Vehicular Camera Assembly with Mixed CTE Housing
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Solution Overview
Problem
Vehicle cameras face challenges due to extreme temperature changes, leading to warping of printed circuit boards (PCBs) and subsequent focus shifts, as existing materials with low coefficient of thermal expansion (CTE) cannot adequately compensate for the expansion and contraction of camera components.
Innovation Solution
The camera design incorporates a combination of low CTE materials for the housing and high CTE materials for lens attachment, using overmolded plastic to bond with the lens barrel, which compensates for movement along the Z-axis while maintaining alignment with low CTE materials limiting movement in the X and Y axes, thus preventing PCB warping and focus shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If low CTE materials are used for the entire camera housing, then PCB warping is reduced, but focus shifts occur due to insufficient compensation for component expansion and contraction
Solution Approach 1:
The camera housing is divided into regions with different CTE properties: the main housing structure uses low CTE material for stability, while specific lens mounting portions use high CTE material for compensation. This local differentiation allows simultaneous achievement of PCB stability and focus precision.
Solution Approach 2:
The housing combines low CTE material (for structural stability) with high CTE material portions (for thermal compensation). This composite approach allows the housing to simultaneously provide structural integrity and thermal expansion compensation to prevent both PCB warping and focus shifts.
2Manufacturing precision
If high CTE materials are used for lens attachment, then focus shifts are compensated, but PCB warping increases due to excessive expansion
Solution Approach 1:
High CTE material is applied only to specific lens mounting portions rather than the entire housing. This localized application provides focus compensation where needed while limiting overall expansion that would cause PCB warping.
Solution Approach 2:
The high CTE material portions are strategically designed to expand in specific directions and magnitudes that compensate for lens focus shifts, while the low CTE main housing limits overall thermal expansion to prevent PCB warping.
3Ease of manufacture
If a single material is used for the housing, then manufacturing is simplified, but neither PCB warping nor focus shifts can be adequately addressed
Solution Approach 1:
The housing uses a composite structure combining low CTE and high CTE materials in specific configurations. While manufacturing complexity increases slightly, this approach reliably addresses both PCB warping and focus shifts, ensuring stable camera operation in varying temperatures.
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 effectively prevents PCB warping and maintains camera focus and alignment across varying temperatures, ensuring reliable operation in extreme conditions.
Implementation Method 1
a first portion (230) comprising a first material with a first coefficient of thermal expansion (CTE) and a second portion (230) comprising a second material with a second CTE, wherein the first CTE is higher than the second CTE
Data Source
AI summary
A vehicular camera assembly includes a first portion, a second portion and a lens barrel accommodating a lens. The lens barrel has a first end and a second end. The first portion of the vehicular camera assembly is formed of plastic and the second portion is formed of metal. The first portion of the vehicular camera assembly receives the first end of the lens barrel, and the lens barrel is bonded at the first portion of the vehicular camera assembly via adhesive. The first portion of the vehicular camera assembly has a first coefficient of thermal expansion (CTE), and the second portion of the vehicular camera assembly has a second CTE. The first CTE is higher than the second CTE. The adhesive has a third CTE that is higher than the second CTE.