Test needle, test probe, and flying probe tester for testing printed circuit boards
AssigneeAtg Mycronic GmbH
InventorsStefan Weiss, Oleh Yuschuk, Christian Weindel
Life of this patent
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Abstract
The invention relates to a test needle for measuring electrically conductive layers in holes of printed circuit boards, as well as to a test probe equipped with such a test needle and to a flying probe tester for testing printed circuit boards equipped with such a test needle or such a test probe. The test needle has a capacitive measuring body, which is connected via a cable to a capacitive measuring device. The cable is shielded so that only the capacitive measuring body can form a capacitive coupling with other electrically conductive bodies. This makes it possible to determine this capacitive coupling with a high local resolution.
Claims25
A method for measuring electrically conductive layers in holes of bare printed circuit boards, wherein a flying probe tester is used, having at least one test finger, which is able to move freely in a predetermined testing region in order to be able to be moved into the vicinity of a predetermined contact point of the printed circuit board, wherein the test finger has a test needle comprising an electrical conductor, which is enclosed by a shield;
- the test needle has a connecting end, at which it can be electrically connected to a capacitive measuring device, and a measuring end that can be inserted into a hole during a measurement, wherein at the measuring end, a capacitive measuring body that is connected to the electrical conductor is positioned outside of the shield and can form a capacitive coupling with an electrically conductive layer in the hole, wherein a frequency signal generated by a signal generator is applied to at least one conductor track or a plated through-hole of the printed circuit board and at least one further conductor track is connected to electrical ground, wherein the method comprises:
- the test needle with the capacitive measuring body is inserted into a hole, the location of the capacitive measuring body is detected and at the same time, the electrical capacitance of the capacitive measuring body relative to its surroundings is measured so that based on the measured capacitance, a determination is made as to whether an electrical conductor is located in the vicinity of the detected location, wherein the at least one further conductor track that is connected to electrical ground is located in an area on the printed circuit board between (i) the at least one conductor track or the plated through-hole to which the frequency signal is applied and (ii) the capacitive measuring body while the test needle with the capacitive measuring body is inserted into the hole, thereby reducing contributions from parasitic capacitances to conductor tracks other than the at least one conductor track or the plated through-hole.
A test needle for measuring electrically conductive layers in holes of printed circuit boards, comprising:
- an electrical conductor, which is enclosed by a shield, the test needle has a connecting end, at which it can be electrically connected to a capacitive measuring device, and a measuring end that can be inserted into a hole during a measurement;
- wherein at the measuring end, a capacitive measuring body that is connected to the electrical conductor is positioned outside of the shield and can form a capacitive coupling with an electrically conductive layer in the hole;
- and
- wherein the capacitive measuring body is embodied as metallic annular body and an electrically conductive measuring tip is embodied at the measuring end of the test needle.
A method for measuring electrically conductive layers in holes of bare printed circuit boards, wherein a flying probe tester is used, having at least one test finger, which is able to move freely in a predetermined testing region in order to be able to be moved into the vicinity of a predetermined contact point of the printed circuit board, wherein the test finger has a test needle comprising an electrical conductor, which is enclosed by a shield;
- the test needle has a connecting end, at which it can be electrically connected to a capacitive measuring device, and a measuring end that can be inserted into a hole during a measurement, wherein at the measuring end, a capacitive measuring body that is connected to the electrical conductor is positioned outside of the shield and can form a capacitive coupling with an electrically conductive layer in the hole, wherein a frequency signal generated by a signal generator is applied to at least one conductor track or a plated through-hole of the printed circuit board and at least one further conductor track is connected to electrical ground, wherein the method comprises:
- the test needle with the capacitive measuring body is inserted into a hole, the location of the capacitive measuring body is detected and at the same time, the electrical capacitance of the capacitive measuring body relative to its surroundings is measured so that based on the measured capacitance, a determination is made as to whether an electrical conductor is located in the vicinity of the detected location;
- and
- measuring the capacitance between the capacitive measuring body and the plated through-hole while the further conductor track is connected to electrical ground, thereby excluding contributions from parasitic capacitances to other conductor tracks.
Dependencies are inferred from the claim text.