Expansion film, manufacturing method for an expansion film and method for expanding an expansion film

Abstract

An expansion film adapted to be held and expanded by an expansion device in the state in which a plate-like workpiece is attached to the expansion film, the expansion device comprising a first holding unit and a second holding unit that oppose each other, with the workpiece being inserted therebetween in a first direction, the first holding unit and the second holding unit being movable away from each other in the first direction, the expansion device further comprising a third holding unit and a fourth holding unit that oppose each other, with the workpiece being inserted therebetween in a second direction perpendicular to the first direction, the third holding unit and the fourth holding unit being movable away from each other in the second direction, the expansion film having a circumferential region around the workpiece at which the expansion film is adapted toto be held by the first holding unit, the second holding unit, the third holding unit and the fourth holding unit; wherein the expansion film comprises: , a base film; and an adhesion-promoting layer formed on the base film, the adhesion-promoting layer having an adhesion promoter adapted to be reduced by application of ultraviolet light; the adhesion of the adhesion-promoting layer in the peripheral area of the expansion film is lower than the adhesion of the adhesion-promoting layer in the other area of the expansion film.

Description

BACKGROUND OF THE INVENTIONTechnical field

[0001] The present invention relates to an expansion film adapted to be expanded in the state where a workpiece is attached to the expansion film, and also relates to a manufacturing method of an expansion film and a method for expanding an expansion film. Description of the state of the art

[0002] As a method for dividing a plate-like workpiece such as a semiconductor wafer into a plurality of chips, a machining method has been practically employed that includes the steps of focusing a laser beam into the workpiece to thereby form a modified layer (modified region) in the workpiece, and then applying an external force to the workpiece to divide the workpiece along the modified layer (see, for example, Japanese Patent Application Laid-Open No. 2002-192370). In this machining method, an expansion film attached to a workpiece is expanded to thereby apply an external force to the workpiece, thereby dividing the workpiece into a plurality of device chips.

[0003] As another method, a machining method has been proposed that utilizes an external force applied to the workpiece during grinding or polishing of the workpiece after a modified layer is formed in the workpiece, thereby dividing the workpiece into a plurality of chips along the modified layer (see, for example, PCT application WO 2003 / 077295 A1). After dividing the workpiece into a plurality of chips in this machining method, the expansion film attached to the workpiece is expanded to increase a distance between adjacent ones of the plurality of chips. In this case, it is possible to prevent damage to each chip due to contact with the adjacent chips when handling each chip later.

[0004] Recently, an expansion device capable of expanding an expansion film in desired directions (see, for example, Japanese Patent Application Laid-Open No. 2014-22382) has been put into practice. The expansion device includes a first holding unit (first holding means) and a second holding unit (second holding means) facing each other, with a workpiece inserted therebetween in a first direction substantially parallel to the expansion film in the state where the workpiece is attached to the expansion film. The expansion device further includes a third holding unit (third holding means) and a fourth holding unit (fourth holding means) facing each other, with the workpiece inserted therebetween in a second direction perpendicular to the first direction in a plane parallel to the expansion film.The first holding unit and the second holding unit are movable away from each other in the first direction, and the third holding unit and the fourth holding unit are movable away from each other in the second direction. These four holding units are actuated to hold four sections of the expansion film. Then, the first holding unit and the second holding unit are moved away from each other in the first direction, and the third holding unit and the fourth holding unit are moved away from each other in the second direction, so that the expansion film can be expanded in both the first direction and the second direction. US 2006 0 154 066 A1 relates to a wafer processing belt with an adhesion-promoting layer. JP 2014 022 382 A relates to a belt expansion device. WO 2011 158 835 A1 relates to an adhesion-promoting tape. PRESENTATION OF THE INVENTION

[0005] The expansion film has an adhesive layer that provides adhesion on the top (or bottom) surface. Accordingly, if both sides of the expansion film, which has the adhesive layer, are held by each holding unit, there is a possibility that the expansion film cannot be removed from the holding unit later.

[0006] It is therefore an object of the present invention to provide an expansion film that can be easily removed from each holding unit of the expansion device.

[0007] Another object of the present invention is to provide a manufacturing method for this expansion film.

[0008] It is a further object of the present invention to provide an expansion method for this expansion film.

