JP4807183B2 - Mounting product inspection method and inspection device - Google Patents

Description

  The present invention relates to an inspection method and an inspection apparatus for an electronic packaging product including an anisotropic conductive film as a bonding material.

  One of electronic mounting methods for mounting a semiconductor package on a printed wiring board, or electrically connecting conductor wirings on two printed wiring boards, and coupling and fixing both printed wiring boards to each other. In addition, there is a method using a film-like anisotropic conductive film.

  For example, when a glass substrate and a semiconductor package are mounted, a semiconductor package in which a plurality of protruding electrodes are arranged to form a connection portion, and a plurality of wiring electrodes that match the pitch of the protruding electrodes and a region in which the semiconductor package is mounted And a glass substrate on which connection portions are formed. Then, with the connecting portions of the two facing each other and the anisotropic conductive film sandwiched between them, the protruding electrodes and the wiring electrodes of both connecting portions are positioned so as to overlap each other in the thickness direction of the film. By performing heating and pressurizing processes while matching, each protruding electrode and the wiring electrode are electrically connected via the conductive particles contained in the anisotropic conductive film, and the adhesive component in the anisotropic conductive film To bond and fix both.

  In the case of connection between a glass substrate and a flexible printed board, a glass substrate and a flexible printed board in which a plurality of wiring electrodes are arranged at respective connection positions at the same pitch to form connection portions are prepared. Then, with the connecting portions of the two facing each other and sandwiching the anisotropic conductive film between them, the electrodes of both the connecting portions are similarly aligned so as to overlap each other in the thickness direction of the film. By performing heating and pressure treatment, each electrode is electrically connected via conductive particles contained in the anisotropic conductive film, and both are bonded and fixed by the adhesive component in the anisotropic conductive film. The

  Examples of the conductive particles contained in the anisotropic conductive film used for electronics mounting are, for example, an average particle diameter of about 0.1 μm to several tens of μm, and the shape is granular, spherical, flaky (scale-like, flake-like) ) And the like have been put into practical use, but recently, linear metal powders having a shape in which fine metal particles are connected in a straight chain are attracting attention.

  By orienting the linear metal powder in the thickness direction of the anisotropic conductive film, the conductivity in the thickness direction of the film can be increased without increasing the filling rate of the conductive particles. For this reason, the connection resistance can be lowered while maintaining the insulation in the surface direction of the film, and the connection reliability is improved. The orientation in the thickness direction means a state in which the longitudinal direction of the linear metal powder is aligned in a direction substantially perpendicular to the film surface.

  In order to improve the connection resistance and connection reliability of a mounted product mounted using an anisotropic conductive film, it is important that more conductive particles are present between the opposing electrodes of the mounted product. For example, in Patent Document 1, the ratio of the metal powder is 0.05 vol% to 20 vol% of the total volume of the film, so that reliable electrical connection between the opposing electrodes can be obtained and A short circuit is prevented.

JP 2003-331951 A

  Using a anisotropic conductive film containing fine linear metal powder described in Patent Document 1, a mounted product in which a glass substrate and a semiconductor package are mounted is confirmed to have the presence of metal powder between electrodes by the following method. Is done. When irradiating light from the light source lamp of the optical microscope toward the protruding electrode of the semiconductor package from the transparent glass substrate side and observing the reflected visible light with an optical microscope, confirm the metal powder present on the protruding electrode Can do. Fine linear metal powder is observed as a black line because the chain diameter is 1 μm or less, but fine irregularities on the surface of the protruding electrode are also observed as black lines. It is quite difficult.

  As another inspection method, there is also a method of cutting the connection part of a mounted product mounted using an anisotropic conductive film, and directly observing the cut surface with a microscope or the like to determine the presence or absence of metal powder. . Although this method is highly effective in confirming the presence of metal powder, it is a destructive sampling inspection of the product and only a small part of the extracted product can be inspected. Is not expensive.

  As described above, since the fine metal powder existing between the electrodes facing each other in the mounted product has a great influence on the connection resistance and connection reliability of the mounted product, the fine metal powder between the electrodes facing each other in the mounted product. There has been a need for a non-destructive and reliable means of inspecting the presence of metal powder, but no such method has been devised so far.

