Optical Semiconductor Device With Package Overhang
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Solution Overview
Problem
Conventional resin-sealed optical semiconductor devices face issues with sealing resin overflow and bleeding due to reduced sidewall height, which hinders electrical conduction and optical performance, and makes it difficult to use the transparent member's top surface as an optical reference surface.
Innovation Solution
The optical semiconductor device features a package with an overhang portion that projects inward, allowing the sealing resin to fill the space between the package and the semiconductor chip while exposing the transparent member's top surface and shielding its side end faces, preventing resin overflow and enabling the use of the transparent member's top surface as an optical reference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the height of the sidewall portion of the package is lowered to reduce product thickness, then the thickness is reduced, but sealing resin overflows over the sidewall portion or causes bleeding
Solution Approach 1:
The package structure introduces an overhang portion that extends horizontally inward from the sidewall, creating a multi-level top surface. This dimensional change allows the package top surface to be positioned lower than before while the overhang portion provides physical restraint against resin overflow, effectively decoupling the thickness reduction from resin overflow problems.
2Measurement precision
If the top surface of the package is located lower than the top surface of the transparent member to use it as an optical reference surface, then optical reference accuracy is improved, but the height of the sidewall portion cannot be increased and resin overflow is likely to occur
Solution Approach 1:
The overhang portion creates a stepped configuration where the main package top surface remains low for optical reference accuracy, while the overhang extends horizontally to provide mechanical containment for the sealing resin, preventing overflow despite the lowered package surface.
3Reliability
If the side end faces of the transparent member are covered with sealing resin to prevent entry of unwanted incident light, then optical performance is improved, but it is difficult to cover them due to resin overflow when sidewall height is reduced
Solution Approach 1:
The overhang portion creates a horizontal barrier that enables the sealing resin to be applied and contained at the desired location, allowing complete coverage of the transparent member's side end faces for optical shielding without the resin overflowing onto the package exterior.
Data Source
AI summary
An optical semiconductor device includes: a package having a bottom portion and a sidewall portion; a semiconductor chip having an optical element formed on one surface thereof and having an opposite surface to the one surface fixed to the bottom portion of the package; a transparent member fixed to the semiconductor chip so as to cover the optical element; and a sealing resin filling a space between the package and the semiconductor chip. The sidewall portion has in an upper part thereof an overhang portion that projects toward inside of the package. The transparent member is exposed from a window portion formed by the overhang portion.