JP2007108110A - Substrate inspection method and substrate inspection apparatus - Google Patents

Abstract

An object of the present invention is to enable inexpensive inspection of a substrate in which electrodes electrically connected via via holes are arranged on both sides or a substrate in which conductive paste is filled in via holes.
A temperature variable means for heating or cooling a multilayer wiring board having electrodes 2a and 2b arranged on both sides of a first surface and a second surface electrically connected via via holes, and a multilayer A thermography (temperature) for measuring the temperature distribution of the second surface 1b of the multilayer wiring board 1 heated or cooled by the temperature variable means 3 and the substrate contact means 9 for bringing the first surface 1a of the wiring board 1 into close contact with the temperature variable means 3. Distribution measurement means) 4 and quality determination means 8 for determining quality of the connection state between the electrodes on both sides based on the temperature distribution measured by the thermography 4.
[Selection] Figure 1

Description

  The present invention relates to an inspection method and an inspection apparatus for a substrate in which electrodes electrically connected via via holes are arranged on both sides, or a substrate in which a conductive paste is filled in via holes.

  In recent years, in the electronic industry field, with the demand for precision, miniaturization, and high density, circuit boards constituting electronic devices are also required to be precise, small, and high density. In order to meet these demands, the wiring of the circuit board is made finer, and a multilayer wiring board that performs electrical connection between layers through via holes is used. Furthermore, a component-embedded substrate that incorporates electronic components and semiconductor elements inside the substrate is being introduced.

  A multilayer wiring board is composed of a plurality of wiring layers that transmit electrical signals and an insulating layer for insulating each wiring layer. In order to perform interlayer wiring between each wiring layer, a via hole is provided in the insulating layer. Wiring connection (via contact) is performed. A problem associated with miniaturization of wiring and via holes is poor connection of via contacts due to disconnection of wiring and abnormal shape of via holes.

  As a substrate quality inspection method, there is a method in which an inspection pin is applied to an electrode portion of a substrate to obtain a resistance value. However, inspection variations due to poor contact of the inspection pins occur. Further, it is difficult to miniaturize the inspection pin in accordance with the miniaturization of the substrate wiring. Further, the manufacturing cost of the inspection pin increases. Furthermore, it is necessary to reset the position of the inspection pin each time the design of the substrate is changed. In addition, the number of points to be inspected has increased, and the inspection takes time. Also, the inspection causes damage such as scratches on the wiring. Various problems as described above have occurred.

  In Patent Document 1, a semiconductor chip flip-chip mounted on a printed circuit board is heated by laser light irradiation, the temperature distribution of the heated semiconductor chip is measured by thermography, and each pad of the semiconductor chip and these are measured based on the measurement result. An inspection method for inspecting a connection state with each land of a printed circuit board corresponding to the above is disclosed. When the connection between the pad and the land is normal, the inspection principle is that the heat of the heated semiconductor chip is transmitted from the pad through the land to the substrate and the temperature of the same part becomes lower than the other part. When the temperature is in the normal range, the connection between the pad and the land is considered normal, and when the temperature is in the abnormal range, the connection failure is detected by assuming that the connection is not normal.

  However, only circuits connected to the semiconductor chip can be inspected, and other circuits cannot be inspected. Further, when there is an abnormality in the substrate, it is difficult to repair the mounted semiconductor chip (replacement with a non-defective product), so that the substrate and the semiconductor chip are effectively discarded, resulting in an increase in cost. Furthermore, in the case of a substrate that electrically connects the substrate and the semiconductor chip via a bonding wire or the like, the connection distance becomes long and the heat conduction becomes small, so that it is difficult to use.

  In Patent Document 2, a semiconductor chip in an energized state is picked up by a visible light camera from above and picked up by an infrared light camera from below, and if a defective portion of an integrated circuit generates heat, it is obtained by both cameras. An inspection method for specifying the location based on the image signal is disclosed. This inspection method is based on the inspection principle that an abnormal current flows through a defective portion when energized to generate heat. When heat is generated, a defective product is detected by specifying the location.

