Semiconductor Device Post Offset and Pad Formation
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Solution Overview
Problem
Conventional semiconductor devices face issues with electroconductive members leaking onto the mounting surface, leading to oversized solder bumps that can cause short-circuiting due to the solidification of paste within via holes during manufacturing.
Innovation Solution
A semiconductor device design featuring a substrate with a recess and electroconductive posts covered by sealing resin, where the posts are offset from the mounting surface, and pads are formed after exposing the posts to prevent leakage and ensure proper bump size, using a method that includes forming grooves, electroconductive layers, and flip-chip bonding of semiconductor elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If paste is filled into via holes for electroconductive member formation, then electrical connection is achieved, but paste leaks onto the mounting surface causing oversized solder bumps
Solution Approach 1:
The harmful leaked paste is removed from the mounting surface using a cleaning step (e.g., solvent washing or plasma treatment) before solder bump formation. This extraction of the contaminant prevents the paste from interfering with subsequent soldering processes and ensures accurate bump size control.
Solution Approach 2:
The mounting surface is cleaned and prepared in advance before the solder bump formation step. By performing preliminary cleaning to remove any potential paste leakage, the surface is ready for precise solder bump deposition, preventing oversized bumps caused by paste contamination.
2Reliability
If solder bumps are formed over leaked paste, then electrical connection is maintained, but short-circuiting occurs due to enlarged bump size
Solution Approach 1:
Leaked paste is removed from the mounting surface through cleaning processes before solder bump formation. This extraction eliminates the source of potential short-circuits and ensures that solder bumps are formed only on intended electroconductive members with proper size control.
Solution Approach 2:
The potential harmful effect of paste leakage is converted into a controlled process step. By intentionally designing the cleaning step as part of the manufacturing process, the harmful leakage is transformed into an opportunity to demonstrate process control and prevent defects, turning a potential failure mode into a quality assurance opportunity.
3Reliability
If posts are formed at the mounting surface for electrical connection, then connectivity is achieved, but leakage prevention and precise pad formation become difficult
Solution Approach 1:
Posts are formed and positioned in advance on the substrate before the sealing resin is applied and before final pad formation. This preliminary positioning allows for precise alignment and ensures that subsequent pad formation can be accurately performed without interference, simplifying the overall manufacturing process.
Solution Approach 2:
The manufacturing process is segmented into distinct steps: post formation, sealing resin application, and pad formation. By separating these steps, each can be optimized independently - posts are formed with precise positioning, sealing resin protects the structure, and pads are formed with accurate alignment, making the overall process easier to manufacture.
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 prevents leakage and ensures accurate pad formation, reducing the risk of short-circuiting and allowing for precise control over post height, enhancing the reliability and mounting efficiency of semiconductor devices.
Implementation Method 1
forming an electroconductive layer in contact with the groove and the second surface of the base member
Implementation Method 2
mounting a semiconductor element on the bottom surface of the groove so as to be electrically connected to the electroconductive layer
Data Source
AI summary
A semiconductor device includes a substrate with a recess subsiding from a selected surface of the substrate to accommodate a semiconductor element. Connected to the semiconductor element, an electroconductive portion extends from the recess onto the selected surface. A post, formed at the selected surface, has a first surface in contact with the electroconductive portion, a second surface, and a side surface between the first and second surfaces. A sealing resin covers the side surface of the post and the semiconductor element, and has a mounting surface facing in the same direction as the selected surface of the substrate. A pad, on the mounting surface of the sealing resin, is in contact with the second surface of the post. In the thickness direction, the second surface of the post is offset from the mounting surface of the sealing resin toward the selected surface of the substrate.