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A Testing
Time for PCB's
Thorough
and consistent production testing is absolutely
vital for fire protection products which are
in continuous use and often have an expected
service life in excess of 10 years.
For
many years, Kentec Electronics Limited has used
Automatic Test Equipment (ATE) for functionally
testing our products. This started with a single,
dedicated machine for testing active end of
line units. We are currently using a number
of National Instruments based systems for testing
a wide range of products.
Test Department
To
maximise its effectiveness and hedge against
equipment failures our ATE system is split in
to 2 parts;
1.
An interchangeable cassette and receiver for
mechanical connections and any additional interface
electronics to which the unit under test is
fixed.
2. A National Instruments PXI chassis which
contains the processing unit, analogue measuring
equipment and digital input output (I/O) lines.
Interchangeable
Cassette/Receiver
The
interchangeable cassette and receiver system
provides a flexible testing set-up as any cassette
can be used on any receiver, so that only the
cassette itself is dedicated to one product.
On
to the cassette additional interface hardware
is often added to provide isolation between
the National Instruments PXI chassis and the
unit under test (UUT) or to provide quiescent
or test conditions based on the product specification/data
sheet.
Below
is a picture of a cassette during construction.
The National Instruments PXI chassis
The
National Instruments PXI chassis provides accurate
measurement, up to 6 1/2 digits, of voltage,
current, or resistance.
This
allows the analogue voltages found on zones,
sounders and Aux outputs to be measured and
verified within design limits at any point during
the testing.
The
National Instruments PXI chassis also has digital
I/O lines that are used to simulate the various
test conditions such as a Fire, short circuit,
open circuit etc on the appropriate zones and
sounder outputs.
The
digital I/O lines are also used to monitor the
status of the UUT outputs such as Fire, Fault,
Alarm etc to ensure that they are ALL in the
correct state for the particular test.
How Do We Use The Test Results?
Kentec
ATE produces raw data that allows us to monitor
First Time Pass rate (FTP) and the point at
which a UUT failed. Analysis of this data allows
continuous process, operator and design improvements
to be carried out.
Each
PCB carries a unique serial number based on
its batch number, in the form of a bar code.
The barcode is scanned in to the ATE at the
beginning of the test along with the part number
and this information and the result of the test
is saved to a central server.
Any
repair details on failed units are also stored
on the central server enabling the cross referencing
of PCB number, sequence failure number and repair
carried out to be analyzed.
Future ATE Projects
Kentec
are committed to the use of automatic test equipment
to ensure quality and high production yield
and future ATE projects include;
1.
Concurrently engineering new products with ATE
in mind at the design stage.
2. Investigating vision systems to detect failures
before the testing stage.
3. Implementing an ‘Expert System’
based on the information gathered.
ATE is part of the continuing investment in
production technology, new products and improvements
to customer service which will enable Kentec
to maintain its position as the UK’s leading
manufacturer of fire alarm control equipment.
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