DE102009030540A1 - Electronic component analyzing method involves loading electronic component in mechanical manner, where electronic component is switched in electric circuit, and is applied with electrical signal - Google Patents

Abstract

The electronic component analyzing method involves loading an electronic component (1) in a mechanical manner, where the electronic component is switched in an electric circuit (2). The electronic component is applied with an electrical signal, where an electrical parameter of the electrical circuit is measured. The mechanical load of the electronic component affects the electrical parameter. An independent claim is also included for an electronic component analyzing device.

Description

The The present invention relates to a method and an apparatus for testing electronic components. The present Invention will be with reference to capacitors and in particular ceramic However, it is noted that the present invention also with regard to other electronic Components and in particular other passive electronic components such Resistors, inductors, piezoelectric Components and the like is applicable.

at the production of electronic assemblies are these and in particular also ceramic SMD (Surface Mounted Device) capacitors or electronic components already attached to a circuit carrier such as a printed circuit board, a 3D carrier or the like are largely forced by the manufacturing process mechanically loaded and some of them also damaged by cracking. Often there is no immediate effect of the damage recognizable and noticeable defects may first occur after months on.

The Mechanical stress is usually a bending load, which on the corresponding component unwanted forces exerts.

From the DE 2 404 570 is a pulse current controller for a pulsed Wirbelstromprüfgerät known. This Wirbelstromprüfgerät used for non-destructive testing of electrically conductive objects to determine errors, cracks or bubbles in this. In this case, a Prüfspulenanordnung is energized to induce eddy currents in the object to be tested. However, this method can only be used for certain electronic components and in particular for those components in which eddy currents can be generated or evaluated.

The DE 196 35 968 describes an arrangement and method for automatically determining crack resistance curves. In this case, a test specimen is provided as well as a test specimen storage and a force sensor system or a path-time sensor system and a special crack length calculation software. The DE 10 2004 061 796 A1 describes a micromechanical capacitive sensor element. This sensor element is produced in monolithic integrable construction and allows a capacitive detection of a physical characteristic.

From the DE 271 81 94 is a multilayer monolithic ceramic capacitor known. The DE 10 2007 011 817 A1 describes a method and apparatus for locating faults on capacitive sensor electronic circuit boards. In the process, test parameters are determined and these in turn are compared with reference parameters. The applied signal or the signal measured at the circuit is coupled directly to the printed circuit board and coupled out of this and the other signal coupled out via a capacitive coupling from the circuit board or coupled into this. In this way, it is possible to detect errors of the electronic circuit board in its entirety. However, no malfunction or failure of certain electronic components arranged on these printed circuit boards can be detected in this way. In addition to the term PCB also the term circuit carrier can be used

Of the The present invention is therefore based on the object, a device and a method for testing electronic components and In particular, such components that are already on printed circuit boards or Circuit carriers are arranged available to deliver. In particular, a device and a method be provided, which is a non-destructive Allow testing of the corresponding component.

Farther are known from the prior art method, which is a bend a printed circuit board, for example via strain gauges (DMS) and indirectly on the bending load of the electronic Close component. Another task of the present The invention therefore consists in providing a method to provide a direct measurement of the corresponding electronic Component (possibly even if this is not arranged on a circuit board is allowed.

These Tasks are inventively by the objects reached the independent claims. advantageous Embodiments and developments are the subject of Dependent claims.

In a method according to the invention for examining electronic components, the electronic component to be examined is mechanically stressed. According to the elek to be examined tronic component turned on in an electronic circuit, subjected to an electrical signal and measured at least one electrical characteristic of the electrical circuit, wherein the electronic component to be examined is integrated into the electrical circuit such that the mechanical stress of the component influences the electrical characteristic.

in the Contrary to the indirect measuring methods described above therefore in the inventive method the Component to be examined, such as a ceramic capacitor, integrated directly into a circuit and by the mechanical load occur, in particular, if the capacitor is already faulty, corresponding signals to the user about this Orient errors. In this way, a non-destructive Test of the electronic component can be achieved. Used with it the inventive method the electronic Component or the capacitor itself as a sensor whereby a falsification the results of an indirect collection method are eliminated.

through this process according to the invention can Cracks are detected by a fineness, which by means of previous electronic methods such as insulation resistance measurements or capacity measurements were not possible. These measuring methods only detect a far advanced state of damage said components.

Farther also becomes by the method according to invention a graphic analysis of the behavior of electronic components as capacitors allowed, which was previously not possible. This analysis can also be used to characterize the component or to be used for technology improvement. Furthermore, that can inventive method, in example by Modification of a measuring chain, for the examination of others electrical or physical quantities of electronic components be used.

at In a preferred method, the electronic component is on a Surface and arranged in particular a circuit board and preferably soldered. This is the integration simplified in an electronic circuit and also the implementation the bending load on the electronic component easier. Preferably, the electronic component is a ceramic capacitor and in particular an SMD (Surface Mounted Device) capacitor. In these multilayer capacitors were so far Errors such as cracks are very difficult to detect.