  Accordingly, an object of the present invention is to provide a non-destructive and highly reliable inspection method and inspection of metal powder, that is, conductive particles existing between opposing electrodes of a mounted product mounted using an anisotropic conductive film. To provide an apparatus.

  As a result of intensive research and development to solve the above-mentioned problems, the present inventors have found the following method and apparatus that enable non-destructive inspection of a mounted product mounted with an anisotropic conductive film.

  The present invention is a mounting product inspection method for inspecting the location of conductive particles of a mounted product on which an anisotropic conductive film containing conductive particles is mounted. It is an inspection method for a mounted product, which is bonded through an organic compound and irradiates excitation light on the surface of the mounted product to detect fluorescence emitted from the fluorescent material.

  In the present invention, it is preferable to detect fluorescence emitted from the fluorescent substance using a fluorescence microscope.

  Further, the present invention is a mounted product inspection apparatus for inspecting the position of conductive particles in a mounted product on which an anisotropic conductive film containing conductive particles is mounted, and the conductive particles have a fluorescent material directly or on the surface. An inspection device for a mounted product, which is bonded through an organic compound and includes means for irradiating excitation light on the surface of the mounted product and means for detecting fluorescence emitted from the fluorescent material.

  In the present invention, it is preferable to have means for calculating position coordinate data of the detected fluorescence.

  In this invention, it is preferable to further have a means to determine the quality of a mounted product using the said position coordinate data.

  ADVANTAGE OF THE INVENTION According to this invention, the electroconductive particle which exists between the electrodes which oppose the mounted goods mounted using the anisotropic conductive film can be test | inspected nondestructively.

  First, conductive particles having a fluorescent substance bonded to the surface to be observed will be described. As the conductive particles before the fluorescent substance is bonded, a metal powder having an average particle size of about 0.1 μm to several tens of μm, and having a granular shape, a spherical shape, and a flake shape (flaky shape, flake shape) is used. As a component constituting the metal powder, at least one metal selected from the group consisting of Ni, Fe, Co, Cu, Rb, Rh, Pd, Ag, Re, Pt, and Au, or an alloy thereof is used.

  In order for the conductive particles to emit fluorescence by the action of excitation light, a fluorescent substance is bonded to the conductive particles. Although the fluorescent substance couple | bonded with electroconductive particle is not specifically limited, What is necessary is just to select suitably with excitation light. For example, in the case of excitation at a wavelength near 488 nm, derivatives such as fluorescein and isocyanate, phycoerythrin, dodamine green, GFP (Green fluoresent protein), and the like can be used. When ultraviolet light is excitation light, fluorescent materials such as dansyl chloride, cascade blue, and Hoechst 33342 can be used. In the case of excitation at around 633 nm, allophycocyanin and its derivatives can be preferably used.

  In addition, it is preferable that the fluorescent substance has a functional group because the reaction with the conductive particles and the organic compound proceeds promptly. Examples of suitable functional groups contained in the fluorescent material include isocyanate groups, amino groups, hydroxyl groups, carboxyl groups, sulfonyl groups, epoxy groups, and tosyl groups.

  The fluorescent substance to be bonded to the conductive particles may be directly bonded to the above substance, but may be bonded through an organic compound. The organic compound is not particularly limited as long as it can easily react with the functional group of the fluorescent substance, but avidin, streptavidin, biotin, glutaraldehyde, histidine, and a silane coupling agent can be preferably used. These organic compounds may be used alone or in combination of two or more and may form a complex. When forming the complex, it can be reacted in advance with the fluorescent substance before reacting with the conductive particles.

  Biotin can also be bound to the fluorescent substance. In this case, it is preferable to use avidin or streptavidin as the organic compound. That is, since four molecules of biotin bind to one molecule of avidin or streptavidin, a simple calculation can bind four times as many fluorescent substances. If a plurality of biotins are introduced as a functional group per molecule of fluorescent substance, a complex with avidin or streptavidin is formed, so that more fluorescent substance can be bound to the metal.

