Photoelectric Composite Board Alignment via Reference Mark
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Solution Overview
Problem
The conventional method for forming photoelectric composite boards results in positional displacement of electrode pads during the solder resist layer formation process, leading to inaccurate alignment of the optical axis of the photoelectric transducer with the light deflector, causing significant signal leakage loss between the optical and electric circuits.
Innovation Solution
A method involving the formation of a light guide layer with a light deflector, where mounting lands are created, and solder resist layers are applied to cover these lands. A reference point is set above the light deflector, and coordinates are defined for the electrode pads to ensure precise alignment, eliminating errors associated with photo-mask positioning, allowing for accurate formation of electrode pads directly exposed on the solder resist layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If photo-mask alignment is used to form electrode pads on a printed circuit board, then the electrode pads can be formed using conventional PCB manufacturing processes, but positional displacement occurs due to resin contraction or photo-mask displacement during heating processes, resulting in inaccurate alignment of the optical axis of the photoelectric transducer with the light deflector
Solution Approach 1:
A reference mark is introduced as an intermediary element on the light guide layer to establish a stable reference frame for coordinate definition. This reference mark serves as a mediator between the light deflector position and the electrode pad formation process, eliminating the need for photo-mask alignment and preventing positional displacement during heating processes.
Solution Approach 2:
The conventional photo-mask alignment mechanism is replaced with a coordinate definition system based on a reference point. Instead of using mechanical/photochemical alignment processes that are susceptible to displacement, the invention uses a coordinate system referenced to the light deflector position, thereby substituting a fragile mechanical alignment system with a more stable coordinate-based system.
2Ease of manufacture
If photo-mask alignment is used to form electrode pads, then conventional PCB manufacturing processes can be utilized, but displacement of the photo-mask during alignment results in a disagreement of several tens of μm between optical axes, causing significant signal leakage loss
Solution Approach 1:
The reference mark on the light guide layer acts as an intermediary that directly links the light deflector position to the electrode pad coordinates. This intermediary eliminates the need for photo-mask alignment and prevents the tens of micrometers of displacement that cause signal leakage loss between the optical circuit and electric circuit.
Solution Approach 2:
The photo-mask alignment mechanical system is replaced with a coordinate definition system that references the light deflector position directly. This substitution eliminates the mechanical displacement issues inherent in photo-mask alignment and prevents the resulting optical axis misalignment that causes signal energy loss.
3Ease of manufacture
If electrode pads are formed using conventional photoresist processes with photo-mask alignment, then the manufacturing process can be standardized, but resin contraction during heating processes displaces the center of light emitting or receiving portions, making it difficult to mount the photoelectric transducer at the accurate position
Solution Approach 1:
The reference mark on the light guide layer serves as a stable intermediary reference that is not affected by resin contraction during heating processes. This reference mark provides a consistent reference point for defining electrode pad coordinates, eliminating the positioning accuracy problems caused by photo-mask displacement and resin contraction.
Solution Approach 2:
The photo-mask alignment mechanical system is replaced with a coordinate definition system based on a reference point that is independent of resin contraction effects. This substitution provides stable, accurate positioning for photoelectric transducer mounting that is not susceptible to thermal deformation of the resin materials.
Data Source
AI summary
In a method for forming a photoelectric composite board (10) on which a photoelectric transducer (5) is mounted, photo-masks (111, 112, 113) which are used in processes to form the photoelectric composite board (10) are respectively disposed on the basis of a reference mark (33) previously formed on a metal thin film (101). In addition, openings (22) are formed on solder resist layers (8) by irradiating laser beams at positions defined on the basis of a reference point (4a) defined above a light deflector (4) formed on an end of a light guide (3).