Radiant-Heat PCB Soldering for Dense Circuit Interconnects
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Solution Overview
Problem
Existing methods for joining printed circuits, such as mechanical connectors and anisotropic conductive film bonding, face challenges like volumetric constraints, weight, cost, and reliability issues, particularly in lightweight and compact electronic devices, and are not suitable for forming dense, reliable connections with high conductivity and mechanical strength.
Innovation Solution
The use of non-contact radiant heat from an external source to form solder joints between printed circuits, allowing for a two-dimensional pattern of solder joints with smaller pitch and higher density, which is mechanically stronger and more reliable compared to traditional methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical connectors are used to join printed circuits, then electrical connection is achieved, but volumetric constraints and weight increase
Solution Approach 1:
The patent replaces mechanical connectors with a soldering process that uses radiant heat (infrared energy) to join printed circuits. This substitution eliminates the need for bulky mechanical connector structures while achieving reliable electrical connections through solder joints, thereby reducing device volume and weight while maintaining connection reliability
Solution Approach 2:
The patent changes the heating method from contact-based thermal conduction to radiant heat transfer using infrared energy. This parameter change in the heating mechanism enables non-contact soldering, allowing for more compact device design without compromising the soldering process effectiveness or connection reliability
2Reliability
If anisotropic conductive film bonding is used to join printed circuits, then electrical connection is achieved, but weight and cost increase
Solution Approach 1:
The patent replaces anisotropic conductive film bonding with traditional soldering using radiant heat. This substitution eliminates the need for additional conductive film materials, reducing device weight and cost while achieving more reliable solder joints that provide both electrical connection and mechanical strength
Solution Approach 2:
The patent uses solder material as a composite joining medium that provides both electrical conductivity and mechanical bonding strength. This composite approach replaces the need for separate conductive films and mechanical connectors, reducing overall weight while maintaining connection reliability
3Manufacturing precision
If traditional contact-based heating is used for soldering, then solder reflow is achieved, but heat distribution uniformity deteriorates
Solution Approach 1:
The patent replaces contact-based thermal conduction with radiant heat transfer using infrared energy. This substitution enables uniform heat distribution across the solder joints without the localized heating and pressure variations associated with contact-based methods, improving manufacturing precision and heat distribution uniformity simultaneously
Solution Approach 2:
The patent employs controlled radiant heating with specific timing and intensity patterns to achieve uniform solder reflow. By regulating the radiant heat application in a controlled manner, the process achieves consistent heat distribution across all solder joints, improving both manufacturing precision and thermal uniformity
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 approach reduces size and weight, enhances conductivity, and improves reliability by forming strong, lightweight connections that are more robust than mechanical connectors and anisotropic conductive film bonds, while allowing for smaller form-factor electronic devices with increased connection density.
Implementation Method 1
applying radiant heat via an infrared light source to the second surface of the second printed circuit
Implementation Method 2
the radiant heat incident on the via causes the via to conduct heat to solder located at an interface of the contact and the via
Data Source
AI summary
Examples are disclosed related to forming solder joints between printed circuits by using radiant heat. One example provides a method of manufacturing an electronic device, the method comprising aligning a contact of a first printed circuit with a via of a second printed circuit. The method further comprises applying radiant heat via an infrared light source to a second surface of the second printed circuit, the radiant heat incident on the via to cause the via to conduct heat to solder located at an interface of the contact and the via, and after heating the solder to reflow, cooling the solder, thereby forming a solder joint between the contact of the first printed circuit and the via of the second printed circuit.