Revolutionary Fine Pitch Test Fixturing System for Incircuit- /Functional Test at 0.5mm pitch.
uwe electronic, one of the leading suppliers in the ATE field, has developed a completely new fixture system, called ZOOM-FIXTURING. This revolutionary system is designed to test any kind of Printed Circuit Boards (PCB) or hybrids with very small test pads and pitches down to 0.3mm.
General Challenge:
It is well-known fact that the miniaturization of PCBs and hybrids is continuously proceeding. Together with this development the density of components is also increasing. Therefore, the test structures are getting smaller which consequently leads to smaller test pads and smaller pitches. Today’s specifications for structures on PCBs usually show pitches of 2.54mm (100mil) down to 1.27mm (50mil) with pad diameters lager than 0.8mm (31mil). So we often run into the problem that we can’t place the required number of test pads witch in the end reduces the test coverage significantly. The following chart gives you an overview of how the complexity of PCBs has changed during the last decades.
| 1970 | 1980 | 1990 | 2000 | |
|---|---|---|---|---|
| no. of layers | 4 | 10 | 20 | > 40 |
| no. of drill holes/cm² | 6 | 16 | 64 | > 150 |
| height [mm] | 1,5 | 3,0 | 5,0 | 10,0 |
| mounting hole size [mm] | 1,0 | 0,6 | 0,3 | 0,1 |
| trace width [mm] | 0,25 | 0,13 | 0,08 | 0,03 |
| dimensions [mm] | 254x381 | 495x600 | 600x600 | 1200x600 |
Approach:
The above mentioned general technical challenge motivated us to develop a completely new and revolutionary test fixture system: the ZOOM-FIXTURING.
Targets:
- Our solution has to fit to Standard Vacuum, Mechanical and Pneumatic Fixtures as well as to In-Line Systems.
- We have to realize a pitch of 0.5mm (20mil) or better at standard tolerances of PCBs.
- We need to get a reliable contact on pads with a diameter of 0.3mm (12mil) at standard tolerances of PCBs.
- We must be able to contact both sides of the PCB.
- There must be a way to change the pins fast and easily.
- The costs for spare parts need to be kept at a low level.
- When re-designing a PCB or similar devices we have to guarantee that the customer wouldn’t need a completely new fixture. So our ZOOM-FIXTURING system will also be interesting for pre-serial tests.