Thermosetting Resin Mounting Method for Void Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electronic component mounting methods using thermosetting resin for sealing gaps between components and boards face issues such as reduced bonding reliability due to thermal stress, void formation from air bubbles, and filler interposition, especially with downsized components and lead-free soldering.
Innovation Solution
A method involving a thermocompression bonding process where a liquid thermosetting resin is applied in a glob shape outside the electronic component mounting region, allowing it to enter the gap by capillarity during bonding, ensuring complete filling and curing before cooling, thus preventing voids and reinforcing bonded areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resin sealing is performed by postcoating (injecting resin after metal bonding), then the bonding process can be completed first, but the reinforcing effect of resin sealing cannot be obtained during the metal bonding process, leading to thermal stress-induced cracks and breakage
Solution Approach 1:
The resin is applied to the board before the electronic component is mounted, so that the resin is already in position to provide reinforcement during the metal bonding process. This preliminary action ensures that the resin sealing and metal bonding processes occur simultaneously, allowing the resin to prevent thermal stress-induced cracks and breakage during bonding.
2Reliability
If resin sealing is performed by precoating (applying resin before mounting), then the resin can be in position during bonding, but air bubbles enter the gap and remain as voids, impairing the strength of the sealing resin
Solution Approach 1:
The resin is applied in a state that allows it to flow and fill the gap dynamically during the bonding process. The resin's流动性 (fluidity) is maintained during bonding, allowing it to escape air bubbles and fill voids as the electronic component is pressed against the board, thereby eliminating the harmful voids while maintaining reinforcement.
3Reliability
If a resin including filler is used for precoating, then the physical properties can be adjusted, but filler interposition occurs between electrodes and bumps, impairing bonding reliability
Solution Approach 1:
The resin with filler is applied in a specific pattern or distribution that ensures filler particles are positioned away from the electrode and bump areas. This local quality control prevents filler interposition at critical bonding interfaces while still providing the desired physical property adjustments in the sealing resin.
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 enhances bonding reliability by preventing voids and thermal stress-induced breakage, ensuring robust connections even with downsized components and lead-free soldering, while allowing the use of fillers without interposition issues.
Implementation Method 1
a liquid thermosetting resin is applied in a glob shape outside the electronic component mounting region, allowing it to enter the gap by capillarity during bonding
Implementation Method 2
heating the thermosetting resin so that entry of the thermosetting resin in the liquid glob state into a gap between the board and the electronic component in the electronic component mounting region is promoted and thermosetting reaction of the thermosetting resin which has entered the gap is promoted
Data Source
AI summary
By an electronic component mounting method for electrically connecting bumps to board electrodes, in a contact process for placing a thermosetting resin in a liquid glob state on the board surface and bringing the lower surface of the electronic component into contact with the thermosetting resin, the bumps are pressurized against the electrodes in positional alignment in a liquid glob distribution state where one portion of the liquid glob is arranged inside an electronic component mounting region and a remaining portion greater in liquid measure than the one portion is arranged outside the electronic component mounting region. The thermosetting resin enters into a gap between the electronic component and the board by capillarity in a thermocompression bonding process. This prevents voids occurring in the sealing resin, reinforces bonded portions of bumps and electrodes with thermally cured thermosetting resin, thereby preventing bonded portion breakage due to thermal stress generated during cooling.