An anisotropic conductive film used for mounting will be described. It can be prepared in the same manner as in the case of using a fine metal powder not bound with a fluorescent material, except that the conductive particles are bonded to the fluorescent material. For example, the following two examples are used.
(I) A composite material prepared by blending a fine metal powder and a binder in a predetermined ratio together with an appropriate solvent is applied onto a base and solidified or cured.
(Ii) After a fine metal powder is dispersed on the base, a fluid coating agent containing a binder is applied and solidified or cured.

  As the binder for forming the anisotropic conductive film together with the fine metal powder, any of various compounds having film-forming properties and adhesiveness known as binders in the application can be used. Examples of such a binder include thermoplastic resins, curable resins, and liquid curable resins. Particularly preferable examples include acrylic resins, epoxy resins, fluorine resins, and phenol resins.

  The mounted product mounted using the anisotropic conductive film inspected in the present invention is, for example, a mounted product of a transparent substrate such as glass for liquid crystal display panels and a semiconductor package, or a transparent substrate such as glass and a flexible printed circuit board. Is a suitable combination.

  In the above-described method for manufacturing a mounted product, first, a glass ITO electrode plate in which an electrode having the same number as the IC chip is formed of ITO (Indium-Tin-Oxide), which is a transparent material, is prepared on a glass substrate. After that, the anisotropic conductive film obtained above is sandwiched between the IC chip and the glass ITO substrate, and heat bonding is applied under pressure while heating, and the IC chip and the glass ITO electrode plate are joined. can do.

  Next, the inspection method will be described. FIG. 1 shows a schematic diagram of a mounting product inspection method and apparatus according to the present invention. An excitation light source 11 in which a mercury lamp is generally used emits multicolor light 12 having a wide wavelength from ultraviolet light to infrared light. The excitation filter 13 transmits only the excitation light 14 having a specific wavelength such as ultraviolet light from the multicolor light 12. The dichroic mirror 15 has a property of reflecting light of a specified wavelength and transmitting other light. Therefore, when the excitation light 14 is ultraviolet light, the ultraviolet light is reflected and the other functions are transmitted. The reflected excitation light 14 is collected by the objective lens 16 onto the mounted product 17 to be inspected. Fluorescence 18 is generated from the fluorescent material in the mounting product 17 that has received the excitation light 14. Since the fluorescence 18 is in the transmitted light region of the dichroic mirror 15, it passes through and reaches the absorption filter 19. The absorption filter 19 is provided to remove noise other than light emitted from the fluorescent material. The light transmitted through the absorption filter 19 is observed with the microscope 100.

  There may be irregularities and dust on the mounted product 17, and when the situation on the mounted product 17 is observed with a visible light microscope, conductive particles, irregularities, dust, etc. are also observed. Hard to stick. Therefore, a substance generating fluorescence is combined with the conductive particles so that only the conductive particles are detected, and the conductive particles are extracted by observing the fluorescence.

  The simplest method for determining a mounted product is to confirm that conductive particles are present at a desired position on the electrode in the mounted product by human visual inspection. On the other hand, in order to perform inspection processing in large quantities, at high speed, and unattended, there are means for calculating the position coordinates of the detected fluorescence and means for determining the quality of the mounted product using the position coordinate data. It is preferable to provide.

  Specifically, coordinate axes are provided on a map in which electrode arrangements of mounted products are stored in advance. The image observed by the microscope is read as digital data. Next, the point which shows the brightness exceeding the threshold value provided beforehand is extracted from digital data. Coordinates are calculated using the point as the position where the conductive particles exist. If the number of coordinate points existing at the electrode position on the map is greater than or equal to the specified number, it is determined as “good”. In FIG. 1, a computer 101 is an apparatus provided with both of the above means.

  If the present invention is used as described above, since it is possible to perform non-destructive in-situ observation instead of sampling inspection, the reliability of the inspection result is improved. It can also be automated, and the inspection process can be made more efficient.

(Example)
Hereinafter, based on an Example, this invention is demonstrated further more concretely.

