Image Sensor Flatness via Segmented Substrate and Fixed Area Routing
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Solution Overview
Problem
Conventional image pickup modules suffer from reduced flatness of the light receiving surface due to differences in contraction between soldered and unsoldered areas, leading to degraded image quality, as the semiconductor substrate's low rigidity complicates the formation of through-hole electrodes and affects the manufacturing process.
Innovation Solution
An image pickup module design featuring a cover member, an image pickup device chip with through-hole electrodes, a fixing member to connect the cover member and chip, a rewiring substrate, and a connection member, where the through-hole electrodes and connection members are strategically arranged in a fixed area to enhance rigidity and facilitate stable connections, using materials with similar thermal expansion coefficients to minimize stress and maintain high flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the thickness of the semiconductor substrate is increased to improve rigidity and flatness, then the flatness of the light receiving surface is improved, but the through-hole electrodes become difficult to be formed
Solution Approach 1:
The semiconductor substrate is divided into two distinct regions: a first region with a first thickness and a second region with a second thickness greater than the first thickness. This segmentation allows the light receiving surface to maintain high flatness through the thicker first region while the thinner second region facilitates easier formation of through-hole electrodes.
Solution Approach 2:
Different regions of the semiconductor substrate are given different thicknesses to optimize local functions. The first region has a first thickness optimized for light reception and flatness, while the second region has a greater second thickness optimized for through-hole electrode formation and structural support.
2Productivity
If the thickness of the semiconductor substrate is decreased to improve throughput and reliability of through-hole electrode formation, then the ease of manufacture is improved, but the rigidity of the semiconductor substrate becomes low causing concaves and convexes
Solution Approach 1:
The substrate is segmented into regions of different thicknesses, allowing the overall substrate to maintain sufficient rigidity through the thicker second region while enabling easier through-hole electrode formation in the thinner first region, thus improving manufacturing throughput.
Solution Approach 2:
The semiconductor substrate employs local quality variation with different thicknesses in different regions. The first region has a thinner profile for ease of through-hole electrode formation, while the second region provides the necessary rigidity and structural support.
3Reliability
If solder balls are arranged below a hollow portion to connect the image pickup device with the mounting substrate, then the connection is achieved, but concaves and convexes are formed in the image pickup device chip according to positions of solders
Solution Approach 1:
The semiconductor substrate is pre-formed with a non-uniform thickness profile before the soldering process. The first region is made thinner and the second region is made thicker in advance, so that when solder balls are attached and the substrate is cooled, the pre-existing thickness variation compensates for the contraction differences, preventing concave formation and maintaining light receiving surface flatness.
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
The solution achieves a high-quality image by maintaining the flatness of the light receiving surface and improving the reliability and yield of the connection process, reducing stress on the semiconductor substrate and ensuring a stable electrical and mechanical connection.
Implementation Method 1
a fixing member arranged around the image pickup device chip and configured to connect the cover member and the image pickup device chip together
Implementation Method 2
a connection member configured to connect the image pickup device chip with the rewiring substrate
Implementation Method 3
there is a difference of contraction between a portion where the solder attaches and a portion where no solder attaches
Data Source
AI summary
An image pickup module includes a cover member, an image pickup device chip including photodiodes, a fixing member which is arranged around the image pickup device chip and which connects the cover member and the image pickup device chip together, a rewiring substrate arranged on the side opposite to the cover member of the image pickup device chip, connection members for connecting the image pickup device chip with the rewiring substrate, and a space surrounded by the cover member, the image pickup device chip, and the fixing member. The image pickup device chip includes a semiconductor substrate. The semiconductor substrate includes through-hole electrodes penetrating the substrate. When an area corresponding to the fixing member in the orthogonal projection of the image pickup module with respect to the cover module is defined as a fixed area, the through-hole electrodes and the connection members are arranged in the fixed area.