[0009] In accordance with one aspect of the present invention, there is provided an expansion film adapted to be held and expanded by an expansion device in the state that a plate-like workpiece is attached to the expansion film, wherein the expansion device includes a first holding unit and a second holding unit which are opposed to each other with the workpiece sandwiched therebetween in a first direction, the first holding unit and the second holding unit are movable away from each other in the first direction, the expansion device further comprises a third holding unit and a fourth holding unit which are opposed to each other with the workpiece sandwiched therebetween in a second direction perpendicular to the first direction, wherein the expansion film has a circumferential region around the workpiece where the expansion film is adapted to be held and expanded by the first holding unit, the second holding unit,the third holding unit and the fourth holding unit; the expansion film includes a base film; and an adhesion-promoting layer is formed on the base film, wherein the adhesion-promoting layer comprises an adhesion promoter adapted to be reduced by the application of ultraviolet light; the adhesion of the adhesion-promoting layer in the peripheral region of the expansion film is lower than the adhesion of the adhesion-promoting layer in the other region of the expansion film.

[0010] The expansion film may be elongated and formed as a film roll. In this case, the expansion film is rolled up as a film roll in the first direction, and the peripheral region of the expansion film includes a plurality of first low adhesion regions arranged at given intervals in the first direction, each first low adhesion region extending in the second direction across the entire width of the base film, and a pair of second low adhesion regions extending in the first direction along opposite side edges of the base film.

[0011] In accordance with another aspect of the present invention, there is provided a manufacturing method for an expansion film adapted to be held and expanded by an expansion device in the state in which a plate-like workpiece is attached to the expansion film, wherein the expansion device includes a first holding unit and a second holding unit that oppose each other, with the workpiece inserted therebetween in a first direction, the first holding unit and the second holding unit being movable away from each other in the first direction, the expansion device further includes a third holding unit and a fourth holding unit that oppose each other, with the workpiece inserted therebetween in a second direction perpendicular to the first direction, the third holding unit and the fourth holding unit being movable away from each other in the second direction,the expansion film has a circumferential region around the workpiece, at which the expansion film is adapted to be held by the first holding unit, the second holding unit, the third holding unit, and the fourth holding unit; the manufacturing method comprises a preparation step for preparing an original expansion film comprising a base film and an adhesive layer formed on the base film, wherein the adhesive layer has an adhesive layer adapted to be reduced by applying ultraviolet light; and an ultraviolet light application step for selectively applying ultraviolet light to only a circumferential region of the original expansion film corresponding to the circumferential region of the expansion film,whereby the adhesion of the adhesion-promoting layer in the peripheral area of the original expansion film is reduced compared to the adhesion of the adhesion-promoting layer in the other area of the original expansion film.

[0012] In accordance with another aspect of the present invention, there is provided an expansion method for an expansion film including a base film and an adhesive layer on the base film, the adhesive layer having an adhesive adapted to be reduced by application of ultraviolet light, the expansion method including a first attaching step of attaching a plate-like workpiece to the expansion film;a holding step of holding the expansion film using a first holding unit and a second holding unit that oppose each other with the workpiece sandwiched therebetween in a first direction, and also expanding it using a third holding unit and a fourth holding unit that oppose each other with the workpiece sandwiched therebetween in a second direction perpendicular to the first direction, after or before performing the first attaching step; an expanding step of moving the first holding unit and the second holding unit away from each other in the first direction and also moving the third holding unit and the fourth holding unit away from each other in the second direction after performing the first attaching step and the holding step, thereby expanding the expansion film in both the first direction and the second direction;a second attachment step of attaching an annular frame having an inner opening larger than the size of the workpiece to the expansion film in the state where the workpiece is inserted into the inner opening of the annular frame after performing the expansion step; a cutting step of cutting the expansion film along the annular frame after performing the second attachment step;and an ultraviolet light application step of selectively applying ultraviolet light to only a peripheral region of the expansion film in which the expansion film is adapted to be held by the first holding unit, the second holding unit, the third holding unit, and the fourth holding unit, before performing the holding step, whereby the adhesion of the adhesion-promoting layer in the peripheral region of the expansion film is reduced compared with the adhesion of the adhesion-promoting layer in the other region of the expansion film.

[0013] In the expansion film according to the present invention, the adhesion of the adhesion-promoting layer is lower in the peripheral region held by the first holding unit, the second holding unit, the third holding unit, and the fourth holding unit than in the other regions of the expansion film. Accordingly, the expansion film can be easily removed from each holding unit.

