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Home , Printed circuit board, Resistor

Embedded Applications and Implementation in MEMs and RF Devices

By Bruce Mahler Vice President Ohmega , Inc.

IMS 2017 olulu,niIMS 2017 Honolulu, Hawaii June 7, 2017 Thin Film Embedded • 1. Electrodeposited NiP thin film resistive material • 2. Standard subtractive PWB processing • 3. Surface or embedded resistors • 4. Mature technology (40+ years) • 5. Field Proven, Excellent Long Term Reliability

2 Why use Embedded Resistors? • Density improvement—free up board area or reduce board size with elimination of discrete resistors • Improved reliability with reduction in joints • Elimination of parasitic in dividers • Critical signal measurements to meet fast rise times and reduce signal delay • Placement of a termination resistor very close to the drive line • Very small element sizes with subtractive PCB print/etch • EMI improvement and improved fidelity in conjunction with a planar as an RC filter in MEMs microphone modules • Embedded or integral heaters at board level

3 Thin Film Resistive Material

4 NiP Sheet Resistivity Offerings

Sheet Material Resistivity Tolerance Typical Applications (Ω/□) (%) Series termination, impedance 10 3 matching, planar heaters 25 5 Series/ termination 40 5 resistors, power dividers, filters 50 5 100 5 Pull-up/pull-down resistors 250 10 High ohmic applications

5 Basic Design Overview

• Sheet resistivity, stated in per square is dimensionless • A square area of resistive material equals the sheet resistivity of material

Ω • 25 ohms per square ( ) sheet resistance ■ • Resistor value = sheet resistivity X ratio of element length to width 퐿 퐿 • 푅 = 푅 × ; where = 푛푢푚푏푒푟 표푓 푠푞푢푎푟푒푠 푁 푠 푊 푊 • For example:

• Sheet resistivity (Rs) = 25 Ω/□ • Length = 0.030” (30 mils) • Width = 0.015” (15 mil) Ω 30 푚푖푙푠 • 푅 = 25 × ∎ ∎ 15 푚푖푙푠 • 푅 = 50Ω

6 Sheet Resistivity (Rs) Adjustments for PTFE Substrates • of NiP to PTFE substrates results in a one time shift in nominal sheet resistivity: • 25 per square → 28 ohm per square • 50 ohm per square → 60 ohm per square • 100 ohm per square → 140 ohm per square • For designs requiring a PTFE , the modified sheet resistivity should be used when calculating resistor footprints.

7 Ohms Per Square

• Pull-up/down and termination resistors military/aerospace board

8 Ohms Per Square

• Sample Circuit 50 ohm per square on Duroid 6202PR

9 PCB Processing of NiP Resistive Conductive Material • Step 1: Apply to Laminate

10 PCB Processing of NiP Resistive Conductive Material • Step 2: Print and Develop Composite Image

11 PCB Processing of NiP Resistive Conductive Material • Step 3: Etch Unwanted Using Any Conventional Etchant (1st etch)

12 PCB Processing of NiP Resistive Conductive Material • Step 4: Etch Unwanted Resistive Material with Copper Sulfate Solution (2nd process)

13 PCB Processing of NiP Resistive Conductive Material • Step 5: Strip Photoresist

14 PCB Processing of NiP Resistive Conductive Material • Step 6: Apply Photoresist, Print and Develop Conductor Protect Image (2nd print)

15 PCB Processing of NiP Resistive Conductive Material • Step 7: Etch Away Copper Over the Designed Resistor Using a Selective Alkaline Etchant (3rd etch)

16 PCB Processing of NiP Resistive Conductive Material • Step 8: Strip Photoresist

17 Two Print Artwork PCB Processing

Artwork layout • NiP resistor processing consists of two prints: • 1st print – COMPOSITE image of conductors and resistors • 2nd print – RESISTOR DEFINE image of resistor elements

Composite (negative film) resistor define commonly used for or plane with most of the copper preserved.

COPPER PAD

Composite (negative film) conductor protect commonly used for signal plane

18 NiP Resistive Material in RF Applications • Provides greater packaging densities • Eliminates resistor assembly • Eliminates solder joints • Weight savings • Reduction in parasitic and • Excellent stability beyond 70 GHz • Low profile copper for low insertion loss

19 NiP Resistive Material in RF Applications

20 Performance Benefit of NiP Planer Resistor • Reduction in parasitic and inductance compared to surface mount components. • Reduce metal-to-metal transitions associated with chip resistors • Reduce vias on critical nets

21 NiP Resistors in Applications

22 NiP Resistors in Microwave Applications

0.026” x 0.0145

Enlargement of a four-up array 16-way power divider with 50 /sq NiP resistors

23 NiP Resistor Designs in Space Applications

NiP resistors in microwave application for Layer stack up. Globalstar .