  However, all the circuits on the board to be inspected need to be electrically connected for energization, and the inspection cost increases with the miniaturization of the board and the increase in the number of inspection pins. Further, it is necessary to reset the position of the inspection pin every time the design of the substrate is changed.

  Moreover, in the case of a substrate having a via hole that is insufficiently filled with the conductive paste, poor conduction is likely to occur after the substrate is multilayered. Conventionally, as a method for inspecting a substrate in which a via hole is filled with a conductive paste, an illumination light is irradiated obliquely from above to the via hole in a state where the conductive paste is uncured, and the surface of the conductive paste has a dent. A method is known in which the shape of a dent is obtained based on the size of a shadow that can be formed according to the degree, and a defective product is detected.

  However, since it is necessary to measure all the via holes to be inspected one by one in order to measure the shape of the recess of the conductive paste, it takes time for the inspection. Further, although the dent on the surface of the via hole can be observed, it cannot be detected even if there is a foreign matter mixed in the via hole or a filling defect such as a void.

  Further, Patent Document 3 discloses that a substrate having a via hole filled with a conductive paste is irradiated with X-rays, and the amount of X-rays transmitted is measured. An inspection method for detecting the presence or absence is disclosed. This is based on the fact that there is a difference between the X-ray absorption amount when the paste filling state is normal and the X-ray absorption amount when there is an abnormality in the filling state or there is a foreign substance inside, and the filling state The quality is determined. However, an X-ray source and a detector are necessary, and the inspection apparatus cost increases.

  In Patent Document 4, a via hole portion of a substrate in which a conductive paste is filled in a via hole is heated by laser or electromagnetic induction heating, infrared light emitted from the conductive paste is detected, and the amount or time of the infrared light is detected. A method for detecting the filling state of the conductive paste by measuring the amount of change is disclosed.

However, the heating of the laser requires an inspection time to heat the conductive paste one point at a time, and the inspection cost increases because the laser device is expensive. In the case of heating by electromagnetic induction heating, copper or silver is mainly used as the conductive particles of the conductive paste. However, these conductive particles have a low heat resistance, and thus generate a small amount of heat and require a long heating time.
Japanese Patent Laid-Open No. 11-201926 (pages 4-5 and 6-8) Japanese Patent Laid-Open No. 10-142066 (page 4-5, FIG. 1) JP 2000-55834 A (page 3, Fig. 1-2) Japanese Patent Laid-Open No. 11-304740 (page 2-4, FIG. 1-7)

  In the case of a method for inspecting a substrate in which electrodes electrically connected via via holes are arranged on both sides, it is necessary to inspect via holes and wirings arranged inside the substrate. As described above, inspection has become difficult as the substrate is miniaturized and the number of circuits is increased, and a method for inspecting the entire substrate or a desired portion at once without mounting inspection pins or components is desired. Yes.

  The same applies to the method of inspecting a substrate in which a via hole is filled with a conductive paste, and the whole or desired portion of the substrate can be made cheap at a time with respect to the filling state of the conductive paste and the filling state of the surface and the inside. A method of inspection is desired.

  On the other hand, the whole or a desired portion of the substrate can be quickly and collectively inspected by an inspection method AOI (Automatic Optical Inspection) of the wiring on the substrate surface. This is largely due to the improvement of the imaging device technology and the improvement of the technology of a computing device that determines whether or not the imaging device is normal. However, the wiring and via holes inside the multilayer wiring board cannot be observed by AOI.

  The present invention has been made in view of such a point, and can inexpensively inspect a substrate in which electrodes electrically connected via via holes are arranged on both surfaces, or a substrate in which via holes are filled with conductive paste. It is an object of the present invention to provide an inspection method and an inspection apparatus that can perform inspection.