[0014] In the manufacturing method for the expansion film according to the present invention, ultraviolet light is selectively applied to the adhesive layer only in a peripheral region of the original expansion film corresponding to the peripheral region of the expansion film as a product, thereby reducing the adhesion of the adhesive layer in the peripheral region of the original expansion film compared to the adhesion of the adhesive layer in the other region of the original expansion film. Accordingly, the above-described expansion film can be easily manufactured.In the expansion method for the expansion film according to the present invention, ultraviolet light is selectively applied to the adhesive layer only in the peripheral region of the expansion film before holding the expansion film in this peripheral region using the first, second, third, and fourth holding units, thereby reducing the adhesion of the adhesive layer in this peripheral region compared to the adhesion of the adhesive layer in the other region. Accordingly, the expansion film can be easily removed from each holding unit after expanding the expansion film.

[0015] The above and other objects, features and advantages of the present invention and the mode of carrying them out will become clearer and the invention itself best understood by studying the following description and appended claims with reference to the attached figures which show a preferred embodiment of the invention. SHORT DESCRIPTION OF THE CHARACTERS Fig. 1A is a schematic view of an expansion film according to a preferred embodiment of the present invention; Fig. 1B is a schematic sectional view of an expansion film; Fig. 2A and Fig. 2B are schematic sectional views showing a manufacturing process of the expansion film; Fig. 3 is a schematic perspective view showing the state in which the expansion film is held by an expansion device; Fig. 4 is a schematic perspective view showing the state in which a workpiece has been attached to the expansion film; Fig. 5 is a schematic perspective view showing the state in which the expansion film has been expanded by the expansion device; Fig. 6 is a schematic perspective view showing the state in which an annular frame has been attached to the expansion sheet; Fig. 7 is a schematic perspective view showing the state in which the expansion film has been cut along the annular frame; Fig. 8 is a schematic specific view showing the state in which ultraviolet light is applied to a portion of the expansion film; Fig. Fig. 9 is a schematic sectional view showing the state in which each chip is removed from the portion of the expansion film; and Fig. 10 is a schematic perspective view showing an expansion film according to a modification of this preferred embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] A preferred embodiment of the expansion film in accordance with the invention will now be described with reference to the attached figures. Fig. Fig. 1A is a schematic perspective view of an expansion film 1 according to this preferred embodiment and Fig. Figure 1B is a schematic sectional view of the expansion film 1 shown in Fig. 1A. As shown in Fig. 1A and Fig. As shown in Fig. 1B, the expansion sheet 1 includes a base sheet 3 having a first surface (top surface) 3a and a second surface (bottom surface) 3b. An adhesive layer 5 is formed on a first surface 3a of the base sheet 3. The base sheet 3 is formed of a plastic such as polyolefin or polyvinyl chloride. The base sheet 23 is rectangular in plan view. However, the shape, material, etc. of the base sheet 3 are not limited, provided that the base sheet 3 can be suitably expanded using an expansion device described below.The adhesion-promoting layer 5 is formed of an ultraviolet-curing resin that can be cured by ultraviolet light. The adhesion of the adhesion-promoting layer 5 to the expansion film 1 is set lower in one peripheral region held by the expansion jig than in the other region. Examples of the ultraviolet-curing resin include acrylic resin and rubber resin. In other words, the peripheral region of the expansion film 1 held by the expansion jig is formed by a low-adhesion region A where the adhesion of the adhesion-promoting layer 5 is relatively low.In contrast, the other region of the expansion film 1 is a central region surrounded by the low adhesion region A, and this central region is formed by a high adhesion region B where the adhesion promoting effect of the adhesion promoting layer 5 is relatively large. By applying ultraviolet light to the ultraviolet curing resin forming the adhesion promoting layer 5, the ultraviolet curing resin is cured or partially cured to thereby reduce the adhesion promoting effect. Accordingly, by utilizing this phenomenon, it is possible to form the expansion film 1 having a low adhesion promoting effect region A and a high adhesion promoting effect region B. The adhesion promoting effect of the adhesion promoting layer 5 in the low adhesion promoting effect region A may be completely lost. That is,that the area A with low adhesion of the adhesion-promoting layer 5 cannot exhibit any adhesion.

[0017] Fig. 2A and Fig. 2B are schematic sectional views showing a manufacturing process for the expansion film 1. In manufacturing the expansion film 1 according to this preferred embodiment, a preparatory step is first performed to prepare an original expansion film having the base film 3 and the adhesive layer 5 on the first surface 3a of the base film 3 as shown in Fig. 2A. This original expansion film is an expansion film processed by ultraviolet light. In this state, the adhesion of the adhesion-promoting layer 5 is substantially uniform over the entire surface of the original expansion film.

