HALT Testing

The goal of the accelerated-stress techniques used by DATEL 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 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.

DATEL 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 profile (shown above) consists of thermal

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

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

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

DATEL’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 statisti-

cally 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 temperature cycled, burned-in, hi-pot tested and final-electrical tested

prior to external visual examination, packing and shipping.

Rapid Response to Problems

DATEL 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

DATEL 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

DATEL in-house procedure

Life Test

+70°C, 500 hours*

Marking Permanency

DATEL in-house procedure

End Point Electrical Tests

Per product specification

Qualification Testing

* Interim electrical test at 200 hours.

10

20

30

40

50

60

70

80

90

40

20

0

Test Time (minutes)

100

80

60

40

20

0

–20

–40

UWR Series

Single Output, High Reliability, 2" x 1", 6-10 Watt, DC-DC Converters

MDC_UWR6-10W Series.D02 Page 6 of 6

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notice.

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Murata Power Solutions, Inc.

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