JP2006165458A - Method for sticking thin plate to plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To apply adhesives to a plurality of positions flatly and economically. <P>SOLUTION: This sticking method comprises a step (step 55) for arranging a plane having an adhering surface to which an object to be stuck is stuck so that the adhering surface becomes an upper surface; an application step (step 56) for applying an adhesive to each adhering surface of the arranged plane; a step (step 57) including a semi-curing step for increasing the viscous coefficient of the applied adhesive, and a flattening step to flatten the surface by removing at least partially the surface of the adhesive whose viscous coefficient has been increased; and a step (step 58) including a step for sticking fast the object to be stuck to the flattened surface of the adhesive, and a step for curing the adhesive. The flattening step comprises a step for exposing at least a part of the adhesive to the surface of a first net and a step for removing the adhesive exposed to the upper part of the first net by sliding a squeegee on the surface of the first net. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for adhering a thin plate to a flat plate, and more particularly to a method for adhering a chip body to a reinforcing plate in a step of manufacturing a non-contact IC card.

  Non-contact IC cards are used in various fields, mainly for applications such as railway ticket gates, and are expected to be applied in many fields in the future. The non-contact IC card is configured by sandwiching a communication antenna and a semiconductor chip (IC chip) between predetermined sheets. An IC chip is configured such that a chip body in which a laminated film constituting a circuit is formed on a substrate such as silicon is supported by a reinforcing plate usually made of stainless steel. The reinforcing plate protects the chip body so that the chip body is not excessively deformed, and has a function as a heat sink that absorbs heat generated from the chip body.

  Various IC chip manufacturing methods have been proposed. As one of them, first, the back surface of a wafer on which a large number of chip bodies are formed is thinned, and then the thinned wafer is cut. There is a method of manufacturing an IC chip by separating each chip body and then bonding the separated chip body to a reinforcing plate.

  Specifically, the step of adhering the separated chip body to the reinforcing plate is performed by the following procedure using a screen printing technique. First, the plurality of reinforcing plates are fixed on the base with the surface to which the adhesive is applied facing up. Next, an opening is provided on the portion corresponding to the reinforcing plate, and the other portion is covered with a closed mask. Next, an appropriate adhesive is applied from above the mask, a squeegee is moved on the mask, and the adhesive is stretched to flow from the opening. As a result, the adhesive is uniformly applied to the reinforcing plate via the opening (see Patent Document 1). The adhesive is not applied to the blocked portion. Next, the mask is removed, and the chip body is brought into close contact with the adhesive application surface. If the adhesive is a high-temperature curable resin, the adhesive is cured by heating at this temperature for a predetermined time in this state (for example, if it is an epoxy resin, it is heated at 120 ° C. for 2 hours). Bonded to the reinforcing plate. If the adhesive is an ultraviolet curable resin, it may be cured by irradiating with ultraviolet rays instead of heating.

  Cover the opening with a mesh-like sheet, feed the elastomer from the top of the sheet, and push it in as if it is stretched with a squeegee. Or tilting (see Patent Document 2). Moreover, although it is not the application | coating method of an adhesive agent, there also exists a method of removing the liquid pool which arises in the peripheral part of a coating agent with a spatula, and ensuring flatness (refer patent document 3).

In addition to the screen printing technique, a spin coating method, which is a typical method for forming a thin film in the semiconductor field, may be used for applying the adhesive.
JP 9-321067 A JP-A-11-74289 JP 2004-50108 A

  However, the prior art has the following problems. That is, a high-temperature curable resin frequently used as an adhesive for IC chips has a property that the solvent evaporates with time or by heating and is gradually cured. For this reason, since the amount of the solvent is large for a while after application, the fluidity is high, and the viscosity is low, the peripheral portion of the adhesive application surface rises like a bank due to surface tension, and the flatness deteriorates. If the IC chip is placed on the adhesive in this state, the adhesive has high fluidity and the IC chip moves, so that the IC chip may not be accurately aligned. This means that the IC chip is not fixed at the correct position on the reinforcing plate. Moreover, since the fluidity of the adhesive is high, it is also conceivable that the adhesive wraps around the front side of the IC chip. These phenomena may seriously affect the quality of the IC chip. This problem cannot be solved even if an adhesive is applied from above the mesh-like sheet, in the case of a material with high fluidity, deformation occurs as soon as the sheet is removed.