Preferably the electrical circuit is an oscillator and particularly preferred is the component to be tested as Element built into this oscillator. That way is one very sensitive measurement of faulty behavior of the tested electronic component possible.

at Another preferred method is the electrical property of the circuit a frequency of the circuit. This means, that, for example, a frequency of the circuit is measured and from this measurement it can be concluded whether the one to be examined Capacitor is faulty. Generally, it is advantageous in the characteristic value by a time-dependent change Size.

at a further advantageous method is a component carrying the Printed circuit board mechanically stressed and in particular bent. By this bending, which strictly controls the degree can also be charged mechanically, the capacitor itself. In the presence of cracks, this manifests itself in the very much from the circuit or capacitor output signal sensitive.

Preferably the electronic component is mechanically loaded such that caused by the load no destruction of the component becomes. On the other hand, however, already existing damage of the component, for example, cracks, even by this comparatively low mechanical load can be detected.

Preferably the electronic component becomes during the mechanical Load not touched by a load element. So For example it is possible that the loading element Although contacted the circuit board or board, but not the arranged on this circuit board capacitor, since this respect of the loading element on the opposite side the circuit board is arranged.

Preferably, the electrical characteristic value is measured during the mechanical loading of the electronic component. If necessary, it would also be conceivable to measure the electrical characteristic immediately after the mechanical load on the electronic component, for example, when the printed circuit board moves back into an initial state. When relieving during the return movement in the Initial state of the characteristic is preferably further evaluated, which may provide additional information about the behavior of the component (or including the structure), such as a hysteresis.

at a further advantageous method is a characteristic value as a relative value issued, d. H. it will not be absolute size spent for the circuit but a comparison found between a reference, which is an intact electronic component and the value indicating a component that is no longer intact. For example, by specifying a corresponding measure, as a standard deviation or the like checked whether a component is within certain load capacities.

The The present invention further relates to a device for inspecting electronic components with a mechanical Loading device, which is the electronic component to be examined at least indirectly mechanically loaded. According to the invention the device comprises an electrical circuit in which the electronic Component is integrated and a measuring device for measurement an electrical characteristic of this circuit or the component. In this case, the electronic component to be examined is in the electrical circuit that integrates the mechanical load of the component affects the electrical characteristic. Especially influences the mechanical load of the component on the electrical Characteristic value if this electronic component is damaged is.

at A preferred embodiment is the measuring device a frequency counter. However, it would also be appropriate other measuring devices such as voltage measuring devices and the like. conceivable.

at a preferred embodiment contains the Measuring device an oscillator, a frequency counter and a data evaluation unit (for example, PC). It would be but also measuring equipment with possibly other devices such as measuring bridges, voltage measuring devices and the like. conceivable.

Advantageous the electronic component is a component which consists of a group is selected from components, which capacitors, in particular ceramic capacitors, resistors, inductive elements, piezoelectric Elements and the like. Contains. In particular, it is at the electronic component to a passive component.

Advantageous The electrical circuit has a voltage source which the component to be tested with a voltage and in particular a time-dependent signal applied. Especially advantageous The electrical circuit generates a time-dependent Voltage as a measuring signal with which the component to be tested is charged.

at a further advantageous embodiment, the electronic circuit also an inductive element like a coil, R-C members or the like on. Advantageously, it is in the electrical Circuit around an oscillator, in which said capacitor is integrable.

at Another preferred embodiment, the device a storage for a circuit board on which to testing component is arranged.

Advantageous the device has a loading element for exercise the mechanical load, with this loading element opposite the electronic component or said circuit board movable is. Advantageously, the loading element is perpendicular to the circuit board or also perpendicular to the plane movable.

Further Advantages and embodiments will be apparent from the attached Drawings:

In this demonstrate:

1 a schematic representation of a soldered on a circuit board ceramic capacitor;

2 a schematic representation of a mechanical test recording of the electronic component;

3 a schematic representation of a device for examining the electronic component;

4a . 4b two representations of a detected signal

1 shows a schematic representation of a on a board or printed circuit board 12 arranged electronic component 1 like here a ceramic capacitor. This ceramic capacitor has two connections 22 and 24 on, on each of which electrodes 32 respectively. 34 are arranged. The reference number 26 refers to a solder joint, by means of which the capacitor on a copper layer 28 the circuit board 12 is arranged. Cracks of the individual electrodes are very difficult to measure with methods known from the prior art and, in particular, can not be measured without destruction of the capacitor.