[0018] After performing the preparation step, an ultraviolet light application step is performed to selectively apply ultraviolet light only to a peripheral area of the adhesion-promoting layer 5 corresponding to the low adhesion area A as shown in Fig. 2B. In the ultraviolet light application step, a mask 7 is used to block ultraviolet light, so that a central area of the adhesion-promoting layer 5 corresponding to the high adhesion area B, as shown in Fig. 2B. In this preferred embodiment, the mask 7 is applied to the second surface (lower surface) 3b of the base film 3 in the central region corresponding to the high adhesion region B, as shown in Fig. 2B. Accordingly, upon later removal of the mask 7, the mask 7 can be easily removed without adhesion to the adhesion-promoting layer 5. By setting the mask 7 as described above, ultraviolet light from a light source 9 is applied through the base film 3 onto the adhesion-promoting layer 5. The light source 9 is located below the second surface 3b of the base film 3. As described above, the mask 7 is set so as to cover the central region of the adhesion-promoting layer 5 corresponding to the high adhesion region B. Furthermore, the base film 3 can transmit ultraviolet light in this preferred embodiment. Accordingly, ultraviolet light emitted from the light source 9 is also selectively applied only to the peripheral region of the adhesion-promoting layer 5 corresponding to the low adhesion region A (the region not covered by the mask 7).As a result, the adhesion-promoting layer 5 is cured or partially cured in the peripheral region by the ultraviolet light applied by the light source 9. Thereafter, the mask 7 is removed from the base film 3. In this way, the expansion film 1 is formed as shown in FIG. Fig. 2B, where the expansion film 1 has the low adhesion promoting region A where the adhesion promoting layer 5 has been reduced, and the adhesion promoting region B has not been reduced. In the case where the base film 3 does not transmit ultraviolet light, the mask 7 may be set on the adhesion promoting layer 5 in its central region, and the light source 9 may be located above the adhesion promoting layer 5. Accordingly, ultraviolet light is directly applied from the light source 9 to the adhesion promoting layer 5. In this case, the surface of the mask 7 may preferably be treated with fluoroplastic so that adhesion promoting layer 5 is prevented.

[0019] The following describes an expansion method for an expansion film, which includes the above-mentioned manufacturing method for an expansion film 1 as a part of the expansion method. First, the preparation step and the ultraviolet light application step of the above-described manufacturing method of the expansion film 1 are performed, to thereby obtain the expansion film 1 having a low adhesion promoter region A formed on the expansion film and a high adhesion promoter region B surrounded by the low adhesion promoter region A, wherein the adhesion promoter layer 5 is lower in the low adhesion promoter region A than in the high adhesion promoter region B.

[0020] After performing the ultraviolet light application step, a holding step is performed to hold the expansion film 1 using an expansion device 2 as shown in Fig. 3 shown. Fig. Fig. 3 is a schematic perspective view showing the state in which the expansion film 1 was held by the expansion device 2. In Fig. 3 also shows a circular area C in which a plate-like workpiece 11 (see Fig. 4) is to be installed later. As in Fig. 3, the expansion device 2 includes a first holding unit (first holding means) 4 and a second holding unit (second holding means) 6 opposite each other across the surface C, that is, the workpiece 11 is sandwiched therebetween in a first direction D1 substantially parallel to the expansion film 1. Similarly, the expansion device 2 further includes a third holding unit (third holding means) 8 and a fourth holding unit (fourth holding means) 10 opposite each other across the surface C, sandwiched therebetween in a second direction D2 substantially parallel to the expansion film 1 perpendicular to the first direction D1. The first holding unit 4 and the second holding unit 6 are supported by respective horizontal moving mechanisms (not shown) so that they can be moved away from each other in the first direction D1.Similarly, the third holding unit 8 and the fourth holding unit 10 are supported by respective horizontal moving mechanisms (not shown) so that they can be moved away from each other in the second direction D2.

