5.2 Description of the Fixture System
5.2.1 Description
The Voltech AT Series fixture system allows you freedom and flexibility when considering your fixturing needs.
All fixtures are mounted on fixture boards, which are available as a blank fixture plate and also as fixture kit which contains parts to help you.
APPLICATION
The fixture is designed to connect to wound components with the following characteristics:
Size:
A footprint of up to 63.5mm square
A height of up to 63.5mm
A connection matrix up to 60mm square
Connection Types:
Surface mount.
Pin connection.
Blade connection.
Flying leads
Pitches of: -
1.27mm
1.962mm(0.156”)
2.00mm
2.5mm
2.54mm (0.1”)
3.81mm (0.15”)
There are some application limitations to the above, for example, the minimum pitch of the blade type that can be connected to is determined by the minimum pitch that the necessary connector can be put on.
Also though a 1.27mm pitch is available it is only anticipated that component connections will be on multiples of this pitch and there will not be two connections only 1.27mm apart.
COMPATIBLE CONNECTION TYPES
Kelvin clips
Kelvin blades (Automech type)
4mm sockets
ATE pin types
Rotary point
Castellated
Point
Cup
Crown
A list of known suitable ATE pin types is available from Voltech.
THE COMPONENTS
1. BASE PLATE
This fits into the top of the transformer tester and has the following features:
- Fitted with 40 node contacts which connect to the 40 test node pins on the top of the tester.
- Moulded indents on the bottom surface to act as drill guide marks for ease of drilling to fit:
4mm safety sockets as a universal or for specific applications. Termination posts
- Provision for drilling through and fitting inserts for the attachment of a clamp in either the left or right hand position.
- Slots moulded into the base to support wiring to the connection points from the nodes.
- Four mounting pillars to hold the cover plate (supplied). The cover plate fits on to the underside of the fixture by four snap rivets to protect the wiring from accidental damage. It locates into moulded sockets in the Fixture Board by a simple press-fit action.
The fixture parts are made using a high-pressure injection moulding process in a material that is suitable for soldering temperatures and the high voltage that will exist during use.
2. INTERFACE PLATE
The interface plate is a glass fibre board with an injected plastic trim and fits into the bezel in close alignment with the Probe Housing box. The interface plate supports the body of the test piece during testing.
The bezel has 4 groups of 2 x M3 inserts for the attachment of the guides. The plate can accommodate a test piece of up to 63.5mm square, and can be drilled for probes over an area of 60mm square when using the drilling plates.
3. PROBE HOUSING BOX
The housing box fits into the bezel and base plate. This box has a base thickness of 9mm so that it can be drilled to accommodate a range of ATE probes and Kelvin pins. The housing box is fastened into position by 4*M3 screws which also lock the Bezel into place.
4. BEZEL
This provides an accurate location for the probe housing box and the test piece interface plate. The design also includes support areas for the rear of the guides.
5. GUIDES
The guides help to locate the test piece into the fixture quickly and accurately. They are adjustable to suit the test piece plan size and can be stacked or reversed if required.
The guides are capable of having sections cut off to enable them to be used down to small footprints. Four pairs are shown in the sketch.
6. CLAMP
A clamping mechanism may be purchased to hold the test piece in place for testing.
The clamp head has a sliding guide which allows the vertical clamping rod to move horizontally relative to the clamp head. This minimises the possibility of side movement to the test piece during the clamping action.
The clamp head is also designed to accommodate springs of force ratings of 2.9N/mm, 4.5N/mm and 5.4N/mm to allow for the differing types of probes used for wound component connections.
7. HEIGHT BLOCKS
Height adjustment blocks are capable of being stacked in order to clamp a UUT of up to 70mm in height in 10mm steps.
8. TOOLING
To enable the probe housing box and the test piece interface plate be drilled to the accuracy required, drilling templates are available in the following grid pitches:
1.27mm
2.00mm
2.50mm
2.54mm
3.81mm
To hold the drilling templates in place for drilling, clips are provided to hold the drilling templates in place. They clip into holes provided at the corners of the interface plate and the probe housing box.
You can also make use of the free area behind the fixture, allowing you to mount other clamps, handling accessories, ink jet spray printers or even a scanning bar code reader close to the point of test.
ASSEMBLY AND WIRING
A comprehensive guide to the construction of your own custom fixtures is supplied with each custom fixture plate kit (see section 2.2 of this chapter).