Sequential Soldering of Electronic Modules via Global and Local Heating
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Solution Overview
Problem
Current electronic module manufacturing processes face challenges with temperature gradients causing thermal stresses, heat exchange limitations, obscured component visibility, and height restrictions due to bulkier components, leading to performance degradation and premature aging.
Innovation Solution
A method involving global heating for initial solder fusion, followed by local heating using electrodes for precise soldering of components, allowing for sequential placement and reduced thermal impact on components, with a production line incorporating units for global and local heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If global heating through reflow oven is used to melt solder, then solder fusion is achieved, but temperature gradients cause thermal stresses on components
Solution Approach 1:
The patent divides the soldering process into two separate stages: first, a reflow oven performs global heating to melt solder for small components; second, a selective wave soldering stage applies localized heating only to specific areas where larger components need soldering. This segmentation eliminates temperature gradients across the entire board, as each stage targets only the necessary components, thereby reducing thermal stress on temperature-sensitive components.
Solution Approach 2:
The patent performs preliminary soldering of small components using the reflow oven before placing and soldering larger components. By completing the global heating and solder fusion first, then adding larger components in a second stage with controlled localized heating, the process prevents thermal stress on components that would be damaged by subsequent high-temperature exposure.
2Adaptability or versatility
If bulkier components are placed on the board, then component functionality is improved, but heat exchange is limited and components obscure other parts
Solution Approach 1:
The patent segments the soldering process into two distinct stages, allowing different component types to be handled appropriately. Small components are soldered in the first global heating stage, while larger components are added and soldered in the second localized stage. This enables the board to accommodate both small and large components without the large components interfering with the heating process or obscuring inspection of smaller components, as the smaller components are already in place and visible before larger ones are added.
3Reliability
If reflow oven passage is used for soldering, then solder fusion is achieved, but maximum component height is limited
Solution Approach 1:
The patent separates the soldering process into two stages: initial reflow oven heating for low-profile components, followed by selective wave soldering for taller components. The wave soldering process uses a wave of molten solder that flows over the board surface, allowing it to reach and fuse with taller component leads without requiring the entire board to pass through a reflow oven at high temperature, thus accommodating greater component heights.
4Reliability
If solder melting temperature is increased to meet new standards, then solder composition compliance is improved, but thermal stresses on components increase
Solution Approach 1:
The patent applies local quality by using selective wave soldering that delivers high-temperature molten solder only to specific localized areas where components need soldering, rather than heating the entire board uniformly. This allows the use of higher-melting-point solder materials that meet new composition standards while limiting thermal exposure to only the solder joints, protecting temperature-sensitive components from excessive thermal stress.
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 enables uniform solder fusion, rapid and precise soldering, reduces thermal stresses, and allows for the use of components with average temperature resistance, while enabling visual inspection and accommodating bulkier components without heat damage.
Implementation Method 1
a global heating unit for melting a solder placed between the components of the first type and the circuit
Implementation Method 2
a local heating unit for melting a solder disposed between the components of the second type and the circuit, characterized in that the welding of the component of the second type is carried out by applying two electrodes to each leg of the component and by causing an electric current to flow between the electrodes to heat each leg of the component
Data Source
Figure 1~3
AI summary
The invention relates to a method for producing an electronic module (2) comprising a printed circuit (4) board (3), at least one first type of component (5), and a second type of component (6), said method comprising the following steps: solder (8) is placed on the board; the first type of component is placed in position; the board is generally heated in order to melt the solder in such a way as to solder the first type of component; the second type of component is positioned in such a way that it has tongues (7) which are supported on the board by means of solder; and the solder is locally heated such that it melts in order to solder the second type of component. The invention also relates to a production line for implementing said method.