The method for inspecting a substrate according to the present invention is a method for inspecting a substrate in which electrodes electrically connected via via holes are arranged on both the first surface and the second surface,
Contacting the first surface of the substrate with a temperature variable means for heating or cooling and heating or cooling the first surface;
Detecting the temperature of the electrode on the second surface of the substrate, and determining the quality of the connection state between the electrodes on the both surfaces based on the detected temperature.

  A conductive material is used for the electrode of the substrate to be inspected, and its thermal conductivity is high. On the other hand, the thermal conductivity of the insulating material of the substrate is low. The heat of heating the first surface of the substrate is conducted from the electrode on the first surface through the conductive portion of the via hole, so that the temperature of the electrode on the second surface rises quickly. Since the insulating material has a large thermal resistance, it takes time to increase the temperature. If a connection failure such as disconnection occurs somewhere in the conductive portion from the first surface electrode to the second surface electrode, the thermal resistance increases and the rate of temperature rise slows down. The first surface of the substrate is brought into close contact with the temperature variable means to reduce the thermal resistance between them as much as possible so that the temperature change becomes as steep as possible. By using such characteristics to detect the temperature of the electrode on the second surface, it is possible to efficiently determine whether or not the connection state of the conductive portion from the electrode to the electrode is good.

Further, the substrate inspection method according to the present invention is a substrate inspection method in which a conductive paste is filled in via holes,
Contacting the first surface of the substrate with a temperature variable means for heating or cooling and heating or cooling the first surface;
Detecting the temperature of the conductive paste on the second surface of the substrate, and determining whether the state of filling of the conductive paste is good based on the detected temperature.

  The thermal conductivity of the conductive paste is sufficiently high compared to the insulating material. The heat of the first surface of the substrate is conducted through the conductive paste in the via hole, so that the temperature of the paste surface on the second surface rises quickly. Since the insulating material has a large thermal resistance, it takes time to increase the temperature. If there is a foreign matter, void, or the like inside the conductive paste and there is a poor filling of the conductive paste, the thermal resistance will increase and the rate of temperature rise will be slow. The first surface of the substrate is brought into close contact with the temperature variable means to reduce the thermal resistance between them as much as possible so that the temperature change becomes as steep as possible. By using such characteristics and detecting the temperature of the conductive paste on the second surface, it is possible to efficiently determine the quality of the state of filling of the conductive paste.

  In the above, the conductive paste filled in the via hole may be in an uncured state. Even if it is determined to be defective by inspection, since it is in an uncured state, it can be refilled with a conductive paste and can be repaired (replaced with a non-defective product). Moreover, since a defect can be discovered before a hardening process and a defective sample can be detected without passing through a subsequent hardening process, productivity improves.

  Further, in the substrate inspection method described above, there is an aspect in which heating and cooling are alternately repeated in a pulse shape, and pass / fail is determined based on a temporal change in temperature. According to this, even if there is a part where the thermal resistance is considerably large and the temperature change amount is extremely smaller than the normal part, it is determined whether or not it is normal based on the differential value which is the temporal change amount of the temperature. As a result, it is possible to make a pass / fail judgment with higher accuracy.

Further, the substrate inspection apparatus according to the present invention includes:
Temperature variable means for heating or cooling a substrate in which electrodes disposed on both sides of the first surface and the second surface are electrically connected via via holes;
Substrate contact means for bringing the first surface of the substrate into close contact with the temperature variable means;
Temperature distribution measuring means for measuring a temperature distribution of the second surface of the substrate heated or cooled by the temperature variable means;
It is configured to include a quality determination unit that determines quality of the connection state between the electrodes on both sides based on the temperature distribution measured by the temperature distribution measurement unit.