1. Production of linear metal powder 91.5 g (0.30 mol) of trisodium citrate dihydrate and 11.0 g (0.04 mol) of nickel sulfate hexahydrate were dissolved in 715 ml of pure water. Thus, a metal ion solution was prepared. Moreover, as a reducing agent solution, 20 wt% hydrochloric acid aqueous solution (pH 4) of titanium tetrachloride is injected into one tank of a two-tank electrolytic cell partitioned by an anion exchange membrane manufactured by Asahi Glass Co., Ltd. In addition, a sodium sulfate aqueous solution with a molar concentration of 0.1 M is placed in the opposite tank, and a carbon felt electrode is immersed in each solution, with the titanium tetrachloride aqueous solution side serving as a cathode and the sodium sulfate aqueous solution side serving as an anode. A solution of 80.0 g obtained by reducing a part of Ti (IV) to Ti (III) was prepared by conducting a cathodic electrolytic treatment of the aqueous solution by applying a DC current of .5V under constant voltage control. The total amount of titanium ions was 0.1 mol, and the molar ratio of Ti (III) to Ti (IV) was 4: 1.

  Furthermore, in pure water, 60.0 ml of 25% ammonia water and 1.0 g of Serna D-735 (Chukyo oil: polycarboxylic acid type polymer surfactant, component weight ratio: main component = 15-25, ammonia = 1 to 10, water = 65 to 84, main component: styrene-maleic acid copolymer, average molecular weight (W) = 19,000), and then pure water is added as necessary to make the total volume 200 ml. A dispersant solution was prepared by adjusting. The amount of aqueous ammonia was set to an optimum value for adjusting the pH of the entire reaction solution to 10.

  Next, the total amount of the metal ion solution and the total amount of the reducing agent solution are mixed, put in a hot tub and stirred for 20 minutes while maintaining the liquid temperature at 35 ° C., and then between a pair of opposed magnets. The liquid temperature was maintained at 35 ° C. while being placed in the arranged reaction vessel and applying a magnetic field of 100 mT. And while stirring the liquid in a reaction tank 4-5 times with a stirring rod, the whole amount of the dispersant solution that had been heated to 35 ° C. in advance was added all at once, and the reaction liquid was used as described above. After adjusting the pH of the mixture to 10, the stirring rod was finally rotated in the opposite direction once or twice to stop the flow of the reaction solution, and then the reaction solution was allowed to stand without substantially stirring. The reduction (precipitation) reaction was performed while maintaining the state (stirring speed: 0 rpm). As a result, many bubbles were generated in the liquid, and many of them remained without being broken at the liquid surface, and a stable foam layer was formed on the upper surface of the reaction liquid.

  Thereafter, the foam layer was separated from the liquid at the time when 10 minutes passed, and washed with water on a filter paper to obtain a solid content. This solid content was again washed with water on the filter paper, and then washed with stirring in pure water (20 minutes) − A linear nickel powder was produced through each step of stirring washing (30 minutes) -filtering-vacuum drying (23 ± 1 ° C.) while irradiating ultrasonic waves in ethanol.

2. Binding reaction of fluorescent substance 0.8 g of the linear nickel powder produced in 1 above was dispersed in 60 ml of diethylene glycol mono-n-butyl ether (BCA), stirred for 10 minutes, and then linear nickel using a magnet. The powder was allowed to settle, and about 50 ml of the fine BCA solution was removed to prepare a linear nickel powder solution 1. Separately, a solution 2 in which 0.1 g of dansyl chloride was dissolved in 50 ml of BCA was prepared.

  Next, 0.4 g of silane coupling agent KBM903 (γ-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise to Solution 2 while stirring at room temperature. The mixture was stirred for 10 minutes to mix the dansyl chloride solution and the silane coupling agent (solution 3). Next, the solution 1 and the solution 3 were kept warm in a 100 ° C. warm bath layer until the solution was warmed. After the solutions 1 and 3 reached 80 ° C. or higher, the solution 1 was added to the solution 3 at a stretch while stirring. Thereafter, the reaction was continued at 100 ° C. for 300 minutes. After 300 minutes, the reaction solution was removed from the hot tub and allowed to stand at room temperature for 60 minutes. Next, a magnet was placed at the bottom of the container containing the reaction solution to precipitate linear nickel powder, and then the supernatant was removed. Next, the remaining linear nickel powder is dispersed in 100 ml of BCA, stirred (10 minutes), settling using a magnet, and the removal of the supernatant liquid is repeated twice to remove excess fluorescent material and silane. The coupling agent was removed.