  Therefore, it can be considered that the IC chip is brought into close contact with the adhesive in a state where the adhesive is cured to some extent and the fluidity is reduced. However, at this point, the adhesive is in a semi-cured state with poor flatness, so the adhesive does not go well to the IC chip's adhesive surface, causing poor adhesion or fixing in an inclined state. There is a possibility of being. These phenomena can also have a significant impact on the quality of the IC chip. In order to avoid this problem, it may be possible to recover the flatness by scraping the deteriorated flatness of the semi-cured adhesive with a squeegee. In other words, it is in a state that trees are standing, so it is extremely difficult to flatten the whole surface even if the surface is rubbed with a squeegee in order. Although it is not impossible to flatten each coated surface by individually rubbing each reinforcing plate, it is problematic in terms of work efficiency.

  In addition, the thickness of the wafer affects the thickness of the non-contact IC card, which is the final product, and the wafer is becoming increasingly thinner in recent years, with the objective of ensuring flexibility against bending that occurs during use of the non-contact IC card. Tend to. For this reason, it is necessary to reduce the film thickness of the adhesive accordingly, but in the prior art, it is the limit to form a film thickness of about 50 μm (see Patent Document 1), and the accuracy is also high. It was not expensive.

  Note that coating methods other than screen printing, such as spin coating, are excellent in terms of film thickness control, but require a dedicated and expensive apparatus and may not be practical in terms of cost.

  The present invention has been made in view of such problems, and provides a method for applying an adhesive to a plurality of reinforcing plates flatly and economically when bonding an IC chip to a substrate. Objective. The present invention more generally aims to provide a method for applying an adhesive to a plurality of positions in a flat and economical manner.

  In order to solve the above-described problem, the bonding method of the present invention includes a step of arranging a flat plate having an adhesive surface to which an adherend is bonded, with the adhesive surface as an upper surface, and an adhesive on each of the adhesive surfaces of the arranged flat plate. An application step for applying a coating; a semi-curing step for increasing the viscosity coefficient of the applied adhesive; and a planarization step for flattening the surface by removing at least a portion of the surface of the adhesive having an increased viscosity coefficient. And a step of closely attaching the adherend to the flattened surface of the adhesive, and a step of curing the adhesive thereafter. Here, the planarization step is a first mask having a first opening, and the first opening is covered with a first net provided on the substantially same surface as the upper surface of the first mask. The first mask is attached to the flat plate at a position where the first opening is above the bonding surface and at least a part of the first net bites into the adhesive, and at least a part of the adhesive is attached. Exposing on the first net and sliding the squeegee over the surface of the first net to remove the adhesive exposed above the first net.

  When an adhesive is applied to each adhesive surface of the flat plate, when the viscosity coefficient of the adhesive is small, the applied surface of the adhesive is deformed by surface tension. However, after the adhesive is semi-cured in that state and a shape retention force is generated, a part or all of the surface of the adhesive is removed by the first net and the squeegee, so that only unnecessary portions are efficiently used. Can be removed. In addition, since sufficient adhesive strength remains at this point, it is possible to obtain a sufficient adhesive force by bringing the adherend into close contact with the adhesive and then curing the adhesive.

  Further, the application step includes a step of attaching a second mask having a second opening to a flat plate at a position where the opening is above the bonding surface, a step of supplying an adhesive on the second mask, And a step of sliding the squeegee on the surface of the second mask to move the adhesive from the second opening to the adhesive surface, and applying the adhesive to the adhesive surface.

  Further, a plurality of flat plates may be arranged, and the first opening of the first mask and the second opening of the second mask may be provided at positions corresponding to the respective flat plates.

  An epoxy resin may be used as the adhesive, and the semi-curing step may increase the viscosity coefficient to at least 30000 mPa · s or more.

  Further, an ultraviolet curable resin may be used as the adhesive, and the semi-curing step may be performed by irradiating with ultraviolet rays to increase the viscosity coefficient to at least 30000 mPa · s or more.

  The roughness of the first net is desirably in the range of 100 to 600.

