DE10240143B4 - Testing and detection of potential-carrying parts and conductor tracks by means of a film sensor on the basis of stray capacitance measurements - Google Patents

Abstract

Device for testing a component (9), with
A plurality of stray field elements (51, 71), which are arranged for a spatially resolved measurement, for generating and / or measuring a stray field at and / or in the component (9),
- Means for detecting a fault of the electrical component (9) due to the measured stray field, wherein the device and its plurality of stray field elements (51, 71) are formed with
A base layer (3) made of an electrically insulating material,
- A plurality of on the base layer (3) arranged first conductor tracks (5),
A first insulating layer (6) made of an electrically insulating material applied to the base layer (3) and the first printed conductors (5),
A plurality of first electrodes (51) arranged on the first insulating layer (6) and electrically conductively connected via plated-through holes to associated underlying first printed conductors (5),
- A plurality of on the first insulating layer (6) arranged and the first interconnects (5) crossing the second interconnects (7), ...

Description

For the inspection at potential leaders Split and planar circuit traces (Printed circuit boards, thin and Thick film circuits, flexible circuit carriers) are test tips for Detection of conductor interruptions and short circuits used. Such procedures require a lot of testing because numerous connections must be approached with the test tips individually.

at The classical inspection of circuit boards will be a test signal in fed a conductor and then with galvanic and capacitive coupled test probes detected along the conductor tracks. Especially in complex circuits, this process is very complex.

Imaging Inspection procedures are common with regard to the detection of minor defects, such as Hairline cracks, problematic. Systemic risks, such as lack of Contrast sharpness and the required high scan rates, result in optical inspection to inevitable mistakes.

One alternative testing method is using a capacitive CMOS image sensor realized in which the photodiodes exchanged for metal electrodes become. From Scheffer, D .: "Platinum test electrostatically " Elektronik 11/2002, WEKA Fachzeitschriften-Verlag GmbH, Poing, is an imaging inspection method known for the CCDs to capacitive measuring Sensors are rebuilt.

Out GB 2143954 A a device for testing a device is known which has a plurality of stray field elements arranged for a spatially resolved measurement.

From that Starting from the task in the development of an economic and reliable device with high spatial resolution.

These The object is solved by the invention of the independent claim. advantageous Embodiments emerge from the subclaims.

A Device for testing an electrical component, in particular a printed circuit board, thin and Thick film circuit, a flexible circuit board or a board, has a stray field element for generating and / or Measuring a stray field in and / or on the electronic component on. The device thus operates according to the fringing field measuring principle. Furthermore, the device has means for detecting an error of the electrical component due to the measured stray field on. These funds can for example, means for determining an impermissible size of the measured Stray field exist. The invalid Size can by a corresponding circuit or also, as below in detail described by observation observed by a user become.

Should not just big ones Defects of the electrical component, but also, for example, hairline cracks can be measured so it is advantageous if the device means for generating an alternating field at least one potential-carrying Part of the electrical component. Through the device becomes then with the device an active structure with an active Field measured, the potential leading is, for example, by a circuit itself generates a field. So it will be the change of the stray field by introducing another field in the stray field measured. Just defects here become a very strong stray field change cause.

The Means for generating an alternating field at least one potential-carrying Part of the electrical component, for example, as an electrode field be formed on the of the device for testing the electrical component opposite Side of the electrical component can be arranged. This electrode field for generating an alternating field on at least one potential-carrying Part can analogously to the electrode field described below with Stray field elements for generating and / or measuring a stray field be educated. Alternatively, however, the use of conventional Contact tips conceivable to an AC voltage in the electronic to be tested To produce device.

to Generation and / or measurement of the stray field preferably contains the stray field element a pair of electrodes. The control field element can be a pair of electrodes for generating the stray field and a pair of electrodes for measurement of the stray field. However, the stray field element preferably contains a pair of electrodes with which the stray field both generates and can be measured.

Should a flat electrical component tested are, the device is preferably as a stray field sensor formed in the form of a sensor array by a variety of stray field elements used for a spatially resolved measurement the electrical arrangement are arranged.