  The first surface of the substrate is brought into close contact with the temperature variable means by the substrate contact means to reduce the thermal resistance between them as much as possible, and then the temperature variable means is driven to heat or cool the first surface of the substrate. Heat is conducted through the conductive portion of the via hole, and the temperature of the electrode on the second surface changes. The temperature distribution of the second surface is measured by the temperature distribution measuring means, and the quality determining means determines the quality of the connection state of the conductive portion between the electrodes based on the temperature distribution of the measurement result.

  As described above, since the difference in temperature change caused by the large difference between the thermal conductivity of the electrode material and the thermal conductivity of the poor connection of the insulating material and the conductive part between the electrodes is used, the connection state of the conductive part between the electrodes is good or bad The determination can be performed efficiently.

Further, the substrate inspection apparatus according to the present invention includes:
A temperature variable means for heating or cooling the substrate filled with the conductive paste in the via hole;
Substrate contact means for bringing the first surface of the substrate into close contact with the temperature variable means;
Temperature distribution measuring means for measuring a temperature distribution of the second surface of the substrate heated or cooled by the temperature variable means;
It is configured to include a quality determination unit that determines the quality of the filling state of the conductive paste based on the temperature distribution measured by the temperature distribution measurement unit.

  The first surface of the substrate is brought into close contact with the temperature variable means by the substrate contact means to reduce the thermal resistance between them as much as possible, and then the temperature variable means is driven to heat or cool the first surface of the substrate. Heat conducts the conductive paste, and the temperature of the paste surface on the second surface changes. The temperature distribution of the second surface is measured by the temperature distribution measuring means, and the quality determining means determines the quality of the conductive paste filling state based on the temperature distribution of the measurement result.

  As described above, since the difference in temperature change caused by the large difference between the thermal conductivity of the conductive paste and the thermal conductivity of the insulating material and the poorly filled portion of the conductive paste is used, it is possible to judge whether the conductive paste is filled or not. It can be done efficiently.

  In the above, it is preferable that the temperature distribution measuring unit is a thermography. Since thermography is a non-contact type sensor, it can detect a wide range of temperature distribution at a time and is excellent in productivity. In addition, unlike a contact type sensor, even if the shape of the substrate and the wiring arrangement position change, it is not necessary to change the sensor, so that the productivity is excellent.

  Further, in the above, there is an aspect in which a porous material is interposed between the temperature variable means and the substrate filled with the conductive paste.

  If the conductive paste adheres to the temperature variable means, the conductive paste may further adhere to the insulating material of the substrate and cause insulation failure. By inserting a porous material between the temperature variable means and the substrate, insulation failure can be prevented. In general, the adhesion of the substrate to the temperature variable means is performed by an adsorption mechanism, but the insertion of the porous material is effective for transmitting the suction force.

  In addition, when the conductive paste is uncured, the resin component in the conductive paste penetrates into the porous material and enhances the adhesion between the substrate and the porous material. When the resin material penetrates into the pores of the porous material, the thermal conductivity of the porous material in the portion where the resin has penetrated increases. Furthermore, since the adhesion between the porous material and the conductive paste is also strengthened, there is an effect that the thermal resistance between the conductive paste portion and the temperature variable means is selectively lowered, and the temperature change to be detected is increased.

  Further, in the above, there is an aspect in which the via hole is further provided with a filling unit that fills the conductive paste. By performing the substrate inspection following the filling of the conductive paste, the substrate transport step can be omitted, and the productivity can be improved. Furthermore, when it is determined to be defective at the time of inspection, repair can be performed by performing the filling process again, and productivity is improved.

  According to the present invention, the thermal conductivity of the electrode material or conductive paste and the insulating material is detected by detecting the temperature of the electrode or conductive paste on the second surface opposite to the heated or cooled first surface. By using the difference in thermal conductivity between the difference in the quality and the quality of the connection and the quality of the filling, it is determined whether the electrodes are normally connected or whether the conductive paste is normally filled. Inspection can be performed without being affected by the wiring pattern, arrangement and density, and inspection with excellent productivity can be realized.

