Leadframe Trace Protection Layer for IC Packaging
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Solution Overview
Problem
Current integrated circuit packaging systems face challenges in reducing costs, improving efficiencies, and enhancing performance due to rising material costs and competitive pressures, with existing methods failing to provide effective solutions for complex semiconductor chip packaging.
Innovation Solution
The method involves providing a pre-plated leadframe with contact protrusions and protective pads, forming contact pads and traces through etching, applying a trace protection layer, removing the protective pads to expose the contact pads, and depositing external connectors directly on the pads without intervening plating, using a backgrinding process to ensure a strong solder joint and prevent warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional plating processes are used on leadframes, then electrical interconnects are formed, but material costs increase and manufacturing complexity increases
Solution Approach 1:
The leadframe is pre-plated with a copper pattern before die attachment and wire bonding. This preliminary plating action eliminates the need for subsequent plating steps, reducing manufacturing complexity while ensuring reliable electrical interconnects are already in place before packaging operations begin
Solution Approach 2:
The plating process is extracted and performed separately as a preliminary step on the leadframe itself, rather than being integrated into the main packaging process flow. This separation allows the leadframe to be prepared in advance with the required copper pattern, simplifying the overall manufacturing process
2Strength
If multiple plating layers are applied to ensure strong solder joints, then joint strength improves, but manufacturing time increases and process complexity increases
Solution Approach 1:
Multiple plating layers (copper pattern, solder resist, solder mask) are applied in advance to the leadframe before packaging. This preliminary multi-layer plating ensures strong solder joints are already established, eliminating the need for time-consuming multi-step plating during production and improving manufacturing efficiency
Solution Approach 2:
Multiple protective and conductive layers are merged into a single integrated plating structure on the leadframe. The copper pattern, solder resist, and solder mask are combined in one preliminary plating process, achieving strong solder joints without requiring separate plating operations during manufacturing
3Reliability
If protective pads are used during processing, then trace protection is provided, but additional material costs and processing steps are required
Solution Approach 1:
The solder resist layer serves multiple functions: it protects the copper traces from oxidation and short circuits during processing, provides a base for the solder mask, and prevents solder from bridging to unwanted areas. This multi-functional layer eliminates the need for separate protective pads and reduces processing steps
Solution Approach 2:
The protective function previously requiring separate protective pads is merged into the solder resist layer. This consolidation eliminates additional materials and processing steps while maintaining comprehensive trace protection throughout the manufacturing process
4Reliability
If external connectors are deposited on contact pads, then electrical connection is established, but material costs and manufacturing complexity increase
Solution Approach 1:
The contact pads are pre-formed with the copper pattern during the preliminary plating stage. This preliminary formation of contact pads eliminates the need for subsequent deposition processes, reducing manufacturing complexity while ensuring reliable electrical connections are already in place before final assembly
Solution Approach 2:
The contact pad formation process is extracted and performed as part of the preliminary leadframe preparation. This separation allows contact pads to be created in advance with the required copper pattern, eliminating the need for additional deposition steps during packaging manufacturing
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 approach results in a cost-effective and reliable integrated circuit packaging system with improved solder joint strength and reduced warpage, enhancing manufacturing efficiency and performance by matching the thermal expansion coefficients of materials and ensuring uniformity across the trace protection layer.
Implementation Method 1
forming a contact pad and traces by etching the pre-plated leadframe
Implementation Method 2
using a backgrinding process to ensure a strong solder joint and prevent warpage
Data Source
AI summary
An integrated circuit packaging system and method of manufacture thereof including: providing a pre-plated leadframe having a contact protrusion and a protective pad on the contact protrusion; forming a contact pad and traces by etching the pre-plated leadframe; applying a trace protection layer on the contact pad, the traces, and the protective pad; removing the protective pad and a portion of the trace protection layer for exposing the contact pad; and depositing an external connector directly on a surface of the contact pad.