  An IC chip manufacturing method of the present invention is an IC chip manufacturing method in which one surface of a chip body is bonded to a reinforcing plate, and a step of manufacturing a plurality of chip bodies and a plurality of reinforcing plates are manufactured. A step, a step of fixing a plurality of reinforcing plates to the base with an adhesive surface of the reinforcing plate as an upper surface, a chip body as an adherend, a reinforcing plate as a flat plate, and using any one of the bonding methods described above Bonding the chip body to the reinforcing plate.

  In this case, the thickness of the IC chip can be 75 μm or less, and the thickness after the adhesive flattening step can be 50 μm or less.

  As described above, according to the bonding method of the present invention, when the IC chip is bonded to the substrate, the adhesive applied to a plurality of locations is made into a semi-cured state, and then the method is simple and highly accurate. Unnecessary portions can be removed together to ensure the flatness of the coated surface. For this reason, an adhesive agent can be apply | coated to a some reinforcement board flatly and economically.

  Hereinafter, the bonding method of the present invention will be described with reference to the flowchart shown in FIG. 1 by taking a non-contact IC card manufacturing method as an example.

  (Step 51) First, a wafer W having a large number of chip bodies C formed on a silicon substrate K is manufactured. Next, an acceptance inspection of the wafer W is performed as necessary, and defective wafers W are selected. FIG. 2 shows a plan view of the wafer. The chip body C is formed on a circular silicon substrate K in a two-dimensional alignment. The dimension per chip body C is, for example, about 4 mm × 5 mm. In addition to silicon, gallium arsenide and other materials generally used as wafer materials can be used as the substrate.

  (Step 52) Next, the back surface of the surface of the wafer W on which the chip body C is formed is polished. The wafer W has a thickness of about 0.65 mm in one example. For example, the thickness is reduced to some extent by, for example, mechanical polishing, and finally finished by chemical etching to 0.1 mm or less. In one example, about 0.075 mm. Thinning to:

  (Step 53) Next, a processing tape (not shown) is attached to the wafer W. The processing tape is obtained by, for example, applying a UV curable resin or a high temperature peelable resin to a plastic sheet. By using the processing tape, the cutting resistance can be suppressed, the movement of the wafer W and the grindstone at the time of cutting can be stabilized (vibration can be prevented), and chipping of the wafer W (breaking of the wafer along the cutting line) can be achieved. Can be prevented.

  (Step 54) Next, the processing tape is held on a fixture (not shown), and the wafer W is cut with a grindstone (not shown). As the grindstone, for example, a grindstone using artificial diamond as abrasive grains is used. As a result, the wafer W is separated into individual chip bodies C. Thereafter, the processing tape is peeled from the chip body C.

  (Step 55) Next, a reinforcing plate H made of stainless steel is prepared and mounted on the base 11. As described above, the reinforcing plate H has a function of protecting the chip body C and serving as a heat sink. 3 is a perspective view of the reinforcing plate mounted on the base, and FIG. 4 is a partially enlarged view of FIG. 3 (the base 11 is the lower side in any figure). The reinforcing plate H is a thin plate made of stainless steel. In one example, the planar size is about 5 mm × 6 mm, and the thickness is about 0.1 to 0.2 mm. A plurality of reinforcing plates H are fixed to the base 11 in a lattice shape with the adhesive surface H1 (see FIG. 4) with the chip body C as the upper surface. The reinforcing plate H and the base 11 can be fixed using appropriate means such as a double-sided adhesive tape.

  (Step 56) Next, an adhesive is applied to the reinforcing plate H. More specifically, this step is performed according to the following sub-steps.

  First, the second mask 12 having the second opening 13 is prepared. FIG. 3 shows a perspective view of the mask, and FIG. 4 shows a partially enlarged view of FIG. 3 (the second mask 12 is the upper side in any figure). The material of the 2nd mask 12 should just have the surface material which the adhesive agent S can move smoothly, and does not ask | require a kind, such as a steel plate and a plastic. The area and position of the second opening 13 coincide with the area and position of the bonding surface H1 of the reinforcing plate H held on the base 11. A second net 14 is provided on the upper surface of the second opening 13. Positioning is performed so that the position of the second opening 13 matches the position of all the corresponding bonding surfaces H1, the second mask 12 is lowered, and the second mask 12 is attached to the reinforcing plate H on the base 11. . As a result, the adhesive surface H1 communicates with the upper space of the second mask 12 through the second net 14 and the second opening 13, and the portion other than the adhesive surface H1 is covered with the second mask 12. .