2 shows a schematic representation of an arrangement for loading the capacitor 1 , Here is a load element 14 provided, which is moved along the arrow P1 and the circuit board 12 with the capacitor arranged thereon 1 loaded. In the fully loaded state, the circuit board takes the in 2 shown dashed curve H a. The reference numerals 16 and 18 refer to roller assemblies on which the circuit board is arranged. The printed circuit board is pressed down by a distance X.

The bending also depends on the distance I of the two bearings 16 and 18 from. Thus, a mechanical load in the form of a bending load is exerted here. The inventive method allows the non-destructive detection of the bending behavior and a possible fault condition of the capacitor 1 , Furthermore, it is also possible to estimate the possible damage time under load (eg as a consequence of crack formation) so that the method according to the invention is also suitable for checking the load capacity of ceramic capacitors or also other electronic components. The capacitor or specimen is usually on the circuit board 12 he soldered both as a pattern in the case of 1 can be soldered or in his actual application or an existing circuit.

The inventive method can thus application find in electronics manufacturing or even in the development of Printed circuit boards, in capacitor manufacturing and quality management, wherein each of these areas with integrity as well as with the mechanical stress of ceramic capacitors is. In practical applications you can often use the already stocked ones Measure capacitors without directly having a reference pattern to have to.

As mentioned above, in industry, to detect the level of mechanical stresses, strain gauges (DMS) are usually applied to the printed circuit board near or on the reverse side of the affected electronic component 1 glued. The disadvantage here is that while measuring the bending of the circuit board, but not the actual mechanical stress on the capacitor and therefore can only estimate derived. In addition, the integrity of the capacitor is not tested.

other Previous electrical methods such as the insulation resistance or Capacitance measurements are only becoming advanced Damage level of the test object meaningful. The inventive method and the invention On the other hand, devices allow the definition of even very fine cracks.

3 shows a circuit arrangement or device 10 to check the capacitor. Here is the capacitor to be tested 1 via connecting lines 5 in an electrical circuit 2 built-in. This circuit 2 is supplied via a (not shown) power supply and has next to other electronic components such as resistors, semiconductor devices and, if necessary. Inductors. Thus, in the method according to the invention or the device according to the invention, the capacitor to be examined itself is used here as a sensor in order to detect its own mechanical load.

at the soldered on a circuit board rectangular ceramic Capacitor is mainly the bend of its long side of interest. If necessary, however, can deviate Biegerungen, in particular by means of correction factors, evaluated become. For example, it would be possible to twist the circuit board, or in another direction too bend. Also could be beside or instead of mechanical Effects also other effects on the electronic component, such as the effects of strong electromagnetic Fields, temperature effects, cold effects, vibrations and Like. Be used for examinations of the electronic component.

The capacitor to be tested is in the electrical circuit 2 or resonant circuit of an electrically suitable oscillator, in which it acts in particular frequency determining. This oscillator is advantageously carried out sufficiently frequency stable and has in particular a short-term stability of less than 10 ^-4 / min. Due to the in 1 As shown in the layer structure of the capacitor, the mechanical bending leads to a slight change in capacitance, which is due to the oscillation frequency of the oscillator 2 out acts. About the measuring device 8th , which is in particular a digital frequency measuring device and a subsequent mathematical processing of the measured values with a computer by means of software, a temporal representation of the mechanical bending process is made possible. There is a proportionality between a degree of bending and the frequency deviation or the rash. In conventional bends in particular also has a good linearity.

The method according to the invention or the device 10 provides graphically two important information. On the one hand, the mechanical degree of bending of the capacitor can be determined in still undamaged condition and possibly also the entry moment of irreversible damage, for example, cracks or fractures.

The 4a and 4b show two representations resulting from the measurement of a capacitor. It is in 4a a representation for an undamaged capacitor shown. It can be seen here on the smooth rash or the smooth time course of the signal that the circuit has a certain nominal frequency.

At the in 4b The picture shown can be seen a variety of rashes, which indicate a damaged capacitor or a capacitor with cracks. The reference number 42 always refers to a zero line.

Preferably, the method according to the invention provides relative values, since software can be used to perform manual zero suppression before each measurement task. Calibration is possible based on reference patterns in most cases. Due to the oscillator circuit used 2 and mathematical signal processing, capacitors with a very wide capacitance range of approx. 500 pF to approx. 5 μF are to be investigated. However, this area can be extended by appropriate circuit adjustments.

As in 3 Therefore, the entire measuring arrangement is shown in the order of the electronic component to be examined 1 , the oscillator 2 , a digital frequency counter 8th and the PC 11 with software. However, the measurement chain can also be varied in order to allow investigations on stability and mechanical behavior of other electronic components, such as resistors, inductors or piezoelectric components.