24 Globalstar Antenna – NiP Resistor Inner Layer

25 NiP Resistor Designs in Military/Aerospace Applications

Active Phased Array Antenna

26 NiP Resistive Material in R-Cards and Absorbers • Can be laminated to a variety of substrate materials with different permittivities • Create repetitive, planar patterns using standard techniques (subtractive print/etch) • Cost reduction • Weight savings (reduced thicknesses) • Increased bandwidth and improved performance covering wider angles of incidence

27 NiP Resistors in RF Electromagnetic Absorbers and R-cards

28 NiP Resistors in RF Electromagnetic Absorbers and R-cards

29 NiP Resistive Conductive Material in Sensors • Increased PCB density (small element sizes) • Reduced PCB thickness (eliminate SMT-R) • Reduced assembly (resistor built into PCB) • Improved Reliability (elimination of solder joints) • Improved electrical performance (reduced EMI) • Cost savings (replacement of discrete SMT-R)

30 NiP Resistors in MEMs Microphone Sensor

31 NiP Resistors in MEMs Microphone Sensor

32 NiP Resistors in MEMs Microphone Sensor

2.5” Consumer

3.5”

MEMs Microphones

33 NiP Resistor Reliability

• Researchers at Alcatel Bell tested NiP resistors for broadband (45 MHz-5 GHz) telecom applications to compare the reliability of NiP resistors to 0805 discrete thick film chip resistors rated at 125mW. The NiP resistors were as good as, or better than, the chip resistor in all performed tests. Measured ΔR Thick Film Chip Type of Test Ohmega Specifications (Alcatel Tested) (0805) After 21 days: • 0.22% for 25 Ohm/sq. • 0.07% for 100 Ohm/sq. Humidity Test After 10 days: • 0.10% for 250 Ohm/sq. After 56 days: Temp: 40°C • 0.5% for 25 Ohm/sq. After 56 days: • 1.0% for 100 Ohm/sq. ≤ ± 1.5% RH: 93% • 0.74% for 25 Ohm/sq. • 0.14% for 100 Ohm/sq. • 0.22% for 250 Ohm/sq. After 100 Cycles Thermal Cycling After 25 Cyles • - 0.03 % for 25 Ohm/sq. High: 125°C • - 0.5% for 25 Ohm/sq. ≤ ± 25% • 0.03 % for 100 Ohm/sq. • 1% for 100 Ohm/sq. Low: -25°C • - 0.08 % for 250 Ohm/sq. After 100 Hrs. Unbiased Aging • 0.10% for 25 Ohm/sq. Not specified Not specified 125°C • 0.08% for 100 Ohm/sq. • - 0.13% for 250 Ohm/sq.

Solder Float • - 0.02% for 25 Ohm/sq. • 0.5% for 25 Ohm/sq. 260°C • 0.01% for 100 Ohm/sq. ≤ ± 25% • 1% for 100 Ohm/sq. 20 seconds • - 0.01% for 250 Ohm/sq.

34 NiP Resistor Reliability

• Dassault Electronique (Thales) did a 2 year study of NiP resistors for an active phased array antenna (X-band). The resistors were constructed on Rogers RT Duroid® 6002 substrate and fusion bonded inside a multilayer package. The NiP resistors were selected over printed polymer ink and chip resistors. Method Result Etching Tolerance (%) 5 Minimum Resistor Width (um) 200 Tolerance After Fusion Bonding (%) 7 Influence of NiP Layer on Microwave Negligible Properties Thermal Cycle (% ΔR) • 2% • -55°C to 125°C, 500 cycles • 3% Thermal Coefficient of Resistance (% ΔR) • Microstrip +/- 2% • -55°C to 125°C • Stripline +/- 3% Power (mW) 300 2-Port Power Divider Environmental Stress Test (% ΔR) • Thermal Cycle: -55°C to 125°C, 500 cycles Negligible • High Temperature Storage: 125°C, 500 hours • Static Humidity: 40°C, 95% RH, 40 days • Salt Spray: 48 hours 35 NiP Resistor Reliability

• NiP for -free assembly. Highly Accelerated Thermal Shock Test (HATS) • -40°C to 145°C • 1000 cycles • 10.85 minutes per cycle

Resistor Network % ΔR 15 Coupons per Resistor network 1 0.20 2 0.15 3 0.20 4 0.17

36 NiP Resistor Reliability • Stability over long term continuous operation

37 NiP Resistor Reliability

• Application shows a heater used to bring the X-Ray Spectrometer (XRS) and pre-amplification electronics to -50 degrees Celsius in the Mars Beagle 2 Lander.

38 Summary • NiP thin film resistive material used extensively in RF and MEMs designs • Improved package densities • Improved electrical performance • Improved reliability • Standard subtractive PCB processing • Growing applications in IC packaging, IOT sensor technologies, 5G and DDR4 memory devices

39 OHMEGA TECHNOLOGIES, INC.

4031 ELENDA STREET

CULVER CITY, CA 90232-3799

PHONE: (310)559-4400

FAX: (310)837-5268

WEB SITE: http://www.ohmega.com

Copyright  2017 Ohmega Technologies, Inc.

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