For contacting the plurality of stray field elements, in particular, the device has in at least two levels crossing interconnects.

is arranged on the plurality of stray field elements and / or in a film, or the device realized as a film, the result is the same several advantages. For example, not only completely planar, but also arched electrical components tested become. Furthermore, the film for testing an electrical component by Vacuum be sucked to the device, so that stray field elements and electrical component always in a defined, tight Distance apart.

To the The above purpose, the device via means for sucking the Foil to the electrical component have.

One Method of testing an electrical component is analogous to the device for testing a electrical component realized. This also applies to preferred Training.

Further Essential features and advantages of the invention will become apparent the description of an embodiment based on the figures. It shows

1 a top view of an apparatus for testing an electrical component,

2 an equivalent circuit diagram in 1 illustrated device;

3 a section along the lines III-III in 1 and

4 the measuring principle of in 1 illustrated device.

1 shows a partial plan view of the device for testing an electrical component, wherein the multilayer structure of the device of the in 3 shown section according to the line III-III can be seen. In the production of the device shown in the figures, it is assumed that a subcarrier, not shown, for example, borosilicate glass. To ensure the adhesion of the subsequent structure on the subcarrier with certainty, an adhesive layer of titanium is applied by sputtering. This adhesive layer then becomes a base layer 3 applied. In the illustrated embodiment, this base layer 3 around a film of a thermostable polymer, for example Kapton, which has a thickness of 50 microns, and is applied by lamination. Subsequently, the base layer 3 planarized by the spin-on of an insulating material, this process in 3 by a separately illustrated planarization 4 is shown.

The subsequent generation of metallic structures in the form of a family of first interconnects 5 can basically be done in subtractive technique, additive technique or semi-additive technique. In the described embodiment, the first interconnects 5 semi-additive produced. On the entire surface with a layer sequence of titanium and palladium sputtered planarization 4 In this case, a not shown in the drawing photoresist is applied and structured so that, for example, galvanic gold or galvanic or chemical copper can be deposited on the free developed circuit pattern. After stripping the photoresist then not the desired first traces are 5 corresponding regions of the layer sequence of titanium and palladium by selective etching to the surface of the planarization 4 eroded.

On the first tracks 5 then becomes a photoimageable first insulating layer 6 applied, in which by exposing and developing holes 61 are introduced, for example, have a diameter of 25 microns. In the subsequent production of a second layer of metallic fine structures in the form of first electrodes 51 , second tracks 7 and second electrodes 71 , then become in the area of the holes 61 Vias generated which the first electrodes 51 with associated underlying tracks 5 electrically conductive connects. The abovementioned second layer of metallic fine structures is again produced semi-additive in the described embodiment. From the schematic representation according to 1 it can be seen that the crowd of first tracks 5 and the bevy of second tracks 7 cross orthogonally. It can also be seen that the second electrodes 71 by extensive broadening of the second interconnects 7 are formed and that the first electrodes 51 and the second electrodes 71 form a pixel field whose pixel pitch can be selected depending on the electrical component to be tested and in particular 70 microns or less, preferably 50 microns or less. The first tracks 5 open end into terminals for transmission lines AS, while the second interconnects 7 lead into connections for receiving lines AE. Via the connections AS and AE, the sensor field is then connected to an evaluation.

2 shows an equivalent circuit diagram of in 1 illustrated device. Between the first tracks 5 and the orthogonally crossing second conductor tracks 7 in each case capacities C are formed. These capacitances C are stray capacitances between adjacent first electrodes 51 and second electrodes 71 , In the described embodiment, C <10 fF. The distance between two electrodes of a pair of electrodes from each other is about 5 microns. The distance between two pairs of electrodes is about 50 microns.

In 3 is again the layer structure of the device with base layer 3 , Planarization 4 , first tracks 5 , first insulation layer 6 , second tracks 7 and second insulation layer 8th and first electrodes 51 and second electrodes 71 clear.