The present invention is further directed to software for evaluating the signals output by the measuring devices. This evaluation software allows, for example, a zero suppression, which is a remaining zero line from the beginning of the measurement, regardless of the nominal value of the DUT 1 or the influence of external interference factors, eg. As the temperature ensures.

Farther The said software also allows the conversion of the graphic or numerical output in relative values (eg% values). So can For example, as relative values for a scatter or Variance of the output characteristic or signal can be used.

Furthermore, the software can also take over the entire graphic design of the screen as well as the construction of diagrams and virtual operating elements. For small bends, the formulas below can be used for signal conditioning:

A denotes the above-mentioned output value (characteristic value) or the deflection, f the oscillation frequency, Δf the frequency change, C the capacity of the specimen, ΔC the capacitance change, k a scaling constant, a a constant for zero-value suppression, k1 the bending constant of the test design, Δx den Bending path (cf. 2 ) and l the PCB length.

All Features disclosed in the application documents are considered to be essential to the invention as far as they are individually or in combination the prior art are new.

1

Capacitor, component

2

Circuit / oscillator circuit

5

interconnectors

8th

measuring device

10

circuitry or device

12

Circuit board, circuit board

14

loading element

16 18

overlays

22 24

connections

26

soldered point

28

copper layer

32 34

electrodes

42

zero line

P1

arrow

X

distance

H

course

A

characteristic value

C

capacity of the test piece

k1

deflection constant the test construction

Ax

deformability

l

PCB length

f

oscillation frequency

.delta.f

frequency change

.DELTA.C

capacity change

k

scaling constant

a

constant for zero value suppression

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 2404570 [0004]
• - DE 19635968 [0005]
• DE 102004061796 A1 [0005]
• - DE 2718194 [0006]
• DE 102007011817 A1 [0006]

Claims (15)

Method for inspecting electronic components ( 1 ), wherein the electronic component to be examined ( 1 ) is mechanically loaded, characterized in that the electronic component to be examined ( 1 ) in an electrical circuit ( 2 ) is switched on, is applied to an electrical signal and at least one electrical characteristic value (A) of the electrical circuit ( 2 ), wherein the electronic component to be examined ( 1 ) in the electrical circuit ( 2 ), that the mechanical load of the component ( 1 ) influences the electrical characteristic (A). Method according to claim 1, characterized in that the electrical component ( 1 ) on a printed circuit board ( 12 ) is arranged. Method according to at least one of the preceding claims, characterized in that the electrical component ( 1 ) is a ceramic capacitor. Method according to at least one of the preceding claims, characterized in that the electrical circuit is an oscillator ( 2 ). Method according to at least one of the preceding claims, characterized in that the electrical property of the circuit ( 2 ) a frequency of the circuit ( 2 ). Method according to at least one of the preceding claims, characterized in that a printed circuit board carrying the component ( 12 ) is mechanically stressed and in particular bent. Method according to at least one of the preceding claims, characterized in that the electrical component ( 1 ) is mechanically stressed such that the load does not damage the component ( 1 ) is caused. Method according to at least one of the preceding claims, characterized in that the electrical component ( 1 ) during the mechanical load not from a loading element ( 14 ) is touched. Method according to at least one of the preceding claims, characterized in that the electrical characteristic value (A) during the mechanical loading of the electronic component ( 1 ) is measured. Method according to at least one of the preceding Claims, characterized in that as characteristic value (A) a relative value is output. Contraption ( 10 ) for examining electronic components with a mechanical loading device ( 6 ), which the electronic component to be examined ( 1 ) mechanical load, characterized in that the device ( 10 ) an electrical circuit ( 2 ) into which the electronic component ( 1 ), and a measuring device ( 8th ) for measuring an electrical characteristic value (A) of the circuit ( 2 ), wherein the electronic component to be examined ( 1 ) in the electrical circuit ( 2 ) is integrated, that the mechanical stress of the component ( 1 ) influences the electrical characteristic (A). Contraption ( 10 ) according to claim 10, characterized in that the measuring device ( 8th ) is a frequency counter. Contraption ( 10 ) according to at least one of the preceding claims, characterized in that the electronic component ( 1 ) is a component selected from a group of components including capacitors, particularly ceramic capacitors, resistors, inductive elements, piezoelectric elements, and the like. Device according to at least one of the preceding claims, characterized in that the device has a bearing ( 16 . 18 ) for a printed circuit board ( 12 ) on which the component to be tested ( 1 ) is arranged. Device according to at least one of the preceding claims, characterized in that the device is a loading element ( 14 ) for exerting the mechanical load, said loading element ( 12 ) relative to the electrical component ( 1 ) is movable.