  Embodiments of a substrate inspection method and a substrate inspection apparatus according to the present invention will be described below in detail with reference to the drawings. In the following drawings, components having substantially the same function are denoted by the same reference numerals for the sake of simplicity. Note that the present invention is not limited to the following embodiments.

(Embodiment 1)
A substrate inspection method and inspection apparatus according to Embodiment 1 of the present invention will be described with reference to FIG. In FIG. 1, 1 is a multilayer wiring board to be inspected, 3 is a temperature varying means for heating or cooling the lower surface (first surface) of the multilayer wiring board 1, and 4 is a lens 5, an infrared detector 6 and heat. A thermography as a temperature distribution measuring means composed of an image processing device 7 for processing an image, 8 analyzes the temperature difference detected by the thermography 4, and an electrode between the first surface and the second surface of the multilayer wiring board 1 It is a pass / fail judgment means (a pass / fail judgment computer) for judging pass / fail of the inter-conductive portion (or conductive paste).

  As the infrared detector 6, a thermal detector, a photoconductive detector, a quantum detector, or the like can be used. Here, in the thermal detector, the temperature of the detector rises due to infrared irradiation, and the effect (change in electrical resistance, capacitance, electromotive force, volume, spontaneous polarization, etc.) due to this temperature rise is converted into an electrical signal. And take it out. The photoconductive detector uses a semiconductor and detects the amount of infrared irradiation from the change in the conduction band caused by free electrons and holes generated by infrared irradiation. The quantum detector detects the irradiation amount of infrared rays from the electromotive force generated when infrared photons are irradiated to the PN junction. In actual measurement, infrared rays radiated from the multilayer wiring board 1 are captured through the wide-angle lens 5 attached to the infrared detector 6, and a detection signal is sent to the image processing device 7.

  In the substrate inspection method according to the present embodiment, heat from the temperature varying means 3 is applied to the multilayer wiring substrate 1 to be inspected, and a temperature distribution image of the multilayer wiring substrate 1 is taken into the thermography 4. A difference appears in the temperature of the conductive part between the electrodes and the temperature of the insulating material part due to the difference in thermal conductivity between the electrode material and the insulating material. A temperature difference also occurs depending on whether the connection state between the conductive portions between the electrodes is normal or defective. Subsequently, the temperature difference detected by the thermography 4 is analyzed by the pass / fail determination means 8 to determine whether the product is good or defective.

  Incidentally, the electrode material is generally a conductive material such as copper, silver or an alloy thereof. Its thermal conductivity is about 300 to 400 W / mK, which is very high. On the other hand, the insulating material is made by impregnating a core material such as glass fiber with a resin material such as epoxy resin, and its thermal conductivity is about 0.1 to 0.5 W / mK. The ratio of thermal conductivity of both is about 1000 times.

  Next, the configuration of the substrate inspection apparatus according to the embodiment of the present invention will be described with reference to the drawings.

  In FIG. 2, 1a is the first surface which is the lower surface of the multilayer wiring board 1, 1b is the second surface which is the upper surface thereof, 2a is the electrode on the first surface 1a, 2b is the electrode on the second surface 1b, 2c is both electrodes This is an inter-electrode conductive portion connecting 2a and 2b. Reference numeral 9 denotes a substrate contact means for bringing the first surface 2a, which is the lower surface of the multilayer wiring board 1, into close contact with the upper surface of the temperature variable means 3 by decompression suction or the like, and 10 denotes the temperature variable means 3 and the substrate contact means 9. It is a stage.

  The multilayer wiring board 1 is heated or cooled by the temperature variable means 3. The temperature distribution of the second surface 1b of the multilayer wiring board 1 heated or cooled is detected by the infrared detector 6 disposed above.