[0021] Each of the first holding unit 4, the second holding unit 6, the third holding unit 8, and the fourth holding unit 10 includes an upper support member 12 adapted to be placed above the expansion film 1 (above the adhesive layer 5), and a lower support member 14 adapted to be placed below the expansion film 1 (below the second surface 3b of the base film 3). Each of the upper support member 12 and the lower support member 14 is a beam-like member extending in a predetermined direction and having a length greater than the diameter of the circular region C.Specifically, the upper support member 12 and the lower support member 14 included in each of the first and second holding units 4 and 6 extend in the second direction D2, whereas the upper support member 12 and the lower support member 14 included in the third and fourth holding units 8 and 10 extend in the first direction D1. A plurality of contact members 16 are mounted on each upper support member 12 at the lower side thereof. Similarly, a plurality of contact members 16 are mounted on the lower support member 14 at the upper side thereof. Each contact member 16 is a cylindrical member rotatable about its axis in the state of being in contact with the expansion film 1.The rotation axes of the plurality of contact elements 16 included in each of the first and second holding units 4 and 6 are parallel to the first direction D1, whereas the rotation axes of the plurality of contact elements 16 included in each of the third and fourth holding units 8 and 10 are parallel to the second direction D2.

[0022] When holding the expansion film 1 using the holding units 4, 6, 8 and 10, the low adhesion area A of the expansion film 1 is formed between the upper support member 12 and the lower support member 14 of each holding unit as shown in Fig. 3. In other words, the low adhesion region A surrounding the high adhesion region B of the expansion film 1 is held by the first holding unit 4, the second holding unit 6, the third holding unit 8, and the fourth holding unit 10 in such a manner that the plurality of contact elements 16 of each holding unit come into contact with the low adhesion region A of the expansion film 1.

[0023] After performing the holding step, a first attachment step is performed to attach the plate-like workpiece 11 to the expansion film 1 as shown in Fig. 4 shown. Fig. 4 is a schematic perspective view showing the state in which the workpiece 11 has been attached to the expansion film 1. In this preferred embodiment, the workpiece 11 is a circular wafer formed of a semiconductor such as silicon. The workpiece 11 has a first surface (front side) 11a and a second surface (back side) 11b. The first surface 11a of the workpiece 11 is configured from a central device region and a peripheral edge region surrounding the device region. The device region is divided by a plurality of intersecting dividing lines (streets) to form a plurality of separated regions on which a plurality of devices 13 such as integrated circuits (ICs) and large-scale integrations (LSIs) are formed. A modified layer (not shown) as a division starting point is previously formed inside the workpiece 11 along each dividing line.This modified layer can be formed by applying a laser beam having a transmission wavelength to the workpiece 11 along each dividing line so that the laser beam is focused in the workpiece 11. As a modification, a groove can be formed on the workpiece 11 along each dividing line by laser cutting or ablation. In this case, the groove formed along each dividing line is used as a dividing starting point instead of the modified layer.

[0024] In this preferred embodiment, the second surface 11b of the workpiece 11 is bonded to the adhesion-promoting layer 5 of the expansion film 1 in the circular area C (see Fig. 3), the circular region C having the same size as that of the workpiece 11. The circular region C is formed in the high-adhesion region B of the expansion film 1. While a circular wafer formed of a semiconductor such as silicon is used as the workpiece 11 in this preferred embodiment, the workpiece 11 is not limited in its material, shape, structure, etc. For example, a substrate formed of a ceramic, a plastic, or a metal can be used as the workpiece 11. Further, a wafer or substrate previously divided into a plurality of device chips can be used as the workpiece 11. In this case, the distance between adjacent ones of the plurality of device chips constituting the workpiece 11 is increased by expanding the expansion film 1 in the following step.

[0025] After performing the first application step, an expansion step is carried out to apply the expansion film 1 as shown in Fig. 5 shown, to train. Fig. 5 is a schematic perspective view showing the state in which the expansion film 1 has been expanded by the expansion device 2. When expanding the expansion film 1, the horizontal movement mechanisms for movably supporting the first holding unit 4 and the second holding unit 6 are operated to move the first holding unit 4 and the second holding unit 6 away from each other in the first direction D1. Furthermore, the horizontal movement mechanisms for movably supporting the third holding unit 8 and the fourth holding unit 10 are operated to move the third holding unit 8 and the fourth holding unit 10 away from each other in the second direction D2. As a result, the expansion film 1 is expanded in both the first direction D1 and the second direction D2, as shown in Fig. 5, whereby a tensile force is applied to the workpiece 11 in both the first direction D1 and the second direction D2.

