Messsonde

Abstract

Measuring probe (1) for capacitive detection of connection faults of soldered components on a circuit board, comprising a probe plate (2) with a plate plane (E) and an elongated connecting element (3) having a longitudinal axis (L) which can be detachably attached to the probe plate (2) for the detachable connection of a single-pole electrical conductor (4) to the probe plate (2), wherein the connecting element (3) can be attached to the probe plate (2) with its longitudinal axis (L) perpendicular to the plate plane (E), and wherein anti-rotation elements (5;6) are arranged both on the probe plate (2) and on the connecting element (3) which prevent the connecting element (3) from rotating about its longitudinal axis (L) in relation to the probe plate (2) when the connecting element (3) is attached to the probe plate (2).

Description

[0001] The present invention generally relates to technology for detecting connection defects, such as soldering defects and open connections, on or beneath integrated circuits on circuit boards. Specifically, the present invention relates to a measurement probe for capacitively detecting connection defects of soldered components on a circuit board.

[0002] There are various, sometimes complementary, techniques for testing components and electrical connections between components on printed circuit boards or circuit boards. For example, the components and electrical connections on the circuit boards can be contacted using spring-loaded or non-spring-loaded test contact pins, and an electrical connection can be established to an external test system. Electrical signals are transmitted from the test system to the contact points and back to detect faults. There are also capacitive systems in which a probe plate of a measuring probe is placed on an integrated circuit or component. A 1 kHz signal, for example, is then fed into each of the individual pins of the integrated circuit or component, while the other pins are grounded.The resulting signal is capacitively measured at the probe plate, amplified and evaluated to detect connection errors.

[0003] The present invention relates to this second (capacitive) technology. The probe plate must be tailored (if necessary individually) to the corresponding size of the component to be measured, whereby even very small components down to approximately 2 x 4 mm must be tested. The measuring probes expediently consist of a probe plate and a connecting element (also called an adapter). These two elements are constructed separately and can be mechanically and electrically connected to one another. This enables the probe plate to be placed stably and precisely on the component to be tested. The connecting element is then mechanically and electrically fastened to the probe plate. This results in simple and quick interchangeability of both elements, which is particularly advantageous given the often tight space, especially in 24-hour shift operations and maintenance by unskilled personnel.A problem with conventional measuring probes is that the electronic measuring amplifier is mounted in close proximity to the probe plate to amplify the weak measurement signal from the probe plate and transmit it to the evaluation electronics. This is mechanically vulnerable and impedes easy maintenance and replacement in the event of problems.

[0004] The disadvantages of the known measuring probes are solved according to the invention by a measuring probe for the capacitive detection of connection faults of soldered components on a circuit board according to independent claim 1. Further advantageous embodiments are defined in the dependent claims.

[0005] The measuring probe according to the invention comprises a probe plate with a plate plane and an elongated connecting element, which can be releasably fastened to the probe plate and has a longitudinal axis, for releasably connecting a single-pole electrical line to the probe plate. The connecting element can be fastened to the probe plate with its longitudinal axis perpendicular to the plate plane. Anti-rotation elements are arranged on both the probe plate and the connecting element, which prevent the connecting element from rotating about its longitudinal axis relative to the probe plate when the connecting element is fastened to the probe plate.

[0006] The inventive design of the measuring probe enables reliable and easy replacement of the connecting element in the event of a malfunction or defect. The use of a single-pole electrical cable has the advantage that the measuring probe according to the invention is electrically insensitive to accidental mechanical rotation of the connecting element about its longitudinal axis relative to the probe plate. Furthermore, the anti-rotation elements according to the invention prevent mechanical rotation of the connecting element relative to the probe plate, thus guaranteeing reliable positioning of the measuring probe on the soldered components of a circuit board to be tested.The inventive design of the measuring probe thus enables the connecting element to be replaced even by untrained personnel and ensures that the measuring probe is used in a correctly defined electrically and mechanically position. Furthermore, the inventive design enables the signal line in the connecting element, and thus also the signal path to the measuring amplifier, to be shielded as effectively as possible. Furthermore, the inventive design enables the probe plate to be held stably, mounted in a torsion-proof manner, and possibly even mounted with a slight spring, which is supported by the inventive design of the probe plate and connecting element.

