for light transmission and positioning features for accurate assembly.
2Ease of manufacture
If resin package material is used, then the device is easy to manufacture, but thermal expansion causes separation distance fluctuation
Solution Approach 1:
The spacer is made from a material with specific thermal properties (low thermal expansion coefficient) to maintain dimensional stability. By changing the material parameter selection, the spacer resists thermal expansion and contraction, keeping the separation distance stable across temperature variations while allowing standard manufacturing processes.
3Stability of the object's composition
If ceramic package material is used, then thermal expansion is reduced, but molding accuracy variation affects separation distance
Solution Approach 1:
The package structure is segmented into distinct functional components: the package body (ceramic or resin), the spacer (separation component), and the mounting structures. By separating the separation distance determination function into the spacer component, the precision requirement is isolated from the package molding process, allowing each component to be optimized independently.
4Manufacturing precision
If the spacer thickness determines separation distance, then separation distance accuracy is improved, but additional component increases assembly complexity
Solution Approach 1:
The spacer serves multiple functions simultaneously: it determines the separation distance through its thickness, provides structural support between components, guides positioning through integrated features, and allows light transmission through its through-hole. This multi-functionality reduces the need for additional separate components and simplifies the overall assembly process.
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 solution stabilizes the electrical characteristics of the solid-state image pickup element by enhancing heat radiation and maintaining a consistent separation distance, independent of package molding accuracy, while simplifying the assembly process through precise positional alignment.
Implementation Method 1
the spacer has high electrical and thermal conductivity... enhancing heat radiation
Implementation Method 2
the spacer has high electrical and thermal conductivity... made of aluminum nitride
Data Source
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AI summary
A solid-state image pickup device comprising: a multilayer wiring board 2 having an opening portion 21; a spacer 3 covered with a conductive film 32, and fixed to the multilayer wiring board 2 in a state of making the conductive film 32 face contact with a reference potential electrode exposed into the opening portion 21 of the multilayer wiring board 2; a solid-state image pickup element 4 fixed to the spacer 3 in a state of face contact with the conductive film 32 of the spacer 3, and arranged in the opening portion 21; and an optical element 5 fixed at a position opposing the solid-state image pickup element 4 via the spacer 3, and transmitting light into the opening portion.