Advanced Capacitors

Capacitors continue to represent a critical component in electronic devices utilized for electrical energy storage and switching.  Today’s capacitors needed in conjunction with advanced electronics, are facing limitations either in energy density, thermo-mechanical stability, and/or volume efficiency.  IMS expertise and innovation in thin films’ growth and characterization, material synthesis and processing, device conception, fabrication, and lab-on-chip integration has lead to the development of practical solutions that materialized into proven technologies and protected intellectual property (IP) ready to be embraced for a path to commercialization.

As an optimal solution, IMS team successfully managed to develop two distinctly different categories of advanced-capacitor materials and technologies, namely:

  • Extreme-temperature Ceramic Capacitor (ETCC)

  • Nano-particle Embedded Polymeric Matrix (NPPM) Capacitor

‚ÄčEach technology capitalizes on its unique advantages to provide the optimal and practical solution for users and integrators. 
 

Extreme-temperature Ceramic Capacitor (ETCC):

The ceramic–based capacitor technology aims at finding practical solutions to specific problems faced by industries requiring rugged instrumentation that would reliably function in an environment under extreme temperatures. The research team at IMS is developing dual-use thin film capacitors that can sustain operation at extreme low and high temperatures cycling (-200 oC to 350 oC). The device (capacitor) structure is made from a multilayer stack of high-temperature BN/BON thin dielectric layers and low cost internal metal electrodes such as aluminum (Al) and titanium (Ti).  Fabricated prototypes of compact and high energy density chip-capacitors (photos below) have exhibited stable and consistent performance, far superior to the temperature-limited (< 200 oC) leading sintering technologies.  The multilayered ETCC capacitors are suitable for applications in extreme temperatures environment, constituting prime candidates for high performance applications in aerospace industry, geothermal exploration, deep-well oil and gas drilling, and next generation automobiles and military vehicles.

Ti-based Al-based
Typical BN/BON layered capacitor chips (size: 1.5 cm x 1.7 cm)

While the performance specifications of devices representing this technology surpass those demanded by several industrial applications, especially in temperature endurance, the potential capacity of storage density can be attained only through implementation of complex multilayer device-scheme.  This is primarily due to the fact that the thin film strip of the individual dielectric layer has a relatively lower dielectric constant than that of the dielectrics used in the conventional capacitors. 
 

Nano-particle Embedded Polymeric Matrix (NPPM) Capacitor:

As a result of continued innovation to advance the state-of-the-art, IMS has initiated an aggressive technology integration program to develop high-power storage capacitors based on nanodielectrics with metallic nanoparticles (NPs) embedded in polymeric matrix materials (NPPM) to significantly enhance the dielectric constant to that of a supercapacitor category.

In general, available capacitors are either of low energy density, in terms of charge storage, or low power density, in terms of energy release.  By definition, a supercapacitor can functionally provide both aspects of high power density and high energy density in a relatively smaller size and weight form factor.  IMS nanodielectrics-based technology has the potential to increase the dielectric constant of the insulator material, which can easily enhance device capacitance by a factor of 50 over current devices.  In addition, the technology lends itself to an easier fabrication scheme, which can lower device cost by an estimated (20-60) %.

The mature technology will be best oriented for developing a unique high-energy (high-storage capacity) and high power density (fast discharge) capacitor.  Its insulator is an engineered nanodielectrics-based thin film composite material, based on nanoparticle-embedded polymer matrix (NPPM) with significantly larger dielectric constant (k) value.  The core of this approach is based on achieving high-k dielectric structures by embedding noble metals into low dielectric constant materials with proven high breakdown and low loss properties, using traditional thin film deposition techniques.  To create the high-k nanodielectrics thin film, two novel processing techniques are pursued: 

  • Laser Ablation

  • Wet Chemistry
     

Laser Ablation:

In the laser-based technique, the metal nanoparticles (NPs) are generated by laser ablation of the bulk metal in a liquid.  These NPs are then coated with a polymer that forms a composite after going through a few processing steps.  This composite is then spin-coated on metallic foil representing the first electrode.  A second metallic electrode is added to form the capacitor.  Embedding metal NPs in polymer matrix seems to be a very effective way to enhance the dielectric performance of the nanocomposite.  Consequently, the dielectric constant and hence the capacitance can be increased considerably until a threshold concentration is reached.  In addition, a uniform distribution of the inter-particle spacing is required to approach the optimal capacitance level.
 

Wet Chemistry:

The wet chemistry technique provides a unique approach to enhance the permittivity dielectric structure by embedding noble metal nanoparticles (NP) (either coated or uncoated with SiO2 core-shell) into low-k dielectric polymeric matrix (PM) with proven high-breakdown and low loss properties.  The dielectric constant can be tailored to reach the percolation threshold for maximum value.  Utilizing a polymer  capitalizes on its advantages in terms of higher processing ability, stability, mechanical flexibility, electrical breakdown strength, compatibility with several established electronics processing techniques, and its low-k.  NPPM capacitors exploiting such nanodielectrics materials can be fabricated using standard manufacturing processes to yield devices with reduced size and weight.  The lack of need for a bulky layer of dielectric permits the packing of plates with much larger surface area into a given size, resulting in high capacitance values in practical-sized packages.

In a simple comparison of solely capacitance values of IMS’s dielectric material with an equivalent thickness to those from established vendors, there is a clear indication of comparability and potentially having an edge considering all other specifications and cost.  The finished product can either be formed into a discrete component or an integrated (embedded) element using the traditional fabrication routine of IC-compatible devices. 
 

Product Comparison:

Manufacturer   Trade Name  Dielectric Material Thickness (µm) Capacitance  (nF/in3)
Hadco         

EmCap                 

Epoxy Resin/  100  2.1  
Hadco  BC2000 FR-4  50 0.5  
3M C-Ply Epoxy Resin/Barium Titanate 4-25 10-30  
DuPont HiK  Polyimide Core/Barium Titanate 25 0.5 
IMS  Laser Ablated(NPPM) NP-embedded Polymeric Matrix  10 1650
IMS Wet-Chemistry(NPPM) NP-embedded Polymeric Matrix  0.6 2.71

 

Anticipated Specifications:

Thickness (µm) Capacitance (µF) Voltage (V) Volume (cm³) Energy Density (µF/cm³)
1 9.8 100 37.3  264.1
20 0.5 1000 39.1 12.6

                                                       

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