  FIG. 5A is a cross-sectional view showing the positional relationship between the reinforcing plate H, the second mask 12 and the second opening 13. The thickness of the second mask 12 is formed so as to be approximately the same as the thickness of the adhesive S applied, and the second net 14 is disposed so as to be substantially flush with the upper surface of the second mask 12. . The application thickness of the adhesive S can also be controlled by adjusting the relative height between the second mask 12 and the reinforcing plate H while the second mask 12 is thickened.

  Next, as shown in FIG. 5B, an adhesive S is supplied onto the second mask 12. As the adhesive S, for example, a high temperature curable epoxy resin can be used. Next, as shown in FIG. 5C, the squeegee 15 is slid on the surfaces of the second mask 12 and the second net 14, and the adhesive S is moved from the second opening 13 to the second net 14. Then, the adhesive S is applied to the adhesive surface H1. If necessary, the squeegee 15 may be reciprocated as shown in FIG. Here, the second net 14 is provided in order to uniformly fill the inside of the second opening 13 with the adhesive S. Therefore, when the adhesive S has a small viscosity coefficient, it is not always necessary to use it.

  Finally, when the second mask 12 is removed, a state in which the adhesive S is applied on the adhesive surface H1 is obtained as shown in FIG.

  (Step 57) Next, the adhesive applied to the substrate is flattened. The adhesive S applied in the previous step has a certain viscosity coefficient, but is still in a state of high fluidity. Therefore, if left as it is, as shown in FIG. The outer peripheral part of the application surface of the agent S rises and the inside becomes lower. This step is performed according to the following sub-steps in order to remove the unevenness of the coated surface due to the fluidity of the adhesive S.

  First, as shown in FIG. 6 (a), the outer peripheral portion of the application surface of the adhesive S is left standing for a while. When the solvent contained in the adhesive S and ensuring the fluidity of the adhesive evaporates and the component ratio of the epoxy resin increases, the viscosity coefficient gradually increases and a semi-cured state is obtained. The time required for this is about 10 to 40 minutes at 80 ° C. If the temperature is lowered and the time is left as it is, the required time increases. If the temperature is raised, the required time is shortened, but the relationship between temperature and time can be arbitrarily selected. Here, the semi-cured state is an intermediate between the fluidized state and the cured state, the viscosity coefficient is smaller than that of the fluidized state, cannot move freely by surface tension or light vibration, and has shape retention force. However, for example, if it is rubbed with the squeegee 15, it is in a state of being easily deformed and separated. Adhesive strength remains sufficiently, and a normal adhesion state can be obtained by placing an adherend. In the case of an epoxy resin, the viscosity coefficient in the semi-cured state is in the range of about 30000 to 250,000 mPa · s. The fluid state is a state where the viscosity coefficient is small and the fluidity of the adhesive S is large, and can be freely deformed by surface tension or the like. The cured state is a state in which the fluidity of the adhesive S is almost lost and becomes a solid state.

Next, as shown in the upper side of FIG. 6A, the first mask 17 is set above the reinforcing plate H applied with the adhesive S and made into a semi-cured state. 7 is a perspective view of the first mask, and FIG. 8 is a partially enlarged view of FIG. 7 (the first mask 17 is the upper side in any figure). The material of the 1st mask 17 should just have the surface material which the adhesive agent S used as the semi-hardened state can move smoothly, and does not ask | require a kind, such as a steel plate and a plastic. The area and position of the first opening 18 coincide with the area and position of the bonding surface H1 of the reinforcing plate H held on the base 11. The first opening 18 is covered with a first net 19. The first net 19 is provided on substantially the same plane as the upper surface of the first mask 17. The first net 19 is made of plastic or stainless steel. The roughness of the net is generally # 100 to # 350 in the former and # 400 to # 600 in the latter, but is particularly preferably about # 250. The roughness of the net indicates how many eyes are in an area of 1 inch square. For example, # 250 means that there are about 250 eyes in 1 inch square.
Next, as shown in FIG. 6B, the first mask 17 is lowered to a height at which at least a part of the first net 19 bites into the adhesive S. As a result, at least a part of the adhesive S is exposed above the first net 19. FIG. 9 is an enlarged view of FIG. 6B, and shows the relationship between the first net 19 and the adhesive S at this time. Since the adhesive S is in a semi-cured state, it does not deform greatly even when it comes into contact with the first net 19, and the shape as it is is maintained. In other words, the bulging portion of the outer peripheral portion of the adhesive S is cut by the first net 19 and is exposed above the first net 19 in an almost intact state.

