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.

Kentec Electronics Ltd.
Tel: +44 (0)1322 222121 Fax: +44(0)1322 291794