Inter-Board Circuit Module Sealing With Ellipsoidal Solder Balls
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Solution Overview
Problem
Conventional circuit modules experience warpage due to heat during reflow soldering, and the use of columnar pins complicates resin sealing, leading to decreased adhesion between sealing resin and connection members.
Innovation Solution
The implementation of larger ellipsoidal solder balls that increase the contact area with the sealing resin, enhancing adhesion and preventing warpage by strengthening the connection between circuit boards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If larger solder balls are used to strengthen connection between circuit boards, then adhesion between sealing resin and connection members is improved, but resin flow obstruction increases
Solution Approach 1:
The patent applies local quality by making the solder balls ellipsoidal rather than spherical, creating different surface characteristics at different locations. The ellipsoidal shape provides increased surface area and improved adhesion properties where the resin contacts the solder ball, while the streamlined form reduces obstruction to resin flow in other directions. This localized optimization of shape resolves the contradiction between improving adhesion and reducing flow obstruction.
2Strength
If columnar pins are used to connect mounting boards, then connection strength is sufficient, but resin sealing becomes complicated and adhesion decreases
Solution Approach 1:
The patent changes the geometric parameters of the connection members from cylindrical (columnar pins) to ellipsoidal (solder balls). This parameter change transforms the shape while maintaining the connection function. The ellipsoidal shape provides better resin wettability and adhesion compared to cylindrical pins, while simplifying the sealing process. This parameter transformation resolves the contradiction between maintaining connection strength and easing the resin sealing process.
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 solution effectively suppresses warpage in circuit boards and improves the adhesion between the sealing resin and connection members, ensuring reliable electrical connections and reduced resin flow obstruction.
Implementation Method 1
one or more second solder balls located in an inter-board region between the upper circuit board and the lower circuit board and electrically connecting the upper circuit board and the lower circuit board
Implementation Method 2
a first sealing resin provided in the inter-board region so as to be in contact with the first lower main surface and the second upper main surface and cover surfaces of the one or more second solder balls
Data Source
AI summary
In a circuit module of the present disclosure, one or more solder balls have an ellipsoidal shape, are located in an inter-board region between an upper circuit board and a lower circuit board, and electrically connect the upper circuit board and the lower circuit board. The size of the second solder ball is larger than the size of the first solder ball. A first sealing resin is provided in the inter-board region so as to be in contact with a first lower main surface and a second upper main surface and to cover surfaces of the one or more second solder balls.