Design for Reliability
Design for Reliability is woven throughout our multi-phased, new-product-
development process. Design-for-reliability practices are fully documented
and begin early in the new-product development cycle with the following
goals:
1. To work from an approved components/vendors list ensuring the use of
reliable components and the rigorous qualifi cation of new components.
2. To design with safety margins by adhering to a strict set of derating
guidelines and performing theoretical worst-case analyses.
3. To locate potential design weaknesses early in the product-development
cycle by using extensive HALT (Highly Accelerated Life Testing).
4. To prove that early design improvements are effective by employing a
thorough FRACA (Failure Reporting Analysis and Corrective Action)
system.
HALT Testing
The goal of the accelerated-stress techniques used by Murata Power
Solutions is to force device maturity, in a short period of time, by exposing
devices to excessive levels of "every stimulus of potential value." We use
HALT (Highly Accelerated Life Testing) repeatedly during the design and
early manufacturing phases to detect potential electrical and mechanical
design weaknesses that could result in possible future fi eld failures.
During HALT, prototype and pre-production DC/DC converters are sub-
jected to progressively higher stress levels induced by thermal cycling,
rate of temperature change, vibration, power cycling, product-specifi c
stresses (such as dc voltage variation) and combined environments. The
stresses are not meant to simulate fi eld environments but to expose any
weaknesses in a product’s electro/mechanical design and/or assembly
processes. The goal of HALT is to make products fail so that device weak-
nesses can be analyzed and strengthened as appropriate. Applied stresses
are continually stepped up until products eventually fail. After corrective
actions and/or design changes, stresses are stepped up again and the cycle
is repeated until the "fundamental limit of the technology" is determined.
Murata Power Solutions has invested in a Qualmark OVS-1 HALT tester
capable of applying voltage and temperature extremes as well as 6-axis,
linear and rotational, random vibration. A typical HALT profi le (shown above)
consists of thermal cycling (–55 to +125°C, 30°C/minute) and simultane-
ous, gradually increasing, random longitudinal and rotational vibration up
to 20G’s with load cycling and applied-voltage extremes added as desired.
Many devices in Murata Power Solutions' new A-Series could not be made
to fail prior to reaching either the limits of the HALT chamber or some pre-
viously known physical limit of the device. We also use the HALT chamber
and its ability to rapidly cool devices to verify their "cold-start" capabilities.
Qualifi cation
For each new product, electrical performance is verifi ed via a comprehensive
characterization process and long-term reliability is confi rmed via a rigorous
qualifi cation procedure. The qual procedure includes such strenuous tests as
thermal shock and 500 hour life. Qual testing is summarized below.
In-Line Process Controls and Screening
A combination of statistical sampling and 100% inspection techniques
keeps our assembly line under constant control. Parameters such as
solder-paste thickness, component placement, cleanliness, etc. are statisti-
cally sampled, charted and fi ne tuned as necessary. Visual inspections are
performed by trained operators after pick-and-place, soldering and cleaning
operations. Units are 100% electrically tested prior to potting. All devices
are temperature cycled, burned-in, hi-pot tested and fi nal-electrical tested
prior to external visual examination, packing and shipping.
Rapid Response to Problems
Murata Power Solutions employs an outstanding corrective-action system
to immediately address any detected shortcomings in either products or
processes. Whenever our assembly, quality or engineering personnel spot
a product/process problem, or if a product is returned with a potential
defect, we immediately perform a detailed failure analysis and, if necessary,
undertake corrective actions. Over time, this system has helped refi ne our
assembly operation to yield one of the lowest product defect rates in the
industry.
Typical HALT Profi le
Qualifi cation Test Method/Comments
HALT Murata Power Solutions in-house procedure
High Temperature Storage Max. rated temp., 1,000 hours
Thermal Shock 10 cycles, –55 to +125°C
Temperature/Humidity +85°C, 85% humidity, 48 hours
Lead Integrity Murata Power Solutions in-house procedure
Life Test +70°C, 500 hours*
Marking Permanency Murata Power Solutions in-house procedure
End Point Electrical Tests Per product specifi cation
Qualifi cation Testing
* Interim electrical test at 200 hours.
10 20 30 40 50 60 70 80 90
40
20
0
Random Vibration
G's
Temperature (°C)
Test Time (minutes)
100
80
60
40
20
0
–20
–40
www.murata-ps.com/support
Murata Power Solutions, Inc. makes no representation that the use of its products in the circuits described herein, or the use of other
technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained herein do not imply
the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifi cations are subject to change without
notice. © 2015 Murata Power Solutions, Inc.
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfi eld, MA 02048-1151 U.S.A.
ISO 9001 and 14001 REGISTERED
This product is subject to the following operating requirements
and the Life and Safety Critical Application Sales Policy:
Refer to: http://www.murata-ps.com/requirements/
UWR Series
Single Output, High Reliability, 2" x 2", 14-20 Watt, DC/DC Converters
MDC_UWR14-20 Series.G01 Page 6 of 6
