Wire-Bonded Lead Frame Inductors for Compact IC Packages
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Solution Overview
Problem
Integrated circuits (ICs) face challenges in providing sufficient inductance for internal switched voltage regulators without increasing the size or complexity of the IC package, as external inductors consume valuable space and add height, while internal inductors complicate fabrication and increase costs.
Innovation Solution
The use of wire-bonded lead frames to form integrated inductors within the IC package, where a lead frame with adjacent leads is coupled by wire bonds to create a conductive coil, optionally surrounded by a magnetic overmold material to enhance inductance, allowing for compact and cost-effective inductor packages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external inductor is used for the voltage regulator, then sufficient inductance can be achieved, but the IC package area and height increase
Solution Approach 1:
The patent combines the inductor with the lead frame structure, integrating the inductor leads with the lead frame leads. This merging eliminates the need for separate external inductor components while achieving sufficient inductance, thereby reducing IC package area consumption.
Solution Approach 2:
The lead frame serves multiple functions: it provides mechanical support for the die, provides electrical interconnects, and forms the inductor coil structure. This multi-functionality eliminates the need for separate external inductor components, reducing both area and height of the IC package.
2Area of stationary object
If an internal inductor is formed within the package substrate or die, then IC package area is conserved, but fabrication complexity and cost increase
Solution Approach 1:
The inductor is merged with the lead frame structure using standard lead frame fabrication processes. This approach avoids the need for complex thin-film inductor fabrication processes that would be required if the inductor were formed directly within the package substrate or die.
Solution Approach 2:
The lead frame structure serves itself by forming the inductor coil using its own leads and wire bonds. This self-service approach eliminates the need for separate inductor fabrication processes, reducing overall fabrication complexity and cost.
3Reliability
If a land-side inductor is used, then inductance is provided, but the overall height of the IC package increases
Solution Approach 1:
The inductor coil is formed in a planar configuration within the lead frame plane, utilizing the lateral dimensions rather than extending vertically. This dimensional approach allows sufficient inductance to be achieved without increasing the overall height of the IC package.
4Reliability
If more leads are coupled with wire bonds to form the inductor coil, then inductance increases, but fabrication time and cost increase
Solution Approach 1:
The patent uses a sufficient number of wire bonds to achieve the required inductance without over-engineering the coil structure. This partial action approach achieves adequate inductance performance while controlling fabrication complexity and cost.
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 provides a compact, cost-effective method to achieve the necessary inductance for IC packages, reducing space consumption and fabrication complexity while enhancing inductance and quality factor through the use of wire-bonded lead frames and magnetic materials.
Implementation Method 1
a lead frame with adjacent leads is coupled by wire bonds to create a conductive coil
Implementation Method 2
optionally surrounded by a magnetic overmold material to enhance inductance
Data Source
AI summary
Inductor packages employing wire-bonds over a lead frame to form integrated inductor(s), and related integrated circuit (IC) packages and fabrication methods. The inductor package includes one or more integrated inductors each formed from leads of a lead frame coupled together in a pattern through wire bonds to foil a coil(s). An overmold material is formed over the lead frame with the coil(s) formed from the wire-bonded leads to form the inductor package. The overmold material can include a magnetic material to further increase the inductance of the integrated inductor(s). The inductor package can be mounted to a package substrate of an IC package to provide an inductor(s) for a circuit in the IC package. By using a lead frame to form an inductor package, fabrication processes used to form lead frames can also be used to form the inductor package as a less complex, lower cost manufacturing method.