Laminate Transformer Package Assembly With Lower AC Winding Loss
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Solution Overview
Problem
Existing semiconductor device packages with integrated transformers face challenges such as high manufacturing costs, low efficiency, and increased die costs due to complex manufacturing processes and AC winding losses.
Innovation Solution
A method involving the formation of a package substrate with isolated conductive leads and a laminate transformer with integral magnetic material, where the transformer is mounted using a non-conductive die attach material, and electrical connections are made between the semiconductor die and the transformer using wire bonds or ribbon bonds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If magnetic sheets are mounted to the laminate transformer using die attach material, then the transformer can be assembled within the semiconductor package, but AC winding losses increase due to spacing between magnetic sheets and coils
Solution Approach 1:
The magnetic material is integrated directly into the laminate substrate structure, merging the magnetic sheets with the transformer coils. This eliminates the need for separate die attach material layers between the magnetic sheets and coils, thereby removing the spacing that causes AC winding losses while maintaining assembly feasibility
Solution Approach 2:
The patent uses asymmetric placement of magnetic material only where needed around the coils, rather than uniform spacing. The magnetic material is positioned adjacent to the coils on one side while leaving other sides open or with minimal material, optimizing magnetic coupling without requiring symmetric spacing that would increase losses
2Adaptability or versatility
If an on-die transformer is formed directly on the semiconductor die, then device integration increases, but manufacturing cost increases and transformer efficiency decreases
Solution Approach 1:
The transformer is segmented from the semiconductor die and placed on a separate laminate substrate. This allows the transformer to be manufactured using standard PCB techniques rather than specialized semiconductor processes, reducing manufacturing costs while maintaining high integration within the final package
Solution Approach 2:
The laminate substrate acts as an intermediary carrier between the semiconductor die and the transformer. It provides a platform for mounting the transformer with proper spacing and electrical isolation, enabling high integration without requiring direct formation on the die surface
3Adaptability or versatility
If multiple die attach deposition and thermal cure steps are used to assemble magnetic sheets and laminate, then the transformer can be integrated, but manufacturing complexity and time increase
Solution Approach 1:
The magnetic material is merged with the laminate substrate in a single manufacturing step rather than being added separately. This eliminates multiple die attach deposition and thermal cure steps, reducing manufacturing process complexity and time while achieving the same integration result
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 reliable and robust semiconductor device package with improved efficiency and reduced costs, as the laminate transformer with integral magnetic material minimizes AC winding losses and simplifies the assembly process.
Implementation Method 1
a transformer having coils isolated from one another by a core of dielectric material, but electromagnetically coupled to one another
Implementation Method 2
a transformer having coils isolated from one another by a core of dielectric material, but electromagnetically coupled to one another
Data Source
AI summary
A described example includes: a package substrate including a mounting pad, at least one die pad, a first set of conductive leads, and a second set of conductive leads spaced from the first set of conductive leads; a semiconductor die mounted to the at least one die pad with a first die attach material; a laminate transformer with integral magnetic material mounted on the mounting pad with a second die attach material; first electrical connections of wire bonds or ribbon bonds between the bond pads of the semiconductor die and the first set of conductive leads; second electrical connections of wire bonds or ribbon bonds between the bond pads of the semiconductor die and the laminate transformer with integral magnetic material; and mold compound covering the electrical connections, the semiconductor die, the laminate transformer with integral magnetic material and portions of the package substrate.