Interdigital Transducers (IDTs): Substrate Thickness 0.2-1.0 mm

Component Specifications

Definition

Interdigital Transducers (IDTs) are patterned electrode structures fabricated on piezoelectric substrates, typically using photolithography. They consist of interleaved metal fingers that generate and detect Surface Acoustic Waves (SAWs) when alternating electrical signals are applied. In SAW filters, IDTs serve as both transmitters and receivers of acoustic waves, enabling precise frequency selection and signal processing through constructive and destructive interference patterns. Their design parameters (finger width, spacing, overlap length) directly determine the filter's center frequency, bandwidth, and insertion loss characteristics.

Working Principle

IDTs operate on the inverse piezoelectric effect. When an alternating voltage is applied to the interdigitated electrodes on a piezoelectric substrate, it creates periodic mechanical strains that generate Surface Acoustic Waves (SAWs) propagating along the substrate surface. Conversely, incoming SAWs create electrical signals through the direct piezoelectric effect. The periodic finger structure acts as a spatial sampling mechanism, with the finger pitch determining the resonant frequency through the relationship f = v/λ, where v is the SAW velocity and λ is the acoustic wavelength (typically twice the finger pitch).

Materials

Substrate: Lithium Niobate (LiNbO3), Lithium Tantalate (LiTaO3), Quartz (SiO2). Electrodes: Aluminum (Al), Aluminum-Copper alloy (Al-Cu), Gold (Au) with chromium/titanium adhesion layers. Passivation: Silicon Nitride (Si3N4), Silicon Dioxide (SiO2).

Technical Parameters

Parameter	Typical range	Notes & selection driver
Aperture	10-100 λ
Bandwidth	0.1% to 20% of center frequency
Finger Pairs	10-200 pairs
Insertion Loss	1-6 dB
Electrode Pitch	0.5-50 μm
Center Frequency	10 MHz to 3 GHz
Substrate Thickness	0.2-1.0 mm
Temperature Coefficient	-30 to -50 ppm/°C

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

IEEE 176, IEC 62276, MIL-STD-883

Parent Products

This component is used in the following industrial products

Filter (Bandpass/SAW)

An electronic component that selectively passes signals within a specific frequency range while attenuating others, used in receiver circuits.

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Engineering Analysis

Risks & Mitigation

Electromigration under high current density
Acoustic fatigue leading to electrode delamination
Temperature-induced frequency drift
Contamination affecting piezoelectric properties
Electrostatic discharge damage during handling

FMEA Triads

Trigger: Electromigration in narrow electrodes
Failure: Increased insertion loss, complete electrical open
Mitigation: Use aluminum-copper alloys, optimize current density, implement redundant electrode structures

Trigger: Substrate contamination during fabrication
Failure: Reduced Q-factor, spurious responses
Mitigation: Cleanroom processing, proper packaging, hermetic sealing

Trigger: Thermal expansion mismatch
Failure: Electrode cracking, frequency drift
Mitigation: CTE-matched materials, temperature compensation designs, thermal management

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

±0.1% frequency tolerance, ±0.5 dB insertion loss variation, ±5° phase deviation

Test Method

Network analyzer measurements (S-parameters), probe station testing, temperature cycling (-40°C to +85°C), accelerated life testing

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

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Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

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Manufacturers of Interdigital Transducers (IDTs)

Manufacturer profiles associated with Interdigital Transducers (IDTs).

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Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review

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Frequently Asked Questions

What determines the operating frequency of an IDT?

The operating frequency is primarily determined by the finger pitch (center-to-center distance between adjacent fingers) and the acoustic velocity of the substrate material, following the relationship f = v/(2p), where v is SAW velocity and p is finger pitch.

Why are aluminum electrodes commonly used in IDTs?

Aluminum offers low electrical resistance, good adhesion to piezoelectric substrates, compatibility with semiconductor fabrication processes, and appropriate acoustic impedance matching to minimize reflections at electrode boundaries.

What are the main performance limitations of IDTs?

Key limitations include insertion loss (energy conversion inefficiency), power handling capacity (due to acoustic nonlinearities), temperature sensitivity (frequency drift), and fabrication tolerances affecting yield at high frequencies.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Interdigital Transducers (IDTs)