[0026] Each of the first and second holding units 4 and 6, which can be moved away from each other in the first direction D1, includes the plurality of contact elements 16, each rotatable about an axis parallel to the first direction D1. Similarly, each of the third and fourth holding units 8 and 10, which can be moved away from each other in the second direction D2, includes the plurality of contact elements 16, each rotatable about an axis parallel to the second direction D2. Accordingly, the expansion film 1 is held by the first and second holding units 4 and 6 so that it can be displaced in the second direction D2 by rotation of the contact elements 16 of the third and fourth holding units 8 and 10. Similarly, the expansion film 1 is held by the third and fourth holding units 8 and 10 so that it can be displaced in the first direction D1 by rotation of the contact elements 16 of the first and second holding units 4 and 6.In other words, the area A held by the first and second holding units 4 and 6 can also be appropriately extended in the second direction D2, and the area A held by third and fourth holding units 8 and 10 can also be appropriately extended in the first direction D1.

[0027] In this way, the expansion film 1 is expanded to thereby apply a tensile force to the workpiece 11 in both the first direction D1 and the second direction D2. As a result, the workpiece 11 is divided along each dividing line where the modified layer is formed, thereby obtaining a plurality of chips and also increasing the distance between adjacent ones of the plurality of chips. In order to properly divide the workpiece 11 and sufficiently increase the distance between adjacent chips, the directions of extension of the orthogonal dividing lines are preferably aligned with the first and second directions D1 and D2 as shown in Fig. 5, in order to efficiently utilize the external force generated by the expansion of the expansion film 1.

[0028] After performing the forming step, a second attachment step is performed to attach an annular frame 21 to the expansion film 1, as shown in Fig. 6 shown. Fig. Fig. 6 is a schematic perspective view showing the state in which the annular frame 21 is attached to the expansion film 1. As in Fig. 6, the annular frame 21 has an inner opening 21a larger than the workpiece 11. The annular frame 21 is attached to the adhesive layer 5 of the expansion film 1 so as to surround the workpiece 11, that is, the circular region C of the expansion film 1. In other words, the workpiece 11 attached to the circular region C of the expansion film 1 is inserted into the inner opening 21a of the annular frame 21. In this way, the annular frame 21 is attached to the expansion film 1 so as to surround the workpiece 11. In this preferred embodiment, the annular frame 21 is attached to the expansion film 1 so as to surround the workpiece 11 in the state where the expansion film 1 remains expanded. Accordingly, even after the expansion of the expansion film 1 is stopped, the increased distance between adjacent chips can be maintained.

[0029] After performing the second attachment step, a cutting step is performed to cut the expansion film 1 along the annular frame 21 as shown in Fig. 7 shown to cut. Fig. Fig. 7 is a schematic perspective view showing the state in which the expansion film 1 has been cut along the annular frame 21. For example, the expansion film 1 is cut along the annular frame 21 from the second surface 3b of the base film 3 at a radial position between the inner periphery of the annular frame 21 and the outer periphery thereof. By performing this cutting step, a frame unit 25 as shown in Fig. 7, the frame unit 25 is composed of a workpiece 11 that has already been divided into chips, the annular frame 21, and a portion 23 of the expansion film cut from the expansion film 1. After obtaining the frame unit 25, the remaining expansion film 1 is removed from the expansion device 2. At this time, the remaining part of the expansion film 1 can be easily removed from the expansion device 2 because the low-adhesion region A of the expansion film 1 is held by the holding units 4, 6, 8, and 10 of the expansion device 2, and the adhesion of the adhesion-promoting layer 5 is lower in the low-adhesion region A than in the high-adhesion region B to which the workpiece 11 and the annular frame 21 are attached.

[0030] After performing the cutting step, a reduction step of the adhesion promotion is carried out in which ultraviolet light is applied to the section 23 of the expansion film of the frame unit 25, whereby the adhesion promotion of the adhesion-promoting layer 5 of the section 23 of the expansion film, as shown in Fig. 8 shown, is reduced. Fig. Fig. 8 is a schematic perspective view showing the state in which ultraviolet light is applied to the portion 23 of the expansion film. In this preferred embodiment, ultraviolet light is emitted from the light source 9 located below the base film 3 (the second surface 3b) of the portion 23 of the expansion film, as shown in Fig. 8. As described above, the base film 3 of the expansion film 1, i.e., the portion 23 of the expansion film, can transmit ultraviolet light. Accordingly, the ultraviolet light emitted by the light source 9 is applied through the base film 3 to the adhesion-promoting layer 5 of the portion 23 of the expansion film. As a result, the adhesion of the adhesion-promoting layer 5 of the portion 23 of the expansion film can be reduced over its entire area, thereby facilitating the removal of chips from the portion 23 of the expansion film, which will be described later.