  Next, as shown in FIG. 6C, the adhesive S exposed on the first net 19 is removed by sliding the squeegee 15 on the surfaces of the first mask 17 and the first net 19. To do. Since the first net 19 is provided on substantially the same plane as the upper surface of the first mask 17, the squeegee 15 moves smoothly on the first net 19 and the first mask 17 without a step. And the excess adhesive S can be efficiently removed. If necessary, the squeegee 15 may be reciprocated as shown in FIG.

  Here, what is important is that the amount of the adhesive S exposed on the first net 19 can be adjusted by adjusting the mesh roughness of the first net 19. That is, if a coarse mesh is used, a large amount of the adhesive S is exposed to the outside of the first net 19, and if a fine mesh is used, the amount of the exposed adhesive S decreases, and the coating thickness of the adhesive S is subtle. Adjustments can be made. The coating thickness of the adhesive S can also be adjusted by adjusting the relative height of the first net 19 with respect to the adhesive S.

  Next, when the first mask 17 is removed, a flat adhesive S is obtained on the adhesive surface H1, as shown in FIG. 6 (e). In addition, the application | coating thickness of the adhesive agent S at this time can be 50 micrometers or less.

  (Step 58) Next, the chip body C is attached to the substrate H. Specifically, the surface opposite to the surface where the elements of the chip body C are formed (the surface on the substrate side of the wafer) is brought into close contact with the application surface of the adhesive S. Next, the whole is heated to cure the adhesive S. In the case of epoxy resin, the time required for curing is about 2 hours at 120 ° C. Thereafter, the reinforcing plate H is separated from the base 11. Through the above steps, the IC chip in which the reinforcing plate H is attached to the chip body C is completed.

  (Step 59) Thereafter, the IC chip is washed and an appearance inspection is performed. Further, the completed IC chip is mounted on the antenna substrate together with the communication antenna, a protective film that covers the IC chip and the communication antenna is formed on the antenna substrate, and the protective film and the antenna substrate are covered with an exterior sheet. A non-contact IC card is completed.

  The effects of the present invention are summarized as follows.

  First, when using a resin with high fluidity in the initial state when bonding the resin to the substrate, the flatness may deteriorate due to surface tension, but after applying the adhesive, the solvent of the adhesive is evaporated. After increasing the viscosity coefficient, excess portions can be removed using a net and squeegee. For this reason, a flat coating surface can be obtained irrespective of the viscosity coefficient (fluidity) of the resin.

  In addition, the amount of adhesive to be removed can be adjusted by adjusting the mesh roughness of the net, so that it is possible to obtain a coating thickness with the necessary and sufficient accuracy when bonding thin elements such as IC chips. Can do. The inventor of the present application has confirmed that the coating thickness can be adjusted in the order of 1 μm.

  Note that the bonding method of the present invention is not limited to the embodiment described above. For example, an ultraviolet curable resin can be used instead of an epoxy resin. Examples of the ultraviolet curable resin include 123S manufactured by Noland (used ultraviolet wavelength 254 nm), but any ordinary ultraviolet curable resin may be used. The specific procedure is the same as that of the above epoxy resin.

In one example, the above resin was applied to the reinforcing plate by screen printing in the same procedure as in Step 56, and then semi-cured by irradiating with ultraviolet rays having a wavelength of 360 nm. At this time, the total irradiation amount of ultraviolet rays was 450 mJ / cm ² . Next, the resin surface was flattened using the first net in the same procedure as in step 57. By sliding the squeegee on the first mask and the first net, the surface of the resin is flattened, and the cured film formed on the surface of the resin is broken, so that the internal uncured highly viscous resin Appears on the surface. Next, the chip body is brought into close contact with the adhesive in the same procedure as in step 58 and heated at 120 ° C. for 1 hour. Thereby, the chip body can be bonded to the reinforcing plate. In addition, when using said resin, the heating temperature for hardening should just be 65 degreeC or more at least. Thus, when using an ultraviolet curable resin, the same adhesion as when using an epoxy resin is possible by semi-curing with ultraviolet light and finally curing by heating.