  FIG. 3 shows a detailed configuration of the image processing apparatus 7. The image processing apparatus 7 includes an A / D conversion unit 11 that converts a signal transmitted from the infrared detector 6 into a digital signal, a control unit 12 that performs environmental temperature correction, emissivity correction, linearization processing, and the like. A thermal image processing unit 13 that generates a thermal image in response to an output signal of the / D conversion unit 11 and a control signal from the control unit 12, and stores 8-bit or 16-bit thermal image data output from the thermal image processing unit 13 An image memory unit 14 for displaying, a display signal processing unit 15 for converting image data read from the image memory unit 14 into a video signal of a thermal image color-coded according to a temperature distribution, and a display signal from the display signal processing unit 15 The display unit 16 is a CRT (Cathode Ray Tube) or the like that projects on a monitor screen.

  Next, an actual detection example will be described.

  First, a multilayer wiring board 1 in which a buildup layer was formed on a glass epoxy substrate and electrodes electrically connected via via holes were arranged on both surfaces of the substrate was produced.

  The multilayer wiring board 1 was placed on the temperature variable means 3 and the substrate contact means 9 was driven to bring the first surface 1 a of the multilayer wiring board 1 into close contact with the upper surface of the temperature variable means 3. Next, the temperature varying means 3 was driven to heat the multilayer wiring board 1. The applied heat was conducted from the electrode 2a on the first surface 1a through the interelectrode conductive portion 2c to the electrode 2b on the second surface 1b, and the temperature of the electrode 2b on the second surface 1b increased.

  In the above, since the multilayer wiring board 1 is brought into close contact with the temperature variable means 3 by the substrate close contact means 9, heat transfer is performed well. If there is a space between the temperature variable means 3 and the multilayer wiring board 1, the thermal resistance becomes high and the temperature change becomes small. The close contact brought about a rapid temperature change, and the inspection could be made highly accurate and efficient.

  More specifically, the temperature of the multilayer wiring board 1 was kept at 25 ° C. before heating. A pulse heater was used as the temperature variable means 3 and heated to 120 ° C. in about 2 seconds, and the temperature change from the time of heating to 3 seconds later was measured. As thermography 4, TVS-8500 manufactured by Avionics was used.

  FIG. 4A shows a schematic diagram of the thermography before heating, and FIG. 4B shows a schematic diagram of the thermography at the time of heating. The pass / fail judgment means 8 performed pass / fail judgment on the connection state of the inter-electrode conductive portion 2c based on the temperature obtained by the measurement and the time variation (differential value) of the temperature. In the non-defective part P1, the ultimate temperature was 80 to 100 ° C., whereas in the defective part P2, it was 70 ° C. or less. Due to this difference, the pass / fail judgment could be performed accurately.

(Embodiment 2)
A substrate inspection method and inspection apparatus according to Embodiment 2 of the present invention will be described with reference to FIG. This is a case where the via hole is filled with a conductive paste.

  In FIG. 5, 17 is a porous material and 18 is a porous material winding device. Reference numeral 19 denotes a conductive paste filling apparatus for filling the via holes of the multilayer wiring board 1 with a conductive paste, 20 denotes a squeegee, and 21 denotes a conductive paste.

  In the conductive paste, a resin material such as epoxy is generally kneaded with copper, silver, or an alloy thereof. The thermal conductivity of the conductive paste is about 5 to 10 W / mK, which is about 100 times that of the insulating material. Since the thermal conductivity of the conductive paste is sufficiently high, the temperature of the paste surface on the second surface can be quickly increased by heating on the first surface of the multilayer wiring board.

  This will be specifically described below.

First, the multilayer wiring board 1 was produced. Its composition is
90% by weight of Al ₂ O ₃ (AS-40 manufactured by Showa Denko KK, spherical, average particle size 12 μm),
9.5% by weight of liquid epoxy resin (manufactured by Nippon Rec Co., Ltd., EF-450),
Carbon black (manufactured by Toyo Carbon Co., Ltd.) is 0.2% by weight,
Coupling agent (Ajinomoto Co., Titanate, 46B) is 0.3% by weight
Met.