[0031] After performing the reduction step of the adhesion promotion, a pickup step is performed to remove each chip from the portion 23 of the expansion film, as shown in Fig. 9 shown. Fig. Fig. 9 is a schematic sectional view showing the state in which each chip 15 is picked up by the portion 23 of the expansion film. The adhesion of the adhesion-promoting layer 5 of the portion 23 of the expansion film has been reduced in the adhesion reduction step described above. Accordingly, each chip 15 can be easily removed from the portion 23 of the expansion film as shown in Fig. 9. Thereafter, each chip 15 picked up from the portion 28 of the expansion film is mounted on a selected circuit board or the like for actual use.

[0032] As described above, the expansion film 1 according to this preferred embodiment has a peripheral region (low adhesion region A) held by the first holding unit (first holding means) 4, the second holding unit (second holding means) 6, the third holding unit (third holding means) 8, and the fourth holding unit (fourth holding means) 10. The adhesion of the adhesion-promoting layer 5 is lower in this peripheral region than in the other region (high adhesion region B). Accordingly, the expansion film 1 can be easily removed from the holding unit.

[0033] Furthermore, in the manufacturing method for the expansion film 1, ultraviolet light is selectively applied to the adhesion-promoting layer 5 only in a peripheral region of the original expansion film corresponding to the low adhesion-promoting region A of the expansion film 1, thereby reducing the adhesion of the adhesion-promoting layer 5 in this peripheral region compared to the adhesion of the adhesion-promoting layer in the remaining region corresponding to the high adhesion-promoting region B of the expansion film 1. Consequently, the expansion film 1 having the low adhesion-promoting region A and the high adhesion-promoting region B can be easily manufactured.

[0034] Furthermore, in the expansion process for the expansion film 1, ultraviolet light is selectively applied to the adhesion-promoting layer 5 only in a peripheral region of the original expansion film corresponding to the low adhesion-promoting region A of the expansion film 1, thereby reducing the adhesion of the adhesion-promoting layer 5 in this peripheral region compared to the adhesion of the adhesion-promoting layer 5 in the other region corresponding to the high adhesion-promoting region B of the expansion film 1. Accordingly, the expansion film 1 can be easily removed from each holding unit after the expansion of the expansion film 1.

[0035] The present invention is not limited to the preferred embodiment, but various modifications may be made. For example, while the first attachment step is performed after the holding step in the expansion film stretching method according to the above preferred embodiment, the holding step may be performed after the first attachment step. In this case, the ultraviolet light application step may be performed between the first attachment step and the holding step.

[0036] Furthermore, while the base sheet 3 of the expansion sheet 1 according to the above preferred embodiment has a rectangular shape in a plan view, the shape of the base sheet of the expansion sheet according to the present invention is not limited. Fig. Fig. 10 is a schematic perspective view showing an expansion film 31 according to a modification of the above preferred embodiment. As shown in Fig. As shown in Fig. 10, the expansion film 31 according to this modification is formed as a film roll 35 in the state where a separator 33 like a sheet of separated paper is attached to the adhesive side of the expansion film 31. The basic configuration of the expansion film 31 is the same as that of the expansion film 1 described above. Accordingly, the same parts as those of the expansion film 1 are designated by the same reference numerals, and a detailed description thereof will be omitted.

[0037] The expansion film 31 includes an elongated base film 3 and an adhesive layer 5 formed on the first surface 3a of the base film 3 over its entire area. Specifically, the base film 3 of the expansion film 31 is longer than the base film 3 of the expansion film 1 in the first direction D1 along which the expansion film 31 is rolled. In contrast, the width of the base film 3 of the expansion film 31 in the second direction D2 is the same as the length of the base film 3 of the expansion film 1 in the second direction D2. The adhesiveness of the adhesive layer 5 of the expansion film 31 is set to be lower in a predetermined region held by the expansion jig 2 than in the other region.Specifically, a plurality of first low adhesion regions A1 are arranged at given intervals in the first direction D1, each low adhesion region A1 extending in the second direction D2 across the entire width of the base film 3. Further, a pair of second low adhesion regions A2 extend in the first direction D1 along the opposite side edges of the base film 3. Similarly, a plurality of rectangular high adhesion regions B are formed so as to be surrounded by the first low adhesion regions A1 and the second low adhesion regions A2. The adhesion of the adhesion-promoting layer 5 in the first and second low adhesion regions A1 and A2 is set to be lower than that in the high adhesion regions B.When using the expansion film 31, the film roll 35 is rolled up to spread the expansion film 31, and the dividing line 33 is next detached from the expansion film 31.

