Power Module Lead Frame Hole for UV Resin Adhesion
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Solution Overview
Problem
The existing power modules face challenges with insufficient adhesion of sealing resin to ceramic boards, particularly due to low adhesion strength, which affects reliability and productivity, especially when dealing with high voltage and large currents, and the difficulty in radiating UV light to shaded regions under the electrode plates.
Innovation Solution
The power module design incorporates an opening or bent portion in the electrode plate that overlaps with the insulative board where no conductor layer is formed, allowing UV light to reach the ceramic board, enhancing the adhesive strength of the sealing resin by improving UV radiation coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the electrode plate is made wider to handle higher voltage and current, then the power handling capability is improved, but UV light cannot reach the shaded region under the electrode plate, causing insufficient adhesion of sealing resin
Solution Approach 1:
The electrode plate is segmented by forming a through-hole in it, which divides the structure into regions that allow UV light to pass through. This segmentation enables the UV light to reach the shaded region under the electrode plate, improving sealing resin adhesion while maintaining the overall power handling capability of the wider electrode plate structure
2Reliability
If UV radiation time is increased to improve sealing resin adhesion, then adhesion is improved, but productivity decreases
Solution Approach 1:
The through-hole structure is formed in advance in the electrode plate, which preliminarily creates the condition for UV light to reach the shaded region. This preliminary structural preparation eliminates the need for extended UV radiation time, as the UV light can now effectively reach all necessary areas through the hole, thus improving adhesion without sacrificing productivity
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 significantly enhances the adhesive strength of the sealing resin to the ceramic board, improving the reliability and productivity of the power module by ensuring better UV light penetration and adhesion, even in areas previously shaded by the electrode plates.
Implementation Method 1
UV radiation is applied in some cases in order to improve such a situation
Implementation Method 2
a surface of an area of the insulative board other than an area thereof where the conductor layer is formed, is excited by radiation of UV light
Data Source
AI summary
An object is to provide a power module in which adhesion of a sealing resin is sufficient and which is highly reliable. The power module includes: an insulative board in which a pattern of a conductor layer is formed on a ceramic plate; power semiconductor elements placed on the insulative board; lead frames each in a plate shape connecting from electrodes of the power semiconductor elements to screw-fastening terminal portions; and a sealing resin portion that seals connection portions between the power semiconductor elements and the lead frames, and regions around the connection portions; wherein, in the lead frames, opening portions are formed at positions where each of the lead frames at least partly overlaps, in planar view, with a portion of the insulative board on which the conductor layer is not formed.