IRC CHP Series Handbook
TT electronics
IRC - Wirewound & Film Technologies Division
736 Greenway Road
PO Box 1860
Boone, NC 28607 USA
1-828-264-8861
March 2003
CONTENTS
1.0 INTRODUCTION
1.1
1.2
Product History
Product Description
2.0 PRODUCT MANUFACTURE, STRUCTURE, AND OUALITY CONTROL
2.1
2.2
Manufacture and Structure
Product Quality Control
3.0 PRODUCT ELECTRICAL, ENVIRONMENTAL, AND MECHANICAL
CHARACTERISTICS
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
3.10
3.11
Product Specifications
CHP Part Number Description
Power Derating
Surge Rating
Performance Characteristics
Product Dimensions
Recommended Solder Pad Dimensions
Soldering Methods
High Frequency Characteristics
Flammability
Thermal Performance
4.0 PRODUCT RELIABILITY ASSURANCE PROGRAM
4.1
4.2
Conformance Test Program Summary
Standard Test Conditions and Acceptance Criteria
5.0 PACKAGING
Appendix A. Control Plan
ii
1.0 INTRODUCTION
1.1
PRODUCT HISTORY
IRC’s CHP family of surface mount resistors provides
unsurpassed power density.
From the 1206
¼-watt product (CHP1/8) to the current development of a 2010 1-watt offering (CHP1X), global CHP
customers capitalize on the inherent advantages of the CHP’s proprietary materials system and
construction.
The CHP surface mount resistor is a member of IRC’s precision Metal Glaze
TM
resistor product
family that has supplied billions of high-quality electronic components to the automotive, military,
computer, instrumentation, telecommunications, and industrial electronics markets for over 35 years.
IRC’s proprietary Metal Glaze
TM
technology provides an inherent and unsurpassed combination of
TM
ruggedness, performance and low cost. The reliability of the Metal Glaze family is supported by
well
over 1 billion unit hours of life testing with no failures.
The CHP uses the same resistive element as its established-reliability, military-qualified leaded
counterpart. IRC has supplied demanding customers with tens of millions of CHP resistors since
introducing the product in 1980, and has experienced
no field failures.
The CHP series, as all of
the Metal Glaze
TM
family, is manufactured in the United States at IRC’s Boone, North Carolina
facility, a QS-9000 registered facility.
1.2
PRODUCT DESCRIPTION
The CHP is a monolithic precision surface mount resistor with cylindrical geometry. The basis of the
component is a Metal Glaze
TM
resistive element, with a capless solder termination. The component
is available in several package sizes, allowing power rating between 1/8 and 2 Watts.
This unique construction not only provides a cost effective solution to common applications where
reliability is a major concern, but also offers some unique features to surface mount technology.
Some important characteristics of the CHP are listed below:
The inherent ruggedness of the Metal Glaze
TM
element can absorb
higher voltage surges and overloads
than its thin film metal
oxide/metal film and thick film flat counterparts. The CHP can withstand
extreme temperatures resulting from to power overloads or circuit ambient
heating.
The CHP family offers
high power density
packages, including a 1/4-
watt 1206 footprint.
The CHP1X, currently under development, is expected to offer
1-watt,
70
°
C performance in a 2010
package.
Compared to surface-mount wirewound products, the CHP is extremely
cost competitive.
IRC’s CHP series is often used by designers as an
1
1.0 INTRODUCTION
alternative to surface-mount wirewound components, allowing IRC
customers to enjoy a
30% - 60% cost savings.
The relatively simple design and construction of the CHP provides
benefits in
long-term reliability.
The product provides solder-dipped
nickel terminals, providing electrical continuity from the solder pad to the
resistive element without the need for end-caps or weld-joints. The Metal
Glaze
TM
technology provides a resistive element that is
impervious to
environmental conditions
without the need for an airtight encapsulation.
The cylindrical high alumina ceramic substrate provides
excellent
thermal conductivity
for maximum heat dissipation and provides
superb
mechanical strength
to withstand the stresses present during board
assembly, mounting, and operation.
The solder termination provides
superb solderability.
Unlike the typical
MELF components that use end-cap termination there is no dog-bone
shape to interfere with pick and place accuracy.
The CHP series offers resistance values as low as 0.050Ω, providing
customers with a cost-efficient,
low-inductance current sense resistor.
The CHP offers a
broad resistance range (0.050
Ω
- 2.2M
Ω
)
in a limited
number of package sizes, simplifying IRC’s customers manufacturing
processes by reducing the number of packages required.
Several special products are available based on this product, including
Zero ohm jumpers
(ZCHP), negative TCR components, and fully-
certified military products with DSCC drawings.
The CHP is offered with
tolerance as low as
±
0.25%
and
TCR as low as
±
50 PPM/
°
C.
These characteristics are provided without the tremendous
cost premiums required of flat thick-film competitors.
IRC is committed to
quick delivery
of the CHP. Non-standard resistance
values are available with a normal lead-time of 4 to 6 weeks. Expedited
delivery for customer demands exceeding the normal lead-time is available.
2
2.0
2.1
PRODUCT MANUFACTURE, STRUCTURE, AND QUALITY CONTROL
MANUFACTURE AND STRUCTURE
2.1.1
FIRING
TM
The Metal Glaze process starts with a high-grade alumina rod. After a metal-to-glass ratio
has been determined (to achieve desired resistance value), milled glaze is applied by dipping
the rod and withdrawing it at a controlled rate for uniform film-thickness control
The dipped rods are then fired at approximately 1000°C. As the glass in the glaze melts and
flows during firing, It creates a form of microencapsulation of the metal particles in this
process, the glass also forms a strong bond with the vitreous phase in the alumina substrate
2.1.2
TERMINATING
After firing, the glazed rods are masked in preparation for diamond sawing to the desired
length and in preparation for several stages of chemical processing.
Following the application of a selectively plated electroless nickel termination and other
treatments, the elements are robotically solder dipped. The standard termination for the CHP
is 60% Sn / 40% Pb solder.
2.1.3
BINNING
The elements in a firing batch are automatically sorted into lots with narrow resistance bands
(“bins”). Resistors are manufactured from a sample of the batch and evaluated using a
standard series of tests before acceptance of the batch. These tests cover mechanical
characteristics, DC resistance, TCR, solderability and STOL. Accepted elements are then
stored until needed. This lot acceptance testing allows IRC continuous monitoring of its
manufacturing system.
2.1.4
ADJUSTING TO FINAL RESISTANCE VALUE
When an order is placed, IRC’s production staff select an appropriate “bin” to meet the
customer’s required resistance and TCR. The resistance value is determined by using a
laser to cut a helical path, increasing resistance, while a precision resistance bridge monitors
resistance. When the resistance value is reached, the equipment controller shuts off the
laser and verifies that the helical conductor path covers an acceptable fraction of the element
length. IRC accepts only those elements that meet resistance and helixing requirements.
2.1.5
APPLYING THE DIELECTRIC COATING
A dielectric coating is applied to the resistor to seal the surface of the component from debris
that could affect performance and provide a dielectric layer to the customer.
3
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