In the described device, the stray field between adjacent first electrodes 51 and second electrodes 71 the sensor field formed by the electrode pairs as a measured variable for testing the electrical component. This principle, also referred to as the fringing field measuring principle, is off 4 seen. Here you can see above the pair of electrodes 51 . 71 and the second insulating layer 8th for passivating the device, the electrical component 9 in the form of a circuit carrier with a potential-carrying part 10 in the form of a conductor track. Between the first electrode 51 and the second electrode 71 of the pair of electrodes of the apparatus for testing the device 9 is generated by applying an AC voltage shown as dotted lines stray field SF. This stray field SF is characterized by the dielectric constant of the component which is changed compared to the dielectric constant of air 9 and its potential-leading part 10 changed in a characteristic way. This already applies if to the potential-carrying part 10 no additional potential has been created yet.

However, the measuring sensitivity can still be significantly increased by adding to the potential-carrying part 10 of the device to be tested 9 In turn, an alternating potential is applied, as in 4 is shown by the dashed potential lines WP.

To the Check For example, the device is described with the described Slide sensor trained device positioned. The foil of the film sensor is then sucked to the electrical component by means of vacuum.

The Sensor surface, the by the plurality of stray field elements in the form of electrode pairs is covered by the size of the testing electrical Component dependent and is for example more than 50 mm × 50 mm and depending on the application also 200 mm × 200 mm or more. Corresponding This results in a field of, for example, 20,000 × 20,000 stray field elements in the form of electrode pairs. These are via a readout electronics read out and the measured values can then over fast A-D converter with 8 bit resolution digitized become. This results in short and economical polling cycles in the μs range realizable.

To the Detecting a fault of the electrical component are the digitized measured values, for example, as a gray scale image. About image processing software, the example over Fourier transform shifts and rotations of the electric Component can filter out Inaccuracies in the positioning of the device over the Device can be eliminated.

Image processing software For example, it can also be used to capture the measurement image of the tested Component with a reference image of an intact component to compare, and thus a possible Fehl er of the device to be tested to detect.

It But it is also conceivable to display the measurement image on a screen and thereby means for detecting to a user of the device a fault of the electrical component due to the measured Streufeldes available to deliver.

In summary the device and the method can be represented as follows: For checking Defects in circuit traces a passive sensor field according to the fringing field measuring principle is used. The sensor field with stray field elements consists of a multi-layer structure in thin-film technology and is executed as a foil sensor. For inspection, the flexible and large sensor field on the zu tested circuit support pressed or sucked the film. Error detection on potential-carrying traces takes place by resulting stray capacitance changes, which in a multi-layer structure be detected with orthogonal crossing electrode structures.

By the constructive design of the sensor field will be a high local resolution less than 50 μm and short pixel polling cycles in the μs range possible. The measuring principle used leads to an extremely high sensitivity to Sreukapazitätsänderungen. At the same time with the manufacturability of large sensor fields of 200 mm × 200 mm or more a very effective and quick inspection of defects guaranteed. The structure of the sensor field on foil allows a inexpensive Manufacturing and the used thin-film technology guarantees a high spatial resolution.

Claims (3)

Device for testing a component ( 9 ), with - a plurality of stray field elements ( 51 . 71 ), which are arranged for a spatially resolved measurement, for generating and / or measuring a stray field at and / or in the component ( 9 ), - means for detecting a fault of the electrical component ( 9 ) due to the measured stray field, the device and its plurality of stray field elements ( 51 . 71 ) are formed with - a base layer ( 3 ) of an electrically insulating material, - several on the base layer ( 3 ) arranged first conductor tracks ( 5 ), - one on the base layer ( 3 ) and the first tracks ( 5 ) applied first insulating layer ( 6 ) of an electrically insulating material, - several on the first insulating layer ( 6 ) arranged first electrodes ( 51 ), which via vias with associated underlying first tracks ( 5 ) are electrically conductively connected, - several on the first insulating layer ( 6 ) and the first interconnects ( 5 ) crossing second tracks ( 7 ), - several on the first insulation layer ( 6 ) arranged second electrodes ( 71 ) associated with associated second traces ( 8th ) are electrically conductively connected, - one on the first insulating layer ( 6 ), the first electrodes ( 51 ), the second tracks ( 7 ) and the second electrodes ( 71 ) applied second insulating layer ( 8th ). Device according to claim 1, characterized in that the base layer ( 3 ) consists of one, in particular flexible, organic material. Device according to one of claims 1 or 2, characterized in that the second electrodes ( 71 ) by extensive broadening of the second interconnects ( 7 ) are formed.