LED Package Insulating Film Prevents Silver Paste Short Circuits
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Solution Overview
Problem
Conventional LED modules face yield reduction due to short-circuits caused by silver paste coming into contact with wire bonding pads during LED chip arrangement.
Innovation Solution
An LED module design featuring a substrate with a conductive layer, insulating film, and strategically positioned wire bonding portions to prevent silver paste from reaching the wire bonding areas, ensuring electrical isolation and increasing yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If LED chips are arranged using silver paste, then the LED chips can be securely bonded to the substrate, but the silver paste may come into contact with the wire bonding pad causing short-circuits
Solution Approach 1:
An insulating film is introduced as an intermediary layer between the silver paste and the wire bonding pad. This insulating film allows the silver paste to maintain bonding strength with the LED chip while preventing electrical contact with the wire bonding pad, thus resolving the short-circuit issue without compromising bonding strength.
Solution Approach 2:
The wire bonding pad is divided into multiple regions: a first region for wire bonding, a second region for LED chip bonding, and a third region that is insulated from both. This segmentation allows the silver paste to bond to the second region while the insulating film prevents contact with the first region, eliminating the short-circuit risk while maintaining bonding functionality.
2Ease of operation
If the wire bonding pad is made larger to accommodate wire bonding, then wire bonding is easier, but the risk of silver paste contact increases
Solution Approach 1:
The wire bonding pad is segmented into distinct functional regions with insulating barriers. The first region accommodates wire bonding operations, while the third region provides an insulated area that prevents silver paste from causing short-circuits, thus maintaining ease of wire bonding while reducing short-circuit risk.
Solution Approach 2:
The insulating film acts as a mediator that allows the wire bonding pad to be larger for ease of operation while preventing the harmful effect of silver paste contact. The insulating film enables the pad structure to accommodate both wire bonding and LED chip bonding without direct electrical contact between them.
3Productivity
If the layout is optimized to prevent short-circuits, then yield increases, but the design complexity increases
Solution Approach 1:
The layout is segmented into standardized regions (first region for wire bonding, second region for LED chip bonding, third insulated region) that can be systematically applied across multiple LED modules. This segmentation provides a repeatable pattern that increases yield through consistency while managing complexity through modular design.
Solution Approach 2:
The insulating film is formed in advance during the substrate preparation stage, before wire bonding and LED chip mounting operations. This preliminary action establishes the electrical isolation structure beforehand, simplifying subsequent assembly operations and reducing the risk of short-circuits, thereby increasing yield without significantly increasing overall process complexity.
Data Source
AI summary
An LED module includes: a substrate including main, rear, and bottom surfaces; a first light emitting element disposed on the main surface; a conductive layer formed on the substrate and electrically coupled with the first light emitting element; a first conductive bonding layer interposed between the first light emitting element and the conductive layer; a main surface insulating film formed on the main surface and covering a portion of the conductive layer; and a first wire, wherein the main surface and the rear surface face opposite directions, the bottom surface connects long sides of the main and rear surfaces, the conductive layer includes a first wire bonding portion where the first wire is bonded, and the main surface insulating film includes a first insulating portion including a portion interposed between the first light emitting element and the first wire bonding portion when viewed in a thickness direction of the substrate.