  For example, when an adhesive having a high viscosity coefficient is used from the beginning, it is not necessary to make the adhesive semi-cured, and the adhesive may be flattened by the second mask immediately after application. Further, when an adhesive having a higher viscosity coefficient is used, it is sufficient to use a squeegee at the same time when applying the adhesive with the first mask.

  Furthermore, the present invention can be applied to the manufacture of a hybrid IC (stacked IC) in which ICs are bonded together.

It is a flowchart which shows the adhesion method of this invention. It is a top view of a wafer. It is a perspective view of the reinforcement board mounted in the base, and a 2nd mask. FIG. 4 is a partially enlarged view of a reinforcing plate and a second mask shown in FIG. 3. It is a step figure which shows the procedure which apply | coats an adhesive agent. It is a step figure which shows the procedure which planarizes an adhesive agent. It is a perspective view of the reinforcement board mounted in the base and a 1st mask. FIG. 8 is a partially enlarged view of the reinforcing plate and the first mask shown in FIG. 7. It is sectional drawing which shows the relationship between a 1st net | network and an adhesive agent in the step which planarizes an adhesive agent.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Base 12 2nd mask 13 2nd opening 14 2nd net 15 Squeegee 17 1st mask 18 1st opening 19 1st net C Chip body W Wafer H Reinforcement board H1 Adhesive surface S Adhesive

Claims (8)

Arranging a flat plate having an adhesive surface to which an adherend is adhered, with the adhesive surface as an upper surface;
An application step of applying an adhesive to each of the adhesive surfaces of the flat plate disposed;
A semi-curing step to increase the viscosity coefficient of the applied adhesive;
A planarization step of planarizing the surface by removing at least a portion of the surface of the adhesive having an increased viscosity coefficient;
Adhering the adherend to the flattened surface of the adhesive; and
And subsequently curing the adhesive,
The planarization step includes
A first mask having a first opening, wherein the first opening is covered by a first net provided substantially flush with the upper surface of the first mask; At a position where the first opening is above the adhesive surface, at least a part of the first net is bitten into the adhesive and is attached to the flat plate, and at least a part of the adhesive is attached. Exposing on the first net;
And a step of sliding the squeegee over the surface of the first net to remove the adhesive exposed above the first net. The application step includes
Attaching a second mask having a second opening to the flat plate at a position where the opening is above the bonding surface;
Supplying the adhesive on the second mask;
Sliding the squeegee over the surface of the second mask to move the adhesive from the second opening to the adhesive surface and applying the adhesive to the adhesive surface. 2. The bonding method according to 1. A plurality of the flat plates are arranged,
The first opening of the first mask and the second opening of the second mask are provided at positions corresponding to the respective flat plates;
The bonding method according to claim 2. Using an epoxy resin as the adhesive,
The semi-curing step increases the viscosity coefficient to at least 30000 mPa · s or more,
The adhesion method according to any one of claims 1 to 3. Using an ultraviolet curable resin as the adhesive,
The semi-curing step irradiates ultraviolet rays to increase the viscosity coefficient to at least 30000 mPa · s or more.
The adhesion method according to any one of claims 1 to 3.   The adhesion method according to any one of claims 1 to 5, wherein the roughness of the first net is in the range of 100 to 600. A method for producing an IC chip, wherein one surface of a chip body is bonded to a reinforcing plate,
Producing a plurality of said chip bodies;
Producing a plurality of said reinforcing plates;
Fixing the plurality of reinforcing plates to a base with an adhesive surface of the reinforcing plate as an upper surface;
The step of bonding the chip body to the reinforcing plate using the bonding method according to any one of claims 1 to 6, wherein the chip body is the adherend and the reinforcing plate is the flat plate. Have
IC chip manufacturing method. The thickness of the IC chip is 75 μm or less,
The thickness of the adhesive after the flattening step is 50 μm or less.
The manufacturing method of the IC chip according to claim 7.

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