1. RHC 2512 Size 2 Watt Chip Training Module

2. Introduction Purpose Objectives Content Learning Time
Provide a basic overview of Stackpole’s RHC series 2512 size 2 watt surface mount resistors
Objectives
Discuss current solutions and their limitations
Explain the RHC’s unique materials, design and processes
Show how the RHC performs vs. standard 2512 size thick film chips
Content
10 pages
Learning Time
10 minutes
Welcome to the Stackpole RHC Training Module. In this module, the function, features, and applications of SEI’s RHC resistors will be presented, and will show how the RHC is characterized.

3. Current High Power SMD Resistor Solutions
SMD wirewounds – are inherently inductive, and are not fusible unless specifically ordered that way; SMD wirewounds will also be much larger, taller, heavier, and more costly than the RHC
Parallel combinations of standard flat chips, or melfs – requires more parts, placements, and solder joints increasing costs, product weight, and decreasing overall reliability.
The RHC offers a 2 watt power rating in a 2512 size chip package. No other currently available solution provides the same power capability in this size package.

4. RHC Design, Materials, and Structure
Unique resistive element
Protective coating
Outer plating
Substrate
Inner plating
Inner electrode
Materials
Remark
Substrate
Alumina 96％
Bottom Electrode
2512 Standard ： 0.7土0.2 mm
TSR1S series　： 2.2土0.2 mm
Resistive Element
RuO2
Inner electrode
Ag/Pd
Protective coat
Glass・Special
Inner Plating Ni
Outer Plating Ｓn
Compared to standard thick film chips the RHC is designed differently, uses some different materials, and has different manufacturing processes. These three aspects are chosen to maximize the power handling of the part while minimizing the overall heat retained within the part.

5. Unique Glass and Passivation Overcoat
RHC 2512（2512-2Ｗ）
Standard chip（2512-1Ｗ）
Passivation materials chosen to optimize heat transfer to ambient air
Standard chips have low cost materials chosen which tend to hold the heat into the resistor
The RHC offers a 2 watt power rating in a 2512 size chip package. No other currently available solution provides the same power capability in this size package.

6. RHC Unique Manufacturing Process
Standard chip（2512-1Ｗ）
Reduced hot spot temperature
Inner Structure
Unique Resistive
element
The RHC uses a unique calibration process that spreads out and minimizes the effective hot spot temperatures.
Standard chips have a single intense hot spot in the middle of the resistor.
The RHC is trimmed to value in a unique proprietary manner that creates lower hot spot temperatures compared to standard parts. The heat is distributed much more evenly across the entire resistor element.

7. RHC Bottom Termination Design
The larger bottom terminations disperse heat to the circuit board more efficiently.
Standard chips have standard terminations for low cost and compatibility with existing industry standards.
RHC（2512-2Ｗ）
Standard chip（2512-1Ｗ）
Superior heat transfer to PCB
Larger
Bottom
Terminations
Temp profile of Chip Surface
Leveled Temperature Profile（Temp decrease at heat spot）
The end result of these unique features is that the RHC will run 30 to 40 degrees C cooler than a standard chip under identical conditions as shown on the following slide

8. Temperature Rise
RMC vs RHC

9. 2 Watt Resistor Comparison
Two Chips or Melfs
Surface Mount Wirewound
SEI RHC Series
Technology
Metal Film / Thick Film
Molded Wirewound
Thick Film
Package Dimensions (in.)
.248 L x .300 W x .021 H
.435 L x .240 W x .180 H
.248 L x ..126W x H
Inductance
Very Low
High
Short Time Overload Capability,
5 Sec pulse
10 watts
50 Watts
18 Watts
Resistance Range
Mohm
Kohm
0.1 ohm – 1 Mohm
Placements / Mounting
Two 2512 size chips
Single 4424 size part
Single 2512 size chip
Cost
Lowest
Highest
Low
Reliability
Good
Better
Board Space Used
Medium
Largest
Smallest
The RHC clearly offers the best combination of electrical performance, reliability, and cost. The two chip solution uses twice the board space as well as the other challenges of using multiple parts for a single need. The SMD wirewound is larger, more costly, and has higher inductance.

10. Future Trends
The unique features of the RHC should also provide improved power handling for smaller chip sizes.
RHC 2010 and RHC 1206 are currently being researched.
Some of the same features may also improve power handling for thin film resistors
Stackpole has a wide offering of power resistors to provide the optimal solution for a given application. The requirements for resistance, TCR, tolerance, power, pulse handling, size and cost will determine which series to choose

11. Summary
The RHC is a thick film 2512 size chip resistor capable of dissipating 2 watts, at 70C with only the recommended solder pads and no air movement or additional heat sinking of any kind required.
It is passivated in such a way that heat is more efficiently released to the ambient air.
It’s unique method of calibration to resistance value minimizes the overall hot spot temperature and helps spread the heat generated over the entire width of the resistor.
It has larger bottom terminations to help more efficiently transfer heat from the resistor to the PCB.
It has short time overload handling that is 80% better than the equivalent standard thick film chip.
It is an inherently non-inductive, fusible, relatively small, light, and inexpensive solution for a 2 watt power requirement.
With the proliferation of power electronics in nearly all market segments, high power SMD resistors are becoming more commonplace. Stackpole is committed to providing a wide range of power resistive solutions to meet the needs of this growing market