Innovative fixture system for onboard program- ming of flash devices.
Modern loaded board testing faces tough challenges, including the ongoing trend towards miniaturisation and increasing packing densities on PCBs and hybrid circuits. The probing of components and entire assemblies is now subject to far stricter requirements. To achieve sophisticated testing in terms of both quality and quantity, accurate and reproducible probing of a far greater number of nets is required, on structures that can sometimes be tiny. - This trend has been emerging for several years now.
Leitec GmbH in Holzgerlingen set out to tackle the market requirements and design an fixture system for fine pitch structures.
With the available technology, test pads with a diameter of up to 0.3 mm for a grid array of 0.5 mm can now be securely probed. Contact forces of between 0.8N and 4N may be selected. This means that the same contact pressure can be applied to all test points on an adaption, irrespective of the density or its size.
As a result, most layout and final testing requirements can be successfully coordinated and satisfied.
Implementing this method greatly enhances the efficiency of InCircuit testing as the space required for test pads in the layout is reduced by a factor of 4. Despite this significant reduction in the space required, it is not always possible to position all necessary test pads correctly in the layout. This problem has been overcome by direct bonding of the components.
What does this mean in practice?
The remaining component pad of a flash device is bonded with a pitch of 0.5 mm and pad size of 0.3 mm x 0.5 mm. In-circuit testing and programming of the device can thus be carried out directly.
As a general rule: The FinePitch fixture system from Leitec GmbH Holzgerlingen may be used for all vacuum fixtures, mechanical fixtures or InLine systems. Furthermore, we guarantee that our test probes will long outlast those used in standard fixtures.
Our fixture system for electrical testing of loaded boards are designed to cope with future requirements while helping to minimise today's testing problems.
Source: EPP Elektronik Produktion & Prüftechnik,
March/April 2005 edition.