Optical Subassembly With Aperture-Aligned PCB Mounting
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Solution Overview
Problem
Conventional electro-optical assemblies face issues with structural weakness, thermal expansion-related cracking, delamination, increased thickness due to bond wires, and light obstruction, which affect manufacturing costs and efficiency.
Innovation Solution
The use of a printed circuit board with an optical semiconductor device and optical element attached on opposite surfaces, aligned through an aperture, eliminating the need for wire bonding and lead frames, and allowing for direct optical alignment and encapsulation to improve structural strength and reduce module thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a lead frame is used to mount the optical semiconductor device, then electrical connections can be established, but the structural strength is weak and the lead frame may be easily damaged during encapsulation
Solution Approach 1:
The patent removes the lead frame component entirely from the assembly. The optical semiconductor device is mounted directly to the printed circuit board without requiring a separate lead frame structure, thereby eliminating the structural weakness and durability issues associated with lead frames while maintaining electrical connection functionality through direct PCB mounting.
2Ease of operation
If wire bonding is used to connect the optical semiconductor device to the lead frame, then electrical connections are established, but the overall thickness increases and bond wire breakage may occur
Solution Approach 1:
The patent eliminates the wire bonding process by directly mounting the optical semiconductor device to the printed circuit board. This removes the bond wires that increase module thickness and are prone to breakage, while electrical connections are established through direct PCB traces and soldering, simplifying the connection process.
3Reliability
If bond wires are used for electrical connections, then conductivity is achieved, but the bond wires may partially obstruct light rays between the optics and the optical semiconductor device
Solution Approach 1:
The patent removes bond wires from the assembly by implementing direct mounting of the optical semiconductor device to the PCB. This eliminates the light obstruction problem caused by bond wires while maintaining reliable electrical connections through PCB traces and solder joints, ensuring unobstructed light paths between the optics and the semiconductor device.
4Strength
If the encapsulation compound and metal lead frame are used together, then structural support is provided, but thermal expansion mismatch causes cracks and delamination during soldering
Solution Approach 1:
The patent eliminates the metal lead frame that causes thermal expansion mismatch issues. The optical semiconductor device is mounted directly to the printed circuit board, which provides structural support while having compatible thermal expansion properties with the encapsulation compound, thereby preventing cracks and delamination during soldering and thermal cycling.
5Ease of manufacture
If conventional lead frame and wire bonding design is used, then manufacturing processes are established, but manufacturing time and costs are increased
Solution Approach 1:
The patent removes the lead frame and wire bonding steps from the manufacturing process. The optical semiconductor device is directly mounted to the printed circuit board using simplified processes such as soldering or conductive adhesive, eliminating multiple complex steps including lead frame assembly, wire bonding, and associated alignment procedures, thereby reducing manufacturing time and costs while maintaining ease of manufacture.
Data Source
AI summary
Various embodiments of optical subassemblies, and arrangements and methods for manufacturing same, for an electro-optical assembly are disclosed. One embodiment comprises an optical subassembly for an electro-optical assembly. The optical subassembly comprises a printed circuit board, an optical semiconductor device, and an optical element. The printed circuit board has a first surface, a second surface, and an aperture therethrough. The optical semiconductor device is attached to the first surface with an active region exposed to the aperture. The optical element is attached to the second surface with an optical axis exposed to the aperture and optically aligned with the active region.