Semiconductor Clip Bonding Structure for Stable Sense Ratio
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The use of silver paste as an adhesive in semiconductor devices leads to issues such as cracks and changes in the 'sense ratio' due to its lower viscosity, making it difficult to accurately estimate current values in brushless DC motor control systems.
Innovation Solution
A semiconductor device design that includes a passivation film with a wall portion surrounding the pad, ensuring the silver paste is contained within this area, preventing protrusion and maintaining a consistent 'sense ratio' despite positional deviations of the clip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver paste is used as adhesive instead of solder, then connection reliability and on-resistance are improved, but the adhesive protrudes from the pad surface due to lower viscosity
Solution Approach 1:
The patent applies preliminary action by forming the wall portion structure before applying the silver paste adhesive. The wall portion is pre-formed on the pad surface to create containment boundaries, ensuring that when the silver paste is subsequently applied, it remains confined within the designated area and prevents protrusion while maintaining connection reliability improvements
2Reliability
If silver paste is used as adhesive, then connection reliability is improved, but the sense ratio changes due to adhesive protrusion affecting current paths
Solution Approach 1:
The wall portion is formed in advance to establish precise boundaries for the silver paste application area. This preliminary structural preparation ensures that the adhesive remains confined and does not protrude into areas that would affect current paths, thereby maintaining accurate sense ratio measurements while still achieving improved connection reliability
Solution Approach 2:
The patent applies local quality by creating a localized containment structure (wall portion) specifically around the pad area where silver paste is applied. This localized approach allows the adhesive to be contained precisely where needed, preventing it from affecting other areas of the device where accurate current measurement is critical, thus resolving the sense ratio accuracy issue
3Reliability
If the entire exposed pad surface is covered with silver paste, then connection reliability is improved, but the adhesive may short-circuit between the pad and other components
Solution Approach 1:
The wall portion is pre-formed to establish containment boundaries before silver paste application. This preliminary structure defines the exact coverage area, allowing complete pad surface coverage for improved connection reliability while preventing the adhesive from extending into areas where it could cause short-circuits between the pad and other device components
Solution Approach 2:
The patent implements local quality by creating a localized containment environment with the wall portion that allows full pad coverage with silver paste while restricting the adhesive to specific boundaries. This ensures complete coverage for reliability improvement while preventing harmful short-circuit effects in surrounding areas
Data Source
AI summary
A performance of a semiconductor device is improved. The semiconductor device includes a semiconductor chip, and a clip mounted on the semiconductor chip via a silver paste. Here, the semiconductor chip includes a passivation film having an opening, a source pad of a main transistor having a portion exposed from the passivation film at the opening, and a wall portion provided on the passivation film so as to surround the source pad in a plan view. At this time, a whole of the portion (exposed surface) of the source pad, which is exposed from the passivation film, is covered with the silver paste. Further, in the plan view, the silver paste connecting the source pad with the clip is positioned inside of an area surrounded by the wall portion, without overflowing.