[0007] Advantageously, the connecting element comprises an elongated sleeve in which the single-pole electrical cable is arranged. At one end, the sleeve has an anti-rotation element that interacts with an anti-rotation element of the probe plate. The elongated sleeve thus serves to accommodate and secure the single-pole electrical cable. Furthermore, the elongated sleeve can be accommodated in another sleeve, for example, a spring-loaded sleeve or the like, to enable spring-loaded mounting of the measuring probe on the components to be tested.

[0008] Advantageously, the anti-rotation elements of the probe plate and the connecting element are also designed to secure the connecting element and the probe plate. In other words, the anti-rotation elements of the probe plate and the connecting element are designed to both secure the connecting element against rotation with respect to the probe plate and to secure the connecting element to the probe plate. Alternatively, designs are conceivable in which these two functions are provided by separate elements.

[0009] Advantageously, the anti-rotation element of the connecting element has two parallel straight elements, between which an end of the single-pole electrical cable to be connected to the probe plate is exposed. This enables a simple electrical connection of the single-pole electrical cable to a corresponding electrical connection of the probe plate. The two parallel straight elements of the anti-rotation element of the connecting element provide the anti-rotation protection of the connecting element with respect to the probe plate. These two parallel straight elements of the anti-rotation element of the connecting element advantageously interact with two corresponding elements of the anti-rotation element of the probe plate arranged on the probe plate, which elements are shaped to prevent the connecting element from twisting relative to the probe plate.Here, the two parallel straight elements of the anti-rotation element of the connecting element are designed as parallel ribs that can be clamped to the elements of the anti-rotation element of the probe plate arranged on the probe plate. As a result, the cooperating parallel straight elements of the connecting element and the probe plate simultaneously provide the anti-rotation function and the fastening function. Advantageously, the two parallel ribs are part of a substantially square rotating part arranged on the elongated connecting element. Advantageously, the elements of the anti-rotation element of the probe plate arranged on the probe plate are formed by webs fastened to the probe plate, on the outer sides of which the two parallel straight elements of the anti-rotation element of the connecting element clamp.The webs attached to the probe plate are advantageously part of a rectangular structure. The rectangular structure can be square and have an opening in which connecting elements are arranged for electrically connecting the probe plate to the single-pole electrical line of the elongated connecting element.

[0010] Advantageously, the single-pole electrical cable of the elongated connecting element has a shield. The shield of the single-pole electrical cable can advantageously extend over the entire length of the elongated connecting element.

[0011] Advantageously, the single-pole electrical line of the elongated connecting element is a coaxial cable fastened in the elongated connecting element.

[0012] The following invention will be explained in more detail below using a preferred embodiment with reference to the attached figures. Fig. 1 a schematic side view of a measuring probe according to the invention, Fig. 2 a sectional view of the Fig. 1 shown measuring probe, Fig. 3 a schematic perspective view of the Fig. 1 and Fig. 2 shown measuring probe, Fig. 4 a sectional view of the connecting element and the single-pole electrical cable of the measuring probe of the Fig. 1, Fig. 2 and Fig. 3, Fig. 5 a schematic side view of the connecting element and the single-pole electrical cable of Fig. 4, Fig. 6 a schematic perspective view of the connecting element and the single-pole electrical line of the Fig. 4 and Fig. 5, Fig. 7 a schematic side view of the probe plate of the measuring probe of the Fig. 1, Fig. 2 and Fig. 3, Fig. 8 a schematic plan view of the probe plate of Fig. 7, and Fig. 9 a schematic perspective view of the probe plate of the Fig. 7 and Fig. 8.

[0013] The attached Fig. 1 to 9 show a measuring probe 1 according to the invention and its components in various views. As already explained in the introduction to this description, the measuring probe according to the invention serves for the capacitive detection of connection faults in soldered components on a circuit board. The areas of use and applications of measuring probes of this type have already been explained in the introduction to this description, and the measuring probe 1 according to the invention can also be used in the same way.

