Electronic Component Mounting Method Using Two-Step Heating
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Solution Overview
Problem
The existing electronic component mounting methods using solder and thermosetting resin face challenges such as long takt time, difficulty in controlling pressure, and variability in solder joint reliability due to temperature profile requirements and the need for precise alignment and wedging of solder bumps, especially when mounting multiple components simultaneously.
Innovation Solution
A method involving a two-step heating process where the thermosetting resin is first cured at a temperature lower than the solder's melting point while pressing the component, followed by releasing pressure and melting the solder at a higher temperature to form reliable solder joints, with a mounting line configuration that includes a conveyor, feeding machine, placement machine, first heating machine, and second heating machine to streamline the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bonding tool temperature is maintained at or above the solder melting point during pressing, then the solder can be melted and bonded, but the molten solder may protrude from between the component and circuit member and spread outwards, making pressure control difficult
Solution Approach 1:
The heating process is divided into two distinct stages: first heating to melt the solder while pressing, then second heating to cure the thermosetting resin after releasing the pressuring force. This segmentation allows the solder melting and bonding to occur under controlled pressure, preventing solder protrusion while ensuring reliable joint formation.
Solution Approach 2:
The solder is melted and the component is pressed together in advance during the first heating stage, establishing the bonding before the thermosetting resin cures in the second stage. This preliminary action ensures proper contact and alignment before final curing.
2Reliability
If the bonding tool is cooled down from solder melting point to resin curing temperature after each mounting, then the thermosetting resin can be cured properly, but the takt time for mounting becomes long, causing low productivity
Solution Approach 1:
The heating process is divided into two distinct stages: first heating to melt the solder while pressing, then second heating to cure the thermosetting resin after releasing the pressuring force. This segmentation allows the solder melting and bonding to occur under controlled pressure, preventing solder protrusion while ensuring reliable joint formation.
Solution Approach 2:
The bonding tool maintains a high temperature throughout both the first heating (solder melting) and second heating (resin curing) stages without cooling down in between. This continuous heating eliminates the cooling time from the takt time, significantly improving productivity while still achieving proper resin curing through the sequential heating stages.
3Productivity
If multiple electronic components are mounted simultaneously with uniform pressure, then productivity increases, but the magnitude of pressure applied varies among components, causing solder to spread at some parts and poor connection at others
Solution Approach 1:
The heating process is divided into two distinct stages: first heating to melt the solder while pressing, then second heating to cure the thermosetting resin after releasing the pressuring force. This segmentation allows the solder melting and bonding to occur under controlled pressure, preventing solder protrusion while ensuring reliable joint formation.
Solution Approach 2:
The temperature is changed in two distinct stages: first heating to a temperature that melts the solder, then second heating to a temperature that cures the thermosetting resin. This parameter change approach allows different heating requirements for solder and resin to be satisfied sequentially, ensuring both solder joint reliability and resin curing quality even when mounting multiple components simultaneously.
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 significantly shortens the takt time for mounting, ensures high reliability of solder joints, and reduces costs by allowing simultaneous mounting of multiple components with consistent pressure application and efficient use of equipment.
Implementation Method 1
heating the solder and the bonding material to cause the solder to melt and the thermosetting resin to cure
Implementation Method 2
heating the solder and the bonding material to cause the solder to melt
Implementation Method 3
The molten solder spreads between the electrodes and wets them
Data Source
AI summary
Provided is an electronic component mounting method including the steps of: placing an electronic component having a primary surface on which a first electrode is formed, on a circuit member having a primary surface on which a second electrode corresponding to the first electrode is formed, with solder and a bonding material including a thermosetting resin interposed between the first and second electrodes; subjecting the thermosetting resin to a first heating at a temperature lower than the melting point of the solder and thus causing the resin to cure, while pressing the electronic component against the circuit member, and then releasing pressure applied for the pressing; and subjecting the solder interposed between the first and second electrodes to a second heating with the pressure released, and thus melting the solder to electrically connect the first and second electrodes.