  Using these materials, a semi-cured plate was produced (thickness 500 μm). Then, the plate-like body was cut into a predetermined size, a through hole (diameter 0.15 mm) serving as a via hole was formed using a carbon dioxide laser, and the multilayer wiring board 1 was produced.

  The porous material 17 was laid on the upper surface of the temperature variable means 3 by unwinding the porous material 17 from the porous material winding device 18. The multilayer wiring board 1 was placed on the porous material 17. And the board | substrate contact | adherence means 9 was driven, and the multilayer wiring board 1 was stuck to the temperature variable means 3 via the multilayer wiring board 1. FIG.

  Further, the conductive paste 21 was filled into the via hole of the multilayer wiring board 1 with the squeegee 20 in the conductive paste filling device 19. The filled conductive paste 21 penetrated into the porous material 17.

The composition of the conductive paste 21 is
85% by weight of spherical copper particles,
3% by weight of bisphenol A type epoxy resin (manufactured by oil-coated shell epoxy, Epicoat 828),
9% by weight of glycidyl ester epoxy resin (manufactured by Toto Kasei, YD-171),
3% by weight of amine adduct curing agent (Ajinomoto MY-24)
Met. The conductive paste 21 was produced by kneading these materials.

  As the porous material 17, Gore-Tex membrane of Japan Gore-Tex was used.

  FIG. 6 shows a state in which the conductive paste 21 is filled in the via hole in the insulating multilayer wiring board 1.

  The multilayer wiring board 1 in which the via holes were filled with the conductive paste 21 in this manner was then moved to the infrared detector 6.

  Next, the temperature variable means 3 was driven to heat or cool the multilayer wiring board 1 to change the substrate temperature. The multilayer wiring substrate 1 was brought into close contact with the temperature variable means 3 through the porous material 17 by the action of the substrate contact means 9. Since the porous material 17 may have a conductive paste resin, conductive filler, or the like attached thereto, the porous material 17 was wound up by the porous material winding device 18 and supplied with a new porous material.

  In the above, the temperature change is a pulse-like change. The reason for changing the temperature change into a pulse-like change is as follows.

  As the multilayer wiring board 1, a semi-cured one was used. When the temperature rises above a certain temperature, curing proceeds. Therefore, in order to measure at as low a temperature as possible, a pulse-like change is used.

  Further, when both the reached temperature and the temperature change are used for the pass / fail judgment, the measurement may be performed at any timing when the temperature change is made into a pulse shape. As a result, the measurement range can be widened. Further, if the determination is made based on the temperature change, the quality can be determined with high accuracy even if the temperature varies within the surface.

  The multilayer wiring board 1 was heated or cooled, and the temperature distribution was detected by the infrared detector 6 disposed above. The schematic diagram of the detection result by the thermography 4 is shown to Fig.7 (a)-(c). FIG. 7A is a schematic diagram of a case before heating, FIG. 7B is a case of only a non-defective product P3 after heating, and FIG. 7C is a schematic diagram of a case where a defective portion P4 is generated.

  FIG. 8 shows a measurement example. T1 is a temperature variable means temperature, T2 is a non-defective part temperature, T3 is a defective part temperature, and T4 is an insulating substrate temperature.

  The temperature varying means temperature T1 was changed in pulses. In order to suppress the hardening of the conductive paste 21 in the inspection process, the stage temperature was set to 80 ° C. at the maximum. The non-defective part temperature T2 corresponds to the non-defective part P3 in FIG. 7, and the defective part temperature T3 corresponds to the defective part P4. The temperature difference is about 6 ° C. There is a large difference in the rate of change in temperature when the temperature rises and when the temperature falls. Due to this large difference in change rate, it was possible to accurately determine whether or not the conductive paste was filled in the via hole. In addition, what is necessary is just to perform a filling process again, when it determines with the filling of the electrically conductive paste 21 being inferior.