[0014] The measuring probe 1 according to the invention comprises a probe plate 2 with a plate plane E and an elongated connecting element 3 which can be releasably fastened to the probe plate 2 and has a longitudinal axis L for releasably connecting a single-pole electrical line 4 to the probe plate 2. The schematic side view of the Fig. 1, the sectional view of the Fig. 2 and the perspective view of the Fig. 3 shows the connecting element 3 and the probe plate 2 in the connected state.

[0015] The connecting element 3 with the single-pole electrical cable 4 fastened therein is shown again in a sectional view in Fig. 4, a schematic side view in Fig. 5 and a perspective view in Fig. 6. The probe plate 2 is shown in a schematic side view in Fig. 7, in a plan view in Fig. 8 and in a perspective view in Fig. 9 shown.

[0016] The elongated connecting element 3 has a significantly greater length than width or diameter and thus defines a longitudinal axis L, which is in the Fig. 1 and Fig. 5. In the illustrated embodiment, the connecting element 3 comprises an elongated sleeve 7 in which the single-pole electrical cable 4 is arranged and secured. The elongated sleeve 7 has a round diameter, so that the longitudinal axis L forms the central axis of this sleeve 7 and thus of the connecting element 3.

[0017] The probe plate 2 is flat, meaning it has an essentially two-dimensional shape with a width and length that are each significantly greater than its height. In the example shown, the probe plate 2 is square, but it can also be rectangular with any desired dimensions. The flat shape of the probe plate 2 defines a plate plane E, which is Fig. 1 and Fig. 7. In the top view of the probe plate 2 of the Fig. 8 the plate plane E corresponds to the drawing plane.

[0018] When the connecting element 3 and the probe plate 2 are connected, the longitudinal axis L of the connecting element 3 is perpendicular to the plate plane E. This also implies that this perpendicular relationship may contain a deviation of a few degrees, for example, due to measurement or construction tolerances. Furthermore, it should be emphasized that the longitudinal axis L refers exclusively to the sleeve 7, which has a rigid shape. Although the Fig. 1 and Fig. 5 also shows the longitudinal axis L as the longitudinal axis of the single-pole electrical cable 4, this single-pole electrical cable 4 can also be designed to be flexible, for example, as a conventional coaxial cable. In this case, the cable 4 does not have a defined longitudinal axis L, except in the straight state.

[0019] In the Fig. 7, Fig. 8 and Fig. 9 it can be seen that the probe plate 2 has a rotation-locking element 5 approximately centrally on its upper side, to which an electrical connection 8 is attached. The rotation-locking element 5 has a square base with two opposing parallel straight webs 5a and 5b, which interact with corresponding elements of the connecting element 3. These elements of the connecting element 3 are parallel and opposing ribs 6a and 6b at the lower end of the connecting element 3, as shown, for example, in the Fig. 4, Fig. 5 and Fig. 6 can be clearly seen. The two ribs 6a and 6b are designed in such a way that they accommodate the two webs 5a and 5b between them and can thus clamp and fasten the connecting element 3 to the probe plate 2 in a non-rotatable manner. In the example shown, the two ribs 6a and 6b are formed on a square rotating element 6 which is arranged at the lower end of the connecting element 3. Since the two parallel webs 5a and 5b are also arranged on a square anti-rotation element 5 of the probe plate 2, the round shape of the single-pole electrical line 4 results in four positions offset by 90 degrees from one another, with which the connecting element 3 can be fastened to the probe plate 2. Since the electrical line 4 is single-pole, these four positions are all electrically equivalent.However, by appropriately designing the anti-rotation elements 5 and 6 in a rectangular shape, it is also possible to provide configurations in which only two positions of the connecting element 3 offset by 180 degrees relative to each other are provided with respect to the probe plate 2.

[0020] The electrical connection 8 of the probe plate 2 is round and cooperates with a corresponding round end 9 of the electrical line 4 at the lower end of the connecting element 3. If the single-pole electrical line 4 is designed as a coaxial cable, the two electrical connections 8 and 9 are designed as conventional coaxial connection connections. However, other designs of a single-pole electrical line with continuous shielding can also be used.