  Thereafter, the BCA solution containing the linear nickel powder was transferred onto a membrane filter, washed with BCA to obtain a solid content, and then dried with a vacuum dryer. Drying was performed at 100 ° C. all day and night to obtain a phosphor-bound nickel powder.

3. Preparation of anisotropic conductive film Bisphenol A type solid epoxy resin [manufactured by Japan Epoxy Resin Co., Ltd., trade names: Epicoat 1256 (referred to as Resin A), Epicoat 1002 (referred to as Resin B)], and bisphenol A type liquid Epoxy resin [made by Japan Epoxy Resin Co., Ltd., trade name: Epicoat 828US (referred to as Resin C)], microcapsule type imidazole curing agent [produced by Asahi Kasei Chemicals Corporation, trade name Novacure HX3941 (referred to as hardener) Were used at a ratio of resin A / resin B / resin C / curing agent = 40/20/40/35 by weight ratio. These materials were dissolved in butyl acetate to prepare a resin solution having a resin component, that is, a total concentration of three components of resin A, resin B, resin C, and a curing agent, of 40% by weight.

  Next, the phosphor-bound nickel powder obtained in 2 above is blended with this resin solution so that the metal filling rate represented by the ratio of the resin content and the total amount of metal powder is 0.5% by volume. The composite material for anisotropic conductive films was prepared by stirring and uniformly dispersing using a centrifugal stirring mixer. And after apply | coating this composite material on the PET film which performed the mold release process using a doctor knife, it is made to dry and solidify at 60 degreeC for 30 minutes, applying a magnetic field of 100 mT, and fluorescent substance binding nickel powder is obtained. An anisotropic conductive film having a thickness of 25 μm, which was fixed in a state of being oriented in the thickness direction of the film, was prepared.

4). Mounted product An IC chip in which 726 gold-plated electrodes with a width of 15 μm, a length of 100 μm, and a height of 16 μm are arranged at intervals of 15 μm, and an ITO chip with a width of 20 μm, a length of 100 μm, and a height of 0.15 μm at an interval of 10 μm And the same number of glass substrates formed. The anisotropic conductive film prepared in 4 above was placed on this glass substrate, and was temporarily bonded by applying pressure at 4 MPa for 2 seconds while heating to 50 ° C. Thereafter, the PET film subjected to the release treatment is peeled off from the anisotropic conductive film, and the IC chip is placed on the anisotropic conductive film while aligning the ITO electrode and the gold plating electrode, and heated to 180 ° C. However, it was pressurized and bonded for 30 seconds at a pressure of 20 gf per electrode to obtain a mounted product on which an IC chip and a glass substrate were mounted.

5. Inspection of mounted products The mounted products obtained above are inspected. Mirror unit U using a fluorescent microscope (Olympus, trade name: epi-illumination fluorescent system BX51), using a mercury lamp as an excitation light source, EX330-385 as an excitation filter, DM400 as a dichroic mirror, and BA420 as an absorption filter -Use MWU2. Thereby, ultraviolet light having a wavelength of 330 to 380 nm is irradiated as excitation light on the glass substrate side surface of the mounted product, and fluorescence emitted from the mounted product having a wavelength of 400 nm or more is detected.