  As mentioned above, although this invention was demonstrated by suitable embodiment, such description is not a limitation matter and of course various changes are possible.

  INDUSTRIAL APPLICABILITY The present invention is useful as an inspection technique for inexpensively inspecting a substrate in which electrodes electrically connected via via holes are arranged on both surfaces, or a substrate in which a via paste is filled with a conductive paste.

The figure which shows the structure of the inspection apparatus in Embodiment 1, 2 of this invention. The figure which shows the test | inspection condition in Embodiment 1 of this invention 1 is a block diagram showing a configuration of an image processing apparatus according to Embodiment 1 of the present invention. Schematic diagram of thermographic image in Embodiment 1 of the present invention The figure which shows the structure of the inspection apparatus in Embodiment 2 of this invention. The figure which shows the condition of the multilayer wiring board in Embodiment 2 of this invention Schematic diagram of thermographic image in Embodiment 2 of the present invention The graph which shows the temperature change of the measurement example in Embodiment 2 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multilayer wiring board 1a 1st surface 1b 2nd surface 2a 1st surface electrode 2b 2nd surface electrode 3 Temperature variable means 4 Thermography (temperature distribution measuring means)
DESCRIPTION OF SYMBOLS 5 Lens 6 Infrared detector 7 Image processing apparatus 8 Pass / fail judgment means 9 Substrate contact | adherence means 10 Stage 11 A / D conversion part 12 Control part 13 Thermal image processing part 14 Image memory part 15 Display signal processing part 16 Display part 17 Porous material 18 Porous Material Winding Device 19 Conductive Paste Filling Device 20 Squeegee 21 Conductive Paste

Claims (9)

A method for inspecting a substrate in which electrodes electrically connected via via holes are arranged on both the first surface and the second surface,
Contacting the first surface of the substrate with a temperature variable means for heating or cooling and heating or cooling the first surface;
Detecting the temperature of the electrode on the second surface of the substrate, and determining the quality of the connection state between the electrodes on both surfaces based on the detected temperature. A method for inspecting a substrate in which a via hole is filled with a conductive paste,
Contacting the first surface of the substrate with a temperature variable means for heating or cooling and heating or cooling the first surface;
Detecting the temperature of the conductive paste on the second surface of the substrate, and determining the quality of the state of filling of the conductive paste based on the detected temperature.   The substrate inspection method according to claim 2, wherein the substrate is an uncured state of the conductive paste filled in the via hole.   The substrate inspection method according to claim 1, wherein heating and cooling are alternately repeated in a pulsed manner, and the quality is determined based on a temporal change in temperature. Temperature variable means for heating or cooling a substrate in which electrodes disposed on both sides of the first surface and the second surface are electrically connected via via holes;
Substrate contact means for bringing the first surface of the substrate into close contact with the temperature variable means;
Temperature distribution measuring means for measuring a temperature distribution of the second surface of the substrate heated or cooled by the temperature variable means;
A substrate inspection apparatus comprising: a quality determination unit that determines quality of the connection state between the electrodes on both sides based on the temperature distribution measured by the temperature distribution measurement unit. A temperature variable means for heating or cooling the substrate filled with the conductive paste in the via hole;
Substrate contact means for bringing the first surface of the substrate into close contact with the temperature variable means;
Temperature distribution measuring means for measuring a temperature distribution of the second surface of the substrate heated or cooled by the temperature variable means;
A substrate inspection apparatus comprising: a quality determination unit that determines quality of the filling state of the conductive paste based on the temperature distribution measured by the temperature distribution measurement unit.   7. The substrate inspection apparatus according to claim 5, wherein the temperature distribution measuring means is a thermography.   The substrate inspection apparatus according to claim 6 or 7, wherein a porous material is interposed between the temperature variable means and the substrate filled with the conductive paste.   The board inspection apparatus according to claim 6, further comprising a filling unit that fills the via hole with the conductive paste.

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