Split Contact Leadless Chip Carrier for Flat Mounting
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Solution Overview
Problem
The challenge in semiconductor device packaging is the difficulty in ensuring flat mounting and visible soldering quality of IC components on printed circuit boards, particularly in harsh environments, due to tilting issues during the soldering process.
Innovation Solution
The introduction of a surface-mountable non-leaded chip carrier with split contacts and a small outline diode package design, where the second contact is split into first and second portions to reduce tilting, and the use of a molding compound encapsulation that exposes side mounting surfaces for visual inspection of soldering quality, along with a lead frame arrangement and electroplating with tin for enhanced soldering characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional leadless chip carrier design is used, then manufacturing process is simplified, but tilting occurs during soldering and soldering quality becomes unobservable
Solution Approach 1:
The second contact is divided into two separate portions (first and second portions) that are arranged relative to one another. This segmentation allows the contact to better conform to the PCB surface during soldering, reducing tilting while maintaining manufacturing simplicity. The split contact structure provides multiple attachment points that distribute soldering forces more evenly.
Solution Approach 2:
The side mounting surfaces of the contacts are made visible through the molding compound encapsulation, allowing visual inspection of soldering quality. This is analogous to making the soldering state observable through surface features, enabling quality verification without complex inspection equipment like X-ray scanning.
2Productivity
If IC component is placed and soldered conventionally, then mounting is completed, but package may not lie flat and tilt occurs
Solution Approach 1:
The split second contact creates two separate mounting portions that can independently conform to the PCB surface during soldering. This segmentation prevents the entire package from tilting by distributing the mounting function across multiple contact points, ensuring the package lies flat after assembly.
Solution Approach 2:
The split contact structure is designed in advance to counteract the tilting force that occurs during soldering. By pre-configuring the contact geometry with a split, the design proactively prevents tilting before it occurs, rather than attempting to correct it after mounting.
3Productivity
If soldering quality is not visible on finished PCB, then assembly is faster, but field failure risk increases in harsh environments
Solution Approach 1:
The side mounting surfaces of the contacts are exposed through the molding compound, providing visual indication of the soldering condition. This allows operators to inspect soldering quality directly on the finished PCB without requiring X-ray scanning or other complex inspection methods, maintaining assembly speed while improving reliability verification.
Solution Approach 2:
The package structure itself provides the inspection function through its visible side mounting surfaces. The design makes the soldering quality self-evident through the exposed contact surfaces, eliminating the need for separate inspection equipment or procedures while ensuring quality verification in harsh environments.
4Reliability
If complex inspection methods like X-ray scanning are used, then soldering quality is verified, but manufacturing complexity and cost increase
Solution Approach 1:
The exposed side mounting surfaces of the contacts provide direct visual indication of soldering quality through the molding compound. This simple visual inspection method replaces complex X-ray scanning equipment, reducing manufacturing complexity and cost while maintaining reliable verification of soldering quality.
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 ensures improved manufacturability and reduces tilting during attachment to PCBs, allowing for visible inspection of soldering quality without the need for complex X-ray scanning, enhancing reliability in applications like automotive and military sectors.
Implementation Method 1
An encapsulation of molding compound envelopes the first contact and second contact
Implementation Method 2
electroplating with tin for enhanced soldering characteristics
Data Source
AI summary
Consistent with an example embodiment, there is surface-mountable non-leaded chip carrier for a semiconductor device. The device comprises a first contact. A second contact is relative to the first contact; the second contact has a split therein to provide first and second portions of the second contact arranged relative to one another to lessen tilting of a soldering condition involving attachment of the chip carrier to a printed circuit board.