  Using the above apparatus, a mounted product mounted with an anisotropic conductive film is observed. Further, as a comparative example, observation is also made with transmitted light in the visible region. The results are schematically shown in FIGS. 2 (a) and 2 (b). When the excitation light is irradiated and the fluorescence emitted from the fluorescent material is observed as in the present invention, the conductive particles 21 can be observed as shown in FIG. On the other hand, when observed with visible light, it looks as shown in FIG. In FIG. 2B, many points that look like conductive particles at first glance are observed compared to FIG. 2A. This observation point includes irregularities, dust, and the like 22, and conductive particles 21. In this way, when observed with light in the visible region, points other than the conductive particles are observed. Therefore, even if the conductive particles are not actually present, the result is as if they are present. You may get inspection information.

  The observed image is taken with a digital camera as shown in FIG. 2A, and the digital data is taken into a computer. The existence coordinates of the conductive particles are calculated from the data. Then, the electrode area 31 prepared in advance is overlaid with the layout diagram (FIG. 3) of the mounted product on which the electrode area 31 is described. This is shown in FIG. Conductive particle coordinate positions 41 exist on all the electrodes, and this mounted product is determined to be “good”.

  When the above determination is made to be performed by the computer, an area surrounded by four points (X1, Y1)-(X2, Y2)-(X3, Y3)-(X4, Y4) corresponding to the four corners of the electrode in the plane coordinates. An algorithm for determining whether or not conductive particle coordinates (x, y) exist is incorporated therein. For example, if one or more conductive particle coordinates exist in each electrode region, it is determined as “good”, and if there is even one electrode region whose conductive particle coordinate number is “0”, it is determined as “No”.

  ADVANTAGE OF THE INVENTION According to this invention, the electroconductive particle which exists between the electrodes which oppose the mounted goods mounted using the anisotropic conductive film can be test | inspected nondestructively. As a result, in-situ inspection of the actual product is possible instead of sampling inspection, and the reliability of the inspection result is improved. In addition, the inspection process can be made more efficient. The present invention can be suitably used in the field of electronics, particularly in the inspection process of a semiconductor package mounted product on a glass substrate or a flexible printed wiring board mounted product on a glass substrate.

The schematic diagram of the inspection method and apparatus of the mounted goods which are this invention. It is the figure which represented typically the result of having observed the mounting goods. (A) When observed by the method of the present invention. (B) When observed with transmitted light in the visible region. Mounted product layout The figure which displayed the electrode arrangement | positioning figure of the mounting goods, and the presence coordinate point of electroconductive particle in an overlapping manner.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 Excitation light source, 12 Compound light, 13 Excitation filter, 14 Excitation light, 15 Dichroic mirror, 16 Objective lens, 17 Mounted product, 18 Fluorescence, 19 Absorption filter, 100 Microscope, 101 Computer, 21 Conductive particle, 22 Concavity and convexity and dust Etc., 31 electrode region, 41 conductive particle coordinate position

Claims (5)

A mounted product inspection method for determining the quality of a mounted product by inspecting the presence position of the conductive particles of a mounted product mounted with an anisotropic conductive film containing conductive particles, wherein the conductive particles are A fluorescent substance is bonded to the surface directly or via an organic compound, and the surface of the mounted product is irradiated with excitation light, and the fluorescence emitted from the fluorescent substance is detected, and between the electrodes facing each other in the mounted product A method for inspecting a mounted product, wherein the presence or absence of conductive particles is confirmed .   2. The mounted product inspection method according to claim 1, wherein fluorescence emitted from the fluorescent material is detected using a fluorescence microscope. Conductive particles mounted article mounting the anisotropic conductive film including, a mounting article of the inspection apparatus for determining the quality of the mounting parts by examining the location of the conductive particles, conductive particles A fluorescent substance is bound to the surface directly or via an organic compound, means for irradiating the surface of the mounting product with excitation light, means for detecting fluorescence emitted from the fluorescent substance, and opposing electrodes in the mounting product An inspection apparatus for mounted products, comprising: means for confirming the presence or absence of conductive particles in between . 4. The inspection device for a mounted product according to claim 3, wherein the means for confirming the presence / absence of conductive particles between electrodes facing each other in the mounted product has means for calculating position coordinate data of the detected fluorescence. Inspected equipment for mounted products.   5. The mounted product inspection apparatus according to claim 4, further comprising means for determining whether the mounted product is good or bad using the position coordinate data.

Images