Claims

[1] An expansion film adapted to be held and expanded by an expansion device in the state in which a plate-like workpiece is attached to the expansion film, the expansion device comprising a first holding unit and a second holding unit which oppose each other, with the workpiece being inserted therebetween in a first direction, the first holding unit and the second holding unit being movable away from each other in the first direction, the expansion device further comprising a third holding unit and a fourth holding unit which oppose each other, with the workpiece being inserted therebetween in a second direction perpendicular to the first direction, the third holding unit and the fourth holding unit being movable away from each other in the second direction, the expansion film having a circumferential region around the workpiece at which the expansion film is adapted toto be held by the first holding unit, the second holding unit, the third holding unit and the fourth holding unit; wherein the expansion film comprises:, a base film; and an adhesion-promoting layer formed on the base film, the adhesion-promoting layer having an adhesion promoter adapted to be reduced by application of ultraviolet light; the adhesion of the adhesion-promoting layer in the peripheral area of the expansion film is lower than the adhesion of the adhesion-promoting layer in the other area of the expansion film. [2] The expansion film according to claim 1, wherein the expansion film is elongated and formed as a film roll; the expansion film is rolled up as the film roll in the first direction; the peripheral region of the expansion film includes a plurality of first low adhesion regions arranged at given intervals in the first direction, each first low adhesion region extending in the second direction across the entire width of the base film, and a pair of second low adhesion regions extending in the first direction along the opposite side edges of the base film. [3] A manufacturing method for an expansion film adapted to be held by an expansion device in the state in which a plate-like workpiece is attached to the expansion film, the expansion device including a first holding unit and a second holding unit facing each other, with the workpiece being inserted therebetween in a first direction, the first holding unit and the second holding unit being movable away from each other in the first direction, the expansion device further including a third holding unit and a fourth holding unit facing each other, with the workpiece being inserted therebetween in a second direction perpendicular to the first direction, the third holding unit and the fourth holding unit being movable away from each other in the second direction, the expansion film having a circumferential region around the workpiece at which the expansion film is adapted toto be held by the first holding unit, the second holding unit, the third holding unit and the fourth holding unit; wherein the manufacturing method comprises:, a preparation step of preparing an original expansion film comprising a base film and an adhesive layer formed on the base film, wherein the adhesive layer comprises an adhesive adapted to be reduced by applying ultraviolet light; and an ultraviolet light application step of selectively applying ultraviolet light to only a peripheral region of the original expansion film corresponding to the peripheral region of the expansion film, thereby reducing the adhesion promotion of the adhesion-promoting layer in the peripheral region of the original expansion film compared to the adhesion promotion of the adhesion-promoting layer in the other region of the original expansion film. [4] An expansion method for an expansion film including a base film and an adhesion-promoting layer formed on the base film, the adhesion-promoting layer having an adhesion promoter adapted to be reduced by applying ultraviolet light, the expansion method comprising: a first attaching step for attaching a plate-like workpiece to the expansion film; a holding step of holding the expansion film using a first holding unit and a second holding unit that oppose each other with the workpiece being interposed therebetween in a first direction, and also using a third holding unit and a fourth holding unit that oppose each other with the workpiece being interposed therebetween in a second direction perpendicular to the first direction, before or after the first attaching step is performed; an expanding step of moving the first holding unit and the second holding unit away from each other in the first direction and also moving the third holding unit and the fourth holding unit away from each other in the second direction after performing the first attaching step and the holding step, thereby expanding the expanding film in both the first direction and the second direction; a second attaching step of attaching an annular frame having an inner opening larger than the workpiece to the expansion film in the state where the workpiece is inserted into the inner opening of the annular frame after performing the forming step; a cutting step for cutting the expansion film along the annular frame after performing the second attachment step; and an ultraviolet light application step of selectively applying ultraviolet light to only a peripheral region of the expansion film at which the expansion film is adapted to be held by the first holding unit, the second holding unit, the third holding unit, and the fourth holding unit, before performing the holding step, whereby the adhesion of the adhesion-promoting layer in the peripheral region of the expansion film is reduced compared to the adhesion of the adhesion-promoting layer in the other region of the expansion film.

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