LED Components Direct Die Attach to Lead Frame
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Solution Overview
Problem
Conventional Light Emitting Diode (LED) components using lead frames require wire bonding for electrical connection, which increases costs and complexity, and the mechanical flexibility of low-cost plastics like silicone used in lead frames complicates direct die attachment.
Innovation Solution
The LED component features a lead frame with a plastic cup where the LED die is directly attached to the metal anode and cathode pads using a solder layer, eliminating the need for wire bonds and enhancing robustness and compactness by configuring the metal pads and plastic cup to facilitate direct electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonding is used for electrical connection in LED components, then electrical connectivity is achieved, but manufacturing cost and device complexity increase
Solution Approach 1:
The patent removes the wire bonding step from the LED component manufacturing process. Instead of using wire bonds to connect the LED die to the lead frame, the invention directly attaches the LED die to the lead frame using a die attach layer, thereby eliminating the intermediate wire bonding complexity while maintaining electrical connectivity
Solution Approach 2:
The patent combines the electrical connection function with the mechanical attachment function into a single die attach layer. This layer simultaneously provides mechanical support and electrical conductivity, merging what were previously separate functions (wire bonding for electrical connection and die attach for mechanical support) into one integrated solution
2Ease of manufacture
If low-cost plastics like silicone are used in lead frames, then manufacturing cost is reduced, but mechanical flexibility complicates direct die attachment
Solution Approach 1:
The patent modifies the parameters of the die attach layer to compensate for the flexibility of silicone lead frames. By adjusting the thickness, composition, and bonding characteristics of the die attach layer, the invention achieves reliable die attachment despite the mechanical flexibility of the low-cost silicone material
Solution Approach 2:
The patent uses a composite die attach layer that combines materials with different properties to achieve both mechanical adhesion and electrical conductivity. This composite approach allows the die attach layer to accommodate the flexibility of silicone while providing stable electrical connections
3Device complexity
If direct die attachment is implemented without wire bonds, then manufacturing cost and device complexity are reduced, but electrical connection reliability may be compromised
Solution Approach 1:
The patent introduces a die attach layer as an intermediary between the LED die and the lead frame. This intermediate layer serves dual purposes: providing mechanical attachment and ensuring electrical conductivity, thereby maintaining connection reliability while eliminating the need for wire bonds
Solution Approach 2:
The patent applies local quality enhancement by ensuring the die attach layer has high electrical conductivity specifically at the contact points with the lead frame pads. The layer is designed with optimized material composition and thickness to provide excellent electrical properties where needed while maintaining overall structural integrity
4Ease of manufacture
If metal pads are configured for direct electrical connection, then wire bonding is eliminated, but pad non-coplanarity challenges direct attachment
Solution Approach 1:
The patent employs a die attach layer with sufficient thickness and compliance to accommodate variations in pad height and non-coplanarity. The layer can deform elastically to conform to the actual pad geometry, allowing successful attachment even when pads are not perfectly coplanar, thus maintaining manufacturing simplicity without sacrificing alignment precision
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 reduces costs and improves reliability by eliminating wire bonding and allowing for more compact designs, while the die attach layer's composition and thickness ensure effective electrical connections even with non-coplanar metal pads, enhancing the structural rigidity and thermal performance of the LED components.
Implementation Method 1
a die attach layer that directly electrically connects the outer face of the anode contact to the exposed portion of the metal anode pad and directly electrically connects the outer face of the cathode contact to the exposed portion of the metal cathode pad
Implementation Method 2
The die attach layer may include a solder layer, which may facilitate the direct electrical connection
Data Source
AI summary
A Light Emitting Diode (LED) component includes a lead frame and an LED that is electrically connected to the lead frame without wire bonds, using a solder layer. The lead frame includes a metal anode pad, a metal cathode pad and a plastic cup. The LED die includes LED die anode and cathode contacts with a solder layer on them. The metal anode pad, metal cathode pad, plastic cup and/or the solder layer are configured to facilitate the direct die attach of the LED die to the lead frame without wire bonds. Related fabrication methods are also described.