[0021] Furthermore, in the Fig.1 to 6 clearly show that the elongated sleeve 7 of the connecting element 3 is surrounded on the outside by another, shorter sleeve 10, which slides on the elongated sleeve 3 and is resiliently mounted by means of a spring arranged at the lower end of the sleeve 3 facing the anti-rotation elements. The rotation of the shorter sleeve 10 with respect to the elongated sleeve 3 is prevented by a pin 11 attached to this lower end of the sleeve 3, which engages in a corresponding slot in the shorter sleeve 10. The resilient mounting of the shorter sleeve 10 on the elongated sleeve 3 enables resilient mounting of the measuring probe on the components to be tested.

Claims

[1] Measuring probe (1) for the capacitive detection of connection faults of soldered components on a circuit board, comprising a probe plate (2) with a plate plane (E) and an elongated connecting element (3) which can be releasably fastened to the probe plate (2) and has a longitudinal axis (L) for releasably connecting a single-pole electrical line (4) to the probe plate (2), wherein the connecting element (3) can be fastened with its longitudinal axis (L) perpendicular to the plate plane (E) on the probe plate (2), and wherein anti-rotation elements (5; 6) are arranged both on the probe plate (2) and on the connecting element (3), which prevent rotation of the connecting element (3) about its longitudinal axis (L) with respect to the probe plate (2) when the connecting element (3) is fastened to the probe plate (2). [2] Measuring probe (1) according to claim 1, wherein the connecting element (3) comprises an elongated sleeve (7) in which the single-pole electrical line (4) is arranged, and which has at one end a rotation-locking element (6) which cooperates with a rotation-locking element (5) of the probe plate (2). [3] Measuring probe (1) according to claim 1 or 2, wherein the anti-rotation elements (5; 6) of the probe plate (2) and the connecting element (3) are also designed to fasten the connecting element to the probe plate (2). [4] Measuring probe (1) according to claim 1, 2 or 3, wherein the anti-rotation element (5) of the connecting element (2) has two parallel straight elements (5a, 5b), between which an end of the single-pole single-pole electrical line (4) to be connected to the probe plate (2) is exposed. [5] Measuring probe (1) according to claim 4, wherein the two parallel straight elements (6a, 6b) of the anti-rotation element (6) of the connecting element (3) interact with two corresponding elements (5a, 5b) of the anti-rotation element (6) of the probe plate (2) arranged on the probe plate (2) in such a way that rotation of the connecting element (3) with respect to the probe plate (2) is prevented. [6] Measuring probe (1) according to claim 5, wherein the two parallel straight elements (6a, 6b) of the anti-rotation element of the connecting element (3) are designed as parallel ribs which can be clamped to the elements (5a, 5b) of the anti-rotation element (5) of the probe plate (2) arranged on the probe plate (2). [7] Measuring probe (1) according to claim 6, wherein the two parallel ribs are part of a substantially square rotary part arranged on the elongated connecting element (3). [8] Measuring probe (1) according to claim 6 or 7, wherein the elements (5a, 5b) of the anti-rotation element (5) of the probe plate (2) arranged on the probe plate (2) are formed by webs fastened to the probe plate (2), on the outer sides of which the two parallel straight elements (6a, 6b) of the anti-rotation element (6) of the connecting element (3) are clamped. [9] Measuring probe (1) according to claim 8, wherein the webs attached to the probe plate (2) are part of a rectangular structure. [10] Measuring probe (1) according to claim 9, wherein the rectangular structure is square and has an opening in which connecting elements for electrically connecting the probe plate (2) to the single-pole electrical line (4) of the elongated connecting element (3) are arranged. [11] Measuring probe (1) according to one of the preceding claims, wherein the single-pole electrical line (4) of the elongated connecting element has a shield. [12] Measuring probe (1) according to claim 11, wherein the shielding of the single-pole electrical cable (4) extends over the entire length of the elongated connecting element (3). [13] Measuring probe (1) according to one of the preceding claims, wherein the single-pole electrical line (4) of the elongated connecting element (3) is a coaxial cable fastened in the elongated connecting element (3).

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