LCP Solder Mask for Fine-Pitch Interconnections
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Solution Overview
Problem
The miniaturization of integrated circuits with closely spaced pins creates a technology gap in interconnection with printed circuit boards, as solder pads on these boards are not miniaturizing at the same rate, leading to larger package sizes and the need for flexible, non-brittle substrates to accommodate these devices.
Innovation Solution
A method involving a liquid crystal polymer (LCP) substrate and solder mask, where the LCP solder mask is formed with apertures aligned with solder pads, allowing for precise lamination and the use of solder paste to attach integrated circuits, with the process involving punching, laser milling, and autoclave lamination for precise alignment and attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional solder masks are used on printed circuit boards, then the solder pads can be attached, but the package size becomes larger due to the technology gap between integrated circuit miniaturization and solder pad miniaturization
Solution Approach 1:
The patent changes the material parameter of the solder mask from conventional materials to liquid crystal polymer (LCP), which has unique properties including the ability to maintain dimensional stability at high temperatures and support finer pitch solder pads. This material parameter change enables both reduced package size and improved manufacturing precision for closely spaced pins
Solution Approach 2:
The patent uses a composite structure where the solder mask is made of LCP material combined with copper foil and adhesive layers. This composite material approach allows the solder mask to simultaneously provide electrical isolation, mechanical strength, and thermal stability required for fine-pitch interconnections
2Strength
If rigid substrates are used for printed circuit boards, then structural strength is maintained, but the device cannot accommodate flexible design requirements and miniaturization
Solution Approach 1:
The patent changes the substrate material parameter from rigid conventional materials to LCP, which has inherent flexibility while maintaining structural integrity. The LCP substrate can bend and flex without breaking, enabling flexible circuit board designs while still providing the strength needed for mechanical support
3Ease of operation
If extra routing layers are added to handle closely spaced pins, then interconnection is achieved, but the package size increases
Solution Approach 1:
The patent changes the solder mask material to LCP, which enables the creation of finer pitch solder pads and more compact routing. This material parameter change allows interconnection of closely spaced pins without requiring additional routing layers, thus maintaining ease of operation while reducing package size
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
This method enables the creation of thinner, more flexible electronic devices with finer pitch solder pads, improved positional accuracy, and superior electrical isolation, allowing for effective attachment of electronic components with reduced device size and enhanced mechanical strength.
Implementation Method 1
The LCP solder mask and LCP substrate are aligned, and then laminated together
Implementation Method 2
The LCP solder mask and LCP substrate are aligned, and then laminated together via the application of heat and pressure
Implementation Method 3
punching, laser milling
Data Source
Figure 1
Figure 2A~2E
Figure 2F
AI summary
A method of making an electronic device includes forming a circuit layer on a liquid crystal polymer (LCP) substrate and having at least one solder pad. The method also includes forming an LCP solder mask having at least one aperture therein alignable with the at least one solder pad. The method further includes aligning and laminating the LCP solder mask and the LCP substrate together, then positioning solder paste in the at least one aperture. At least one circuit component may then be attached to the at least one solder pad using the solder paste.