Flying Probe Tester for Substrates down to 10 µm

30 March 2015 - atg Luther & Maelzer introduced a flying probe system for substrate test. The first system was deliverd to a major customer in Korea. The S3 10µm Substrate Tester is the first system of a new atg Luther & Maelzer product line. It meets the challenging requirements of high end substrate test such as positioning accuracy and high number of contact points by applying the advanced flying probe technology of atg Luther & Maelzer.

Substrates are used to enable a connection between a semiconductor and a printed circuit board. A characteristic test panels consists of about 50 - 100 single substrates and has a size of approx. 250 mm x 80 mm. For electrical testing it is necessary to contact all end points of the product. Each substrate has about 1000 – 2000 test points. So on one product about 100,000 pads need to be contacted. For testing substrates on the semiconductor side, structures down to 10 µm have to be reliably contacted.

To meet this challenge the S3 deploys four freely moveable test heads and achieves a test rate of 100 measurements per second. The test heads contact the test product from above and execute a capacitance measurement against a vacuum table. The capacitance result indicates opens and shorts in the substrates.

Prior to electrical test, an optical alignment of the test sample correlates the shrinkage and offset of the finished product with the testing data and adjusts automatically. A 5 Megapixel color camera with a resolution of 1.2 µm ensures positioning accuracy of +/- 1.5 µm.

The S3 works with a micro needle. The contacting pressure of this micro needle can be adjusted from 0.3 g up to 2.5 g to ensure best test yield and repeatability without damaging the contact pads. The maximum test area of the substrate tester S3 is 310 mm x 300 mm (12.2” x 11.8”).

Jochen Kleinertz, vice president PCB Test Group at Xcerra explains: “Today’s established systems work with two test heads and achieve test rates of around 30 measurements per second. With its four test heads architecture the S3 achieves more than three times this speed. We expect that this high throughput capability will enable testing of higher quantities of substrate boards with flying probe test systems in the future. This will provide the customer with an economical test solution for high end substrate boards.

After the successful market introduction of the single-sided S3 we plan to complete our new product line with a double-sided system with eight test heads.”

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