WO2005096003A1 - A method of testing the defect of a display panel - Google Patents

Abstract

A conductive adhesive combination is produced by mixing two kinds of curing compound. The adhesive combination makes it possible to fix a display panel on a chip temporarily in order to test its defect. If any defect is found, the semi-manufactured goods can be repaired or reprocessed easily. If no defect is found, the display panel can thus be fixed on the chip permanently.

Description

 TECHNICAL FIELD

 The present invention relates to a method for inspecting defects in a display panel, and in particular, to a method for inspecting defects in a liquid crystal display panel using a conductive adhesive having two different curing components. Background technique

 In the field of thin film transistor liquid crystal displays (TFT-LCD), a panel (generally a glass panel) of a liquid crystal display is bonded to a driving element or the like. Anisotropic Conductive Film (ACF) and anisotropic conductivity are generally used An adhesive (Anisotropic Conductive Adhesive, ACA) etc. electrically fixes and conducts electricity between two electrodes. These conventional anisotropic conductive materials mainly include a binder of a polymer substrate and conductive particles uniformly dispersed in the binder. Due to the electrical conductivity of this anisotropic conductive material, it is widely used for bonding TFT-LCD glass panels to drive circuit elements, such as Tape Automated Bonding (TAB), Chip on Film, COF), Chip on Glass (COG), Outer Lead Bonding (OLB) bonding technology.

For these traditional anisotropic conductive films or adhesives, in order to meet the requirements of high reliability, thermosetting polymers are mainly selected as the base to achieve high adhesion. For example, the use of polyester, epoxy resin, silicone resin, urethane resin, etc. can be subjected to condensation or cross-linking reaction after high temperature, pressure or catalysis, resulting in a three-dimensional network structure, corrosion, moisture attack, etc. Good resistance and suitable mechanical strength. However, due to its three-dimensional network cross-linked structure, it hardly reacts with any solvents or reagents. Therefore, it is not easy to perform a re-processing process in the joint application project of the TFT-LCD glass panel and the driving element. Especially in the COG process, because the driving element is the bare wafer directly bonded to the glass substrate, the bare wafer is often damaged and left on the glass substrate during reprocessing, or the anisotropic conductive material is left on the glass substrate and cannot be effectively removed. , Resulting in scrapped glass panels Missed. The larger the size of the glass panel, the greater the loss due to failed reprocessing.

 The process of bonding and inspecting a TFT-LCD glass panel with a driving element using a thermosetting conventional anisotropic conductive film is shown in Figure 1. First, an anisotropic conductive film is added to adhere the electrodes of the liquid crystal display panel and the driving circuit element (step 100). After that, a heating step (step 101) is performed so that the thermosetting material in the anisotropic conductive film can be permanently cured to fix the liquid crystal display panel and the driving circuit. An ultraviolet light sealing agent is coated on the liquid crystal display panel (step 102) and exposed to ultraviolet light (step 103) to cure the ultraviolet light sealing agent. Then, perform an inspection step (step 104) to inspect the liquid crystal display panel and the driving circuit components for defects. If there are no missing items, proceed directly to the next step (step 106). However, if any defects are found on the panel, the panel is discarded directly (step 105).

 On the other hand, for the purpose of repairability, another thermoplastic polymer is selected as the base agent to achieve the purpose of temporary bonding. For example, polyethylene, polyvinyl chloride, polymethyl methacrylate, polyimide, and other resins exhibit plasticity at high temperatures. Therefore: ¾ In the joint application project of TFT-LCD glass panel and driving element, when the inspection process finds defects due to element alignment or poor bonding, driving element defects, etc., it can use the high temperature for re-processing. Eliminate driving elements and anisotropic conductive materials to avoid scrapping expensive glass panels. However, such high-temperature plasticity behavior of thermoplastic resins may affect the reliability of the product in high-temperature environments encountered in subsequent use.

In order to meet the goals of reliability and reworkability at the same time, attempts have been made to mix thermosetting polymers and thermoplastic polymers in different proportions as the above-mentioned discretionary adhesives. For example, refer to the technical report CP7652K applying anisotropic conductive films to COG ( Sony Chemical Corporation), UV-curable coatings for electronic components (IEEE Process-Part A for Component Packaging and Manufacturing Technology, Volume 17, Issue 3, September 1994), Polymer Engineering Theory (Oxford, Oxford, UK) University Press, 1987), and Basic Theory of Polymer Materials (New York; Wiley and Sons Publishing Company, 1982). These thermoplastic and thermosetting polymer-based adhesives did not achieve the required reliability and reworkability as expected in actual use The purpose of the invention

 In view of the problems and disadvantages generated by the conventional defect inspection method in the prior art mentioned above, the main purpose of the present invention is to provide two fixing methods, so that it is easier to repair or reprocess after the f inspection step. Way to proceed. These two types of fixing methods have different curing methods, one of which is thermal curing and the other is exposure to H.

 Another object of the present invention is to provide a new conductive adhesive, which can fix objects in different curing modes.

 It is a further object of the present invention to eliminate the problematic panel from having to be discarded after a defect is discovered.

 Yet another object of the present invention is to improve the yield of products through a convenient repair or reprocessing process.

 According to the above-mentioned object, the present invention provides a method for inspecting a display panel, comprising the steps of temporarily fixing the display panel and a driving circuit element in a pet, inspecting the defects of the display panel, and permanently fixing the display panel and Drive circuit elements. After a defect is found in the inspection step, a step of repairing the display panel is performed. The display panel in the invention can be a liquid crystal display panel or a plasma display panel.

 The temporary fixing can be achieved by heating a conductive adhesive located between the display panel and the wafer, wherein the conductive adhesive includes a thermosetting resin, a photocurable polymer, a photoinitiator, and conductive particles. Permanent fixation can be achieved by a conductive adhesive between the illuminated display panel and the wafer. BRIEF DESCRIPTION OF THE DRAWINGS

 FIG. 1 is a flowchart of combining a liquid crystal display with a driving circuit element in a conventional manner;

FIG. 2 is a method according to the present invention using two different fixed steps Flowchart of simple repair or rework of the display panel; and

 FIG. 3 is a flowchart of a method for fixing a liquid crystal display panel and a driving circuit element using a conductive adhesive according to the method of the present invention. detailed description

 Preferred embodiments of the present invention are described in detail below. However, in addition to these detailed descriptions, the present invention can be widely implemented in other ways. The scope of the present invention is not limited by the following specific embodiments, but the scope of the appended claims shall prevail.

 The invention provides a method for inspecting a display panel, which includes the steps of temporarily fixing the display panel and a driving circuit element, inspecting defects of the display panel, and permanently fixing the display panel and the driving circuit element. After a defect is found in the inspection step, a step of repairing the display panel is performed. The display panel may be a liquid crystal display panel or a plasma display panel in the present invention. "

 Temporary fixing can be achieved by heating a conductive adhesive located between the display panel and the wafer. The conductive adhesive includes a thermosetting resin, a photocurable polymer, a photoinitiator, and conductive particles. Permanent fixing can be achieved by irradiating a conductive adhesive located between the display panel and the wafer. The weight ratio of the above-mentioned thermosetting resin to photo-curable polymer is 50:50 to 90:10, and the above-mentioned photoinitiator accounts for 0.1 to 5% by weight of the composition. The conductive particles are uniformly dispersed in the binder, and may be conductive metal particles or plastic particles with metal deposited on the surface.

The above-mentioned thermosetting resin may be polyester, epoxide, silicone resin or urethane resin. The photo-curable polymer may be an ultraviolet (W) curable polymer, an electron beam (EB) curable polymer, an infrared (IR) curable polymer, or a visible light (VL) curable polymer. The aforementioned photo-curable polymers may be epoxy resins, bisphenol resins, unsaturated polyesters, and acrylate resins. Examples include urethane diacrylates and epoxy diacrylates. The photoinitiator may be a benzoin monomethyl ether, a higher fluorenyl benzoin ether, benzophenone, etc. The type of the photoinitiator may be fixed according to the light used. Depending on the type of polymer.

 As for the visible light (VL) curable polymer, it may be a combination of non-aromatic amines such as N, N-dimethylaminoethyl methacrylate and ketones or dimers that can absorb visible light in the 400-500 nm range.

 In the conductive adhesive composition used in the method of the present invention, the thermosetting resin is used to provide the bonding strength to maintain the temporary bonding of the driving element and the glass panel for subsequent inspection procedures. Therefore, its weight should account for the 50 to 90% by weight of the total weight of the photocurable polymer. Based on the need for reworkability, photocurable polymers are preferred! ^ The total weight of the thermosetting resin and the photo-curable polymer is more than 10% by weight but not more than 50% by weight. The higher the proportion of the thermosetting resin, the stronger the adhesive strength. However, when it is confirmed in the inspection procedure that due to poor alignment of the glass panel and the driving element electrodes, or poor COG connection, defective glass panel or defective driving element, it is necessary to perform heavy processing. .

 In the method for inspecting a liquid crystal display of the present invention, after the glass panel and the driving element are bonded with the conductive adhesive composition and temporarily bonded by heating, the combination of the obtained glass separation panel and the driving element will be described later. Sometimes called "semi-finished product".

 After the defect inspection step, the display panel and the wafer are sealed with a photo-curable seal. The sealing step includes applying or coating a light-curable sealant to the display panel and the wafer, and then irradiating the light-curable sealant with light. The photocurable sealant may be epoxy-based lipid, bisphenol resin, unsaturated polyester or acrylate resin. One preferred method is that the photocurable sealer is selected the same as the photocurable polymer in the conductive adhesive, so that the sealing step and the permanent fixing step can be combined together or performed in the same step. The ultraviolet light curable sealant may be epoxy resin, bisphenol resin, unsaturated polyester or acrylate resin.

In the method for inspecting a liquid crystal display of the present invention, the inspection program includes two procedures of an optical instrument inspection and an electrical inspection. The optical instrument inspection is used to check the alignment and adhesion of the panel and components, while the electrical inspection is sent by the test control system to confirm the Whether the assembly of the fixing panel and the driving element is defective.

 The term "defect" as used herein means any quality control tester in a liquid crystal display that cannot pass the liquid crystal display device, including the optical instruments and electrical tests described above. These defects include, for example, poor alignment or bonding between the panel and the driving element, poor electrical connection, defects in the manufacture of the panel, or defects in the manufacturing of the driving element, or any defects that cause poor quality when the liquid crystal display element is driven, etc. .

 For example, when the panel and components are found to be misaligned or bonded to each other by optical instrument inspection, the panel and the drive components are peeled off and the panel and components are rechecked to see if they are still usable. If it is still usable, the conductive adhesive of the present invention is used again to adhere to other components.

 During the electrical inspection, a test screen is sent by the test control system, and the sent screen can detect whether the test panel and the driving element themselves are defective. If the panel or the driving element is found to be defective from the test picture, check whether the panel or the driving element can be repaired, and if it can be repaired, perform laser repair and then send it to the downstream process. If it cannot be repaired, remove it and check if other components are still available. If it is still usable, the conductive adhesive of the present invention is used again for adhesion to other components. Scrap if it cannot be repaired.

 These optical instruments and electrical inspections are inspection methods well known to those skilled in the art, and therefore will not be described in further detail.

 The conductive adhesive composition used in the method for inspecting a liquid crystal display of the present invention can be formulated into a liquid and applied through a syringe or the like, or can be prepared in a dry film state and used in the form of an adhesive tape.

The flowchart of the inspection method of the present invention is shown in FIG. 2. First, a display panel may be provided, which may be a liquid crystal display panel or other such as a plasma display panel, and is temporarily fixed to a wafer (step 10), where the wafer is usually a driving circuit element. By using a mixed adhesive, wherein the mixed adhesive includes a thermosetting resin and a photo-curable polymer, a temporary fixing step may be performed after the thermosetting resin is heated. Then, the display panel can be directly inspected for defects (step 12). If the display panel or driver circuit element Defects found in parts can be easily repaired or reprocessed (steps

14), because the panel and the drive circuit components are only temporarily fixed. If no defects are detected in the display panel or the driver circuit components, perform a permanent fixation step (step 16) to expose the photocurable polymer in the hybrid adhesive to light of the corresponding wavelength.

 A flowchart of another inspection method of the present invention is shown in FIG. 3. When the inspection step is started (step 20), a conductive adhesive is applied to the display panel or the driving circuit element. The conductive adhesive may be a mixture including a thermosetting resin and a photo-curable polymer, and conductive particles. The conductive particles are uniformly distributed in the conductive adhesive. In addition, a photoinitiator may be added to the conductive adhesive, and initiated when light of a corresponding wavelength is irradiated to the conductive adhesive.

 Then, the conductive adhesive is heated (step 22) to temporarily fix the display panel and the driving circuit components, because the thermosetting resin is cured due to the heating. You can then inspect the display panel directly for defects (step 24). If there are no defects in the display panel and the drive circuit components, the panel needs to be sealed by adding a sealant (step 28). Sealers are photocurable and can be cured by exposure. When irradiated with a corresponding wavelength, the sealant is cured. The photocurable sealant may be the same as the main component of the photocurable polymer. Therefore, the step of illuminating can be omitted or incorporated into a subsequent fixed step.

 Next, the conductive adhesive in the panel is irradiated with light of a corresponding wavelength to permanently fix the driving circuit element (step 30). If the composition of the sealing agent is the same as that of the photocurable polymer, the sealing step can be completed at the same time. After the panel and drive circuit components are inspected and fixed, they will be sent to the next process.

The main advantage of the present invention is to provide two fixing methods to make it easier to repair or reprocess after the inspection step. These two fixing methods have different curing methods, one of which is thermal curing and the other is curing by exposure. In addition, the invention also provides a new conductive adhesive, which can fix the object through two different curing methods. After a defect is found, the panel in question need not be discarded in the present invention. In addition, the present invention improves the qualification rate of the product through a convenient repair or reprocessing process.

 For those skilled in the art, although the present invention has been described with the preferred embodiments described above, they are not intended to limit the spirit of the present invention. Modifications and similar arrangements made without departing from the spirit and scope of the invention should be included within the scope of the following claims, and such scope should be consistent with the broadest interpretation covering all modifications and similar structures. Therefore, the preferred embodiments of the present invention as explained above can be used to identify various changes made without departing from the spirit and scope of the present invention.

Claims

Rights request 1. A method for inspecting a liquid crystal display panel, comprising the following steps:  Temporarily fixing the liquid crystal display panel and a driving circuit element;  Inspecting the liquid crystal display panel for defects; and  The liquid crystal display panel and the driving circuit element are permanently fixed. 2. The method for inspecting a liquid crystal display panel according to claim .1, further comprising a step of repairing the liquid crystal display panel after a defect is found in the inspection step. 3. A method for inspecting a display panel, comprising:  Heating a conductive adhesive to temporarily fix the display panel and a wafer, wherein the conductive adhesive includes a thermosetting resin, a photocurable polymer, a photoinitiator, and conductive particles; and  Inspect the display panel for defects. 4. The method of inspecting a display panel according to claim 3, further comprising the step of repairing said defects after a defect is found in the inspection step. The method of inspecting a display panel according to claim 4, further comprising the step of sealing said display panel and said wafer. 6. The method of inspecting a display panel according to claim 5, further comprising the step of irradiating the conductive adhesive to permanently fix the display panel and the wafer. The method of inspecting a display panel according to claim 3, further comprising the step of applying a photo-curable sealant to the display panel and the wafer. 8. The method for inspecting a display panel according to claim 7, wherein the curable sealant is selected from the group consisting of an ultraviolet light curable sealant, an electron beam light curable sealant J, and an infrared light curable sealant. , And visible light curable sealant. The method for inspecting a display panel according to claim 8, wherein said external light curable sealant is selected from the group consisting of epoxy resins, bisphenol resins, unsaturated polyesters and J¾acrylate resins. 10. The method of inspecting a display panel according to claim 9, further comprising the step of irradiating the photocurable sealant with light. 11. The method of inspecting a display panel according to claim 7, further comprising the step of radiating the conductive adhesive with light J2 to permanently fix the display panel and the wafer. 12. The method of inspecting a display panel according to claim 3, wherein: the inspecting step includes an optical instrument inspecting step. 13. The method of inspecting a display panel according to claim 12, wherein said discretionary inspection step includes an electronic instrument inspection step. The method of inspecting a display panel according to claim 3, wherein a weight ratio of said solid resin to said photocurable polymer is 50:50 to 90:10. 15. The method for inspecting a display panel according to claim 14, wherein said discretionary photoinitiator accounts for 0.1 to 5% by weight of the composition. 16. The method for inspecting a display panel according to claim 3, wherein said thermosetting resin is selected from the group consisting of polyester, epoxide, silicone resin and urethane resin. 17. The method of inspecting a display panel according to claim 16, wherein the photocurable polymer is selected from the group consisting of an ultraviolet curable polymer, an electron beam curable polymer, an infrared curable polymer, and a visible light curable polymer. . 18. The method of inspecting a display panel according to claim 17, wherein the photocurable polymer is an ultraviolet curable polymer selected from the group consisting of epoxy resins, bisphenol resins, unsaturated polyesters, and acrylate resins. Thing. 19. A method for inspecting a defect of a liquid crystal display panel, comprising:  The liquid crystal display panel and the wafer are temporarily fixed by heating a conductive adhesive positioned between the liquid crystal display panel and a wafer, wherein the conductive adhesive includes a thermosetting resin, a photo-curable polymer, a light Initiator, and conductive particles;  Inspect the liquid crystal display panel for defects;  Sealing the liquid crystal display panel and the chip; and  The liquid crystal display panel and the wafer are permanently fixed by irradiating the conductive adhesive.