Quality and Reliability

The A-Series are the first DC/DC Converters to emerge from MPS’s new,

company-wide approach to designing and manufacturing the most reliable

power converters available. The five-pronged program draws our Quality

Assurance function into all aspects of new-product design, development,

characterization, qualification and manufacturing.

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 qualification 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 MPS 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 Acceler-

ated Life Testing) repeatedly during the design and early manufacturing

phases to detect potential electrical and mechanical design weaknesses

that could result in possible future field 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-specific

stresses (such as dc voltage variation) and combined environments. The

stresses are not meant to simulate field environments but to expose any

weaknesses in a product’s electro/mechanical design and/or assem-

bly processes. The goal of HALT is to make products fail so that device

weaknesses 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.

MPS has invested in a Qualmark OVS-1 HALT tester capable of applying

voltage and temperature extremes as well as 6-axis, linear and rota-

tional, random vibration. A typical HALT profile (shown above) consists of

thermal cycling (–55 to +125°C, 30°C/minute) and simultaneous, gradually

increasing, random longitudinal and rotational vibration up to 20G’s with

load cycling and applied-voltage extremes added as desired. Many devices

in MPS’s new A-Series could not be made to fail prior to reaching either

the limits of the HALT chamber or some previously 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.

Qualification

For each new product, electrical performance is verified via a comprehen-

sive characterization process and long-term reliability is confirmed via a

rigorous qualification procedure. The qual procedure includes such strenu-

ous 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 statistically sampled,

charted and fine 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 tem-

perature cycled, burned-in, hi-pot tested and final-electrical tested prior to

external visual examination, packing and shipping.

Rapid Response to Problems

MPS employs an outstanding corrective-action system to immediately

address any detected shortcomings in either products or processes. When-

ever 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 refine our assembly operation to

yield one of the lowest product defect rates in the industry.

Typical HALT Profile

Qualification Test

Method/Comments

HALT

MPS 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

MPS in-house procedure

Life Test

+70°C, 500 hours*

Marking Permanency

MPS in-house procedure

End Point Electrical Tests

Per product specification

Qualification Testing

* Interim electrical test at 200 hours.

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BWR Models

7-10W, Dual Output DC/DC converters

MDC_BWR-7-10_D01 Page 5 of 5

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the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifications are subject to change without

notice.

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Murata Power Solutions, Inc.

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