Insulated Testing Lands on Semiconductor Lead Frames
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Solution Overview
Problem
Testing multiple wire connections in semiconductor devices is challenging due to multiple wires being at the same voltage, particularly in power devices with conventional lead frames.
Innovation Solution
The implementation of plural testing lands on leads in a lead frame, which are insulated from each other and the bulk of the lead, allowing for different electrical paths outside the molded package body, using a stacked arrangement of conductive materials and insulating layers, and the deposition of conductive and insulating layers on lead tips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple wires are connected on a same lead using conventional lead frames, then the device structure is simple, but wire connection testing becomes difficult due to multiple wires being at the same voltage
Solution Approach 1:
The lead frame structure is segmented by providing multiple testing lands (first testing land, second testing land) on the same lead, which are electrically insulated from each other. This segmentation allows individual testing of multiple wire connections that are connected to the same lead, resolving the testing difficulty while maintaining structural simplicity.
Solution Approach 2:
Testing lands are introduced as intermediary elements between the wire connections and the external testing equipment. These testing lands provide isolated electrical contact points that enable individual voltage measurement of each wire connection, acting as mediators that solve the voltage conflict problem.
2Difficulty of detecting and measuring
If plural testing lands are provided on leads with insulation, then wire connection testing becomes effective, but the manufacturing process becomes more complex
Solution Approach 1:
The testing lands are arranged in a stacked configuration along the lead, utilizing the vertical dimension rather than spreading them out horizontally. This dimensional change allows multiple insulated testing lands to be accommodated on a single lead without significantly increasing the planar area, thus managing manufacturing complexity.
Solution Approach 2:
The lead frame structure is designed to serve multiple functions: it provides electrical connection paths for power signals and simultaneously incorporates testing lands for wire connection verification. This multi-functionality integrates testing capability into the existing lead frame without requiring separate dedicated testing structures.
3Difficulty of detecting and measuring
If testing lands are insulated from the bulk of the lead, then different electrical paths are provided for testing, but the lead frame structure becomes more complex
Solution Approach 1:
The lead is segmented into distinct electrical zones: the bulk lead portion and the insulated testing land portions. This segmentation creates electrically isolated regions that enable different testing paths while maintaining the overall lead frame structure. The testing lands are separated from the bulk lead through insulation, allowing independent voltage measurement.
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
Enables effective testing of multiple wires connected on a single lead within a device package, ensuring reliable electrical connections and preventing open or short-circuited wire bonds, thereby improving the quality of semiconductor devices.
Implementation Method 1
a first testing land (141) provided on the bulk (140) of the lead (14), the first testing land (141) being electrically insulated from the bulk (140) of the lead (14) by an insulating layer (141a)
Implementation Method 2
applying onto said testing lands electrically conductive material (144) to provide an electrically conductive path between said stacked testing lands (141, 142) and the bulk (140) of the lead (14)
Implementation Method 3
the deposition of an insulating layer on a lead tip, by routing the layer on the lead outside the molded package area with a possible deposition of a conductive layer over the insulating layer
Data Source
AI summary
A method for use in manufacturing semiconductor devices such as, e.g., semiconductor power devices includes providing: a semiconductor die provided with bonding pads, a lead frame for the semiconductor die, a wire bonding layout including electrically conductive wires coupling bonding pads of the semiconductor die with leads in the lead frame. One or more bonding pads of the semiconductor die is/are coupled to a respective lead in the lead frame via a plurality of wires with a plurality of mutually insulated testing lands in the respective lead, so that the plurality of wires are coupled to respective testing lands. The electrical connection between such a bonding pad and the respective lead may be tested by testing the individual electrical connections between the bonding pad and the plurality of testing lands.