Semiconductor Proximity Sensor with Segmented Bonding Wires
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Solution Overview
Problem
Semiconductor devices with proximity sensors face challenges in reducing the center distance between light-receiving and light-emitting elements while minimizing noise and optical interference, leading to detection errors and performance issues due to close proximity of bonding wires and potential lens surface scratches during manufacturing.
Innovation Solution
A semiconductor device configuration with internal terminals and bonding wires arranged to reduce noise and optical interference, featuring a light-transmitting member covering the elements and a light-shielding member with a partition wall to isolate light paths, and a manufacturing method using a secondary mold to minimize lens surface contact and reduce the size of the light-shielding resin opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the light-receiving element and light-emitting element are mounted close to each other to reduce the center distance, then the optical window size is reduced, but noise from the light-emitting element's electric current interferes with the light-receiving element's detection
Solution Approach 1:
The bonding wires are segmented into two separate groups: first bonding wires connecting light-receiving element electrodes to first internal terminals, and second bonding wires connecting light-emitting element electrodes to second internal terminals. This spatial segmentation of electrical connections prevents noise interference while maintaining compact element placement.
Solution Approach 2:
Internal terminals serve as intermediary connection points between the light-receiving element, light-emitting element, and external terminals. The first internal terminals and second internal terminals are electrically isolated from each other, acting as mediators that enable separate signal paths and prevent noise coupling between the sensitive light-receiving element and the high-current light-emitting element.
2Area of stationary object
If a metal mold is pressed against the entire lens surface to form the light-shielding resin part, then the opening size is minimized, but the lens surface may be scratched reducing light transmission
Solution Approach 1:
The light-transmitting resin part is extracted as a separate component with a pre-formed lens, rather than being molded together with the light-shielding resin part. This separation allows the lens surface to be formed without direct contact from the metal mold during light-shielding resin injection, preventing scratches while maintaining a compact overall structure.
Solution Approach 2:
The lens is pre-formed in the light-transmitting resin part before the light-shielding resin part is injected. This preliminary formation of the lens surface protects it from damage during subsequent molding operations, as the lens surface does not require direct mold contact for its formation.
3Length of stationary object
If the center distance between light-receiving element and light-emitting element is reduced, then more light is reflected from the boundary plane and reaches the light-receiving element, causing detection errors
Solution Approach 1:
The light-shielding resin part, which blocks stray light, is strategically positioned to cover the boundary plane between the optical window and outside. This converts the potentially harmful reflected light from the boundary plane into a beneficial shielding effect, preventing erroneous detection while allowing compact element placement.
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 configuration achieves a shorter center distance between light-receiving and light-emitting elements, reduces noise, and enhances detection accuracy by minimizing optical interference and lens surface damage during manufacturing.
Implementation Method 1
A semiconductor device serving as a proximity sensor emits infrared radiation from its light-emitting element such as a light-emitting diode (LED)
Implementation Method 2
detects the infrared radiation that is reflected from a target object with its light-receiving element such as a photo-diode
Implementation Method 3
Each electrode is electrically connected to the light-receiving element or to the light-emitting element via a bonding wire
Data Source
AI summary
A semiconductor device includes a substrate having a mounting surface, a plurality of internal terminals disposed on the mounting surface, a light-receiving element mounted on the mounting surface, a light-emitting element mounted on the mounting surface, a first bonding wire and a light-transmitting element. The light-receiving element has a light-receiving region that detects light and a plurality of element pad portions. At least one of the plurality of element pad portions is electrically connected to the light-receiving region. The light-emitting element is spaced apart from the light-receiving element along a first direction perpendicular to a thickness direction of the substrate. The first bonding wire connects one of the plurality of element pad portions of the light-receiving element to one of the plurality of internal terminals. The first bonding wire is located on a side of the light-receiving element opposite the light-emitting element along the first direction.