Leadless Semiconductor Package Metal Die Attach
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Solution Overview
Problem
Conventional die attach solutions using metal particle filled polymers face significant thermal and electrical resistance issues, which are exacerbated by the high cost and temperature-induced stresses of solder die attach methods, limiting their effectiveness in compact, high-integration electronic systems.
Innovation Solution
A leadless semiconductor package is developed with an electroplated metal die attach layer that directly contacts the semiconductor die's back side metal layer and the substrate, eliminating voids and stress-related issues, while providing improved thermal and electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal particle filled polymer die attach adhesive is used, then mechanical attachment is provided, but thermal and electrical resistance increases
Solution Approach 1:
The patent replaces expensive solder with a cost-effective metal particle filled polymer adhesive that provides adequate mechanical attachment while eliminating the need for expensive solder materials and complex reflow processing
Solution Approach 2:
The die attach adhesive uses a composite formulation combining polymer matrix with metal particles to achieve both mechanical bonding and improved thermal/electrical conductivity, balancing structural requirements with heat and electricity dissipation needs
2Reliability
If solder die attach is used, then good thermal and electrical conductivity is achieved, but cost increases and temperature induced stresses occur
Solution Approach 1:
The patent substitutes expensive solder with a more economical metal particle filled polymer adhesive, reducing material costs and eliminating the need for expensive inert reflow processing while achieving sufficient thermal and electrical performance
Solution Approach 2:
The invention changes the operating temperature parameters by eliminating high-temperature solder reflow processing, using instead lower temperature curing processes that avoid temperature-induced thermal stresses on the semiconductor die and metal interconnect
3Reliability
If solder die attach is used, then electrical contact is provided, but voiding issues occur due to Sn-Cu intermetallic formation
Solution Approach 1:
The patent replaces solder with a polymer-based metal particle filled adhesive that does not form problematic intermetallic compounds, eliminating voiding issues and ensuring reliable electrical contact without the manufacturing defects associated with solder reflow processes
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
The electroplated metal die attach layer enhances thermal management and reduces electrical resistance, offering a cost-effective solution for compact, high-integration electronic systems without the stress-related limitations of solder die attach methods.
Implementation Method 1
the electroplated metal die attach layer enhances thermal management
Implementation Method 2
reduces electrical resistance
Data Source
AI summary
A leadless packaged semiconductor device includes a metal substrate having at least a first through-hole aperture having a first outer ring and a plurality of cuts through the metal substrate to define spaced apart metal pads on at least two sides of the first through-hole aperture. A semiconductor die that has a back side metal (BSM) layer on its bottom side and a top side with circuitry coupled to bond pads is mounted top side up on the first outer ring. A metal die attach layer is directly between the BSM layer and walls of the metal substrate bounding the first through-hole aperture that provides a die attachment that fills a bottom portion of the first through-hole aperture. Bond wires are between metal pads and the bond pads. A mold compound is also provided including between adjacent ones of the metal pads.