Package substrate processing method

Abstract

To provide a package substrate processing method capable of suppressing a cost for forming a stepwise step with prescribed accuracy on a cross section of a package chip.SOLUTION: A package substrate cutting method includes a holding step, a warpage relaxing step, a groove forming step, and a dividing step. The holding step holds a package substrate 1 on a chuck table 110. The warpage relaxing step forms a groove 51 having a first depth 61 along division schedule lines of the package substrate 1 to relax warpage of the package substrate 1 using a first cutting blade 121 after performing the holding step. The groove forming step forms a groove having a second depth by further cutting the groove 51 having the first depth 61 using the first cutting blade 121 after performing the warpage relaxing step. The dividing step divides the package substrate 1 to form package chips by further cutting the groove having the second depth using a second cutting blade thinner than the first cutting blade 121 after performing the groove forming step.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a method for processing a package substrate. [Background technology]

[0002] Semiconductor devices mounted on various electronic devices are packaged chips covered with mold resin. It is known that packaged chips are manufactured by dividing a package substrate, which is constructed by covering a semiconductor device wafer with mold resin, or by mounting a semiconductor device chip on a resin or metal frame and further covering the device chip with mold resin, along a planned division line (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-206995 A Summary of the Invention [Problem to be solved by the invention]

[0004] The package substrate is heated when it is covered with the mold resin, and when it is cooled, the mold resin shrinks, causing it to warp when it is separated into package chips. Therefore, even if it is held by a chuck table during cutting, it still warps slightly, but it is divided by a so-called full cut, for example, by strongly sucking it with the chuck table or by fixing the package substrate to tape on a frame.

[0005] However, when making the cross section of a package chip stