Printed Wiring Board Thermal Management for Simultaneous Reflow Soldering
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Solution Overview
Problem
Conventional printed wiring boards face difficulties in simultaneously reflow soldering elements with large and small heat capacities due to differences in heat conductivity, leading to potential overheating and damage of components with smaller heat capacity during the soldering process.
Innovation Solution
The printed wiring board incorporates first and second connection parts with higher heat conductivity than the board body, featuring a heat-receiving front surface, heat-receiving back surface, main-heat conducting parts, and sub-heat conducting parts, allowing for efficient heat transfer and simultaneous reflow soldering of elements with varying heat capacities using a single reflow soldering method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If both flow soldering and reflow soldering methods are used to solder elements with different heat capacities, then all elements can be soldered, but the soldering process becomes complex and time-consuming
Solution Approach 1:
The land pattern is divided into different regions with different heat conductivity characteristics. The first land has higher heat conductivity to rapidly transfer heat to elements with large heat capacity, while the second land has lower heat conductivity suitable for elements with small heat capacity. This local differentiation allows both types of elements to be soldered simultaneously through a single reflow soldering process.
Solution Approach 2:
The connection structure is segmented into multiple functional parts: the land pattern with different heat conductivity regions, the through-hole for mechanical and thermal connection, and the solder joint. This segmentation allows each part to be optimized for its specific function while working together to solve the overall soldering problem.
2Reliability
If reflow soldering is used for elements with large heat capacity, then these elements can be soldered, but elements with small heat capacity may overheat and be damaged
Solution Approach 1:
Different regions of the land pattern are assigned different heat conductivity properties. The first land region uses material or structure with higher heat conductivity to ensure adequate heat transfer to elements with large heat capacity, while the second land region uses material or structure with lower heat conductivity to protect elements with small heat capacity from overheating during reflow soldering.
Solution Approach 2:
The heat conductivity parameter of the land pattern is varied spatially to match the different thermal requirements of elements with different heat capacities. This parameter change allows the same reflow soldering process to accommodate both types of elements by adjusting the thermal characteristics at different locations.
3Reliability
If flow soldering is used for elements with small heat capacity, then these elements can be soldered, but this requires a separate soldering process from elements with large heat capacity
Solution Approach 1:
The invention merges the soldering of elements with different heat capacities into a single reflow soldering process by designing a unified land pattern structure with differentiated heat conductivity regions. This eliminates the need for separate flow soldering and reflow soldering processes, reducing total soldering time and process complexity.
4Productivity
If a single reflow soldering process is used for both types of elements, then soldering time is reduced, but heat distribution becomes difficult to control
Solution Approach 1:
The land pattern is designed with spatially varying heat conductivity properties to achieve precise heat distribution control during single reflow soldering. Each region's thermal characteristics are optimized for the specific element type it supports, enabling accurate heat management across the entire board.
Solution Approach 2:
The land pattern may use composite material structures with different thermal conductivities in different regions, allowing precise control of heat flow paths and distribution during reflow soldering. This composite approach enables simultaneous protection of heat-sensitive elements and adequate heating of heat-resistant elements.
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 design enables the simultaneous reflow soldering of elements with large and small heat capacities without overheating, preventing damage and simplifying the soldering process by optimizing heat distribution and transfer through symmetric and structured connection parts.
Implementation Method 1
The first connection part has a higher heat conductivity than a heat conductivity of the wiring board body... The main-heat conducting part is a through-hole into which a terminal of the first element is inserted, and which inter-connects the heat-receiving front surface and the heat-receiving back surface
Implementation Method 2
a reflow soldering method is used for soldering an element having a relatively small heat capacity... It is possible to connect an element having a large heat capacity and an element having a small heat capacity to the printed wiring board with a single reflow soldering
Data Source
AI summary
A printed wiring board according to an embodiment includes a wiring board body, a first connection part and a second connection part. In the first connection part, a heat-receiving front surface is a first land formed on a front surface of the wiring board body. A heat-receiving back surface is formed on a back surface of the wiring board body. A main-heat conducting part is a through-hole that inter-connects the heat-receiving front surface and the heat-receiving back surface. In the second connection part, a second land is formed on the front surface of the wiring board body. The second land is not connected to any conductor pattern formed on the back surface of the wiring board body.