Interlocking Conductive Clips for IC Package Alignment
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Solution Overview
Problem
In integrated circuit packaging, conductive clips used to connect stacked semiconductor dies to a lead frame can become misaligned during the solder reflow process due to surface tension, leading to poor connections and increased costs.
Innovation Solution
The use of interlocking clips with complementary alignment features, such as channels and protrusions, ensures that the clips remain properly positioned during solder reflow, preventing relative movement and maintaining alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional clips without alignment features are used, then the device structure is simpler, but the clips become misaligned during solder reflow due to surface tension
Solution Approach 1:
The clip structure is segmented into multiple functional parts: a body portion, alignment features (protrusions and channels), and engagement features. This segmentation allows the alignment features to be integrated into the clip without significantly increasing overall complexity while ensuring proper positioning during solder reflow.
Solution Approach 2:
Alignment features (protrusions and channels) are pre-formed on the clips before the soldering process. These features preliminarily establish the correct spatial relationship between clips and prevent misalignment during the subsequent solder reflow process, eliminating the need for post-alignment adjustments.
2Manufacturing precision
If clips without alignment features are used, then manufacturing is easier, but misalignment leads to poor connections and increased costs
Solution Approach 1:
The manufacturing process is segmented into distinct steps: forming alignment features on clips, positioning clips on the substrate, and then performing soldering. This segmentation allows alignment features to be created using standard fabrication techniques without significantly complicating the overall manufacturing process.
Solution Approach 2:
Alignment features are preliminarily formed on clips during the clip fabrication process itself, before clips are positioned and soldered. This preliminary action ensures precise clip positioning is built into the clips, reducing the need for complex positioning fixtures or procedures during assembly.
3Reliability
If clips are secured during solder reflow, then connection reliability improves, but the solder reflow process becomes more complex
Solution Approach 1:
Alignment features are pre-formed on clips to automatically maintain proper positioning during solder reflow. This preliminary structural preparation eliminates the need for complex external fixtures, clamps, or active control systems during the soldering process, keeping the soldering process simple while ensuring connection reliability.
Solution Approach 2:
The alignment features on the clips themselves provide the securing function during solder reflow. The protrusions and channels create mechanical interlocking that self-maintains clip positioning without requiring external intervention, complex fixtures, or additional process steps during soldering.
Data Source
AI summary
An electronic device includes a lead frame, a first clip, a second clip, and a plurality of semiconductor devices. The first clip is stacked with the lead frame. The second clip stacked with the first clip and the lead frame. The second clip includes a first protrusion that engages the first clip and secures the second clip to the first clip. The semiconductor devices are conductively coupled to the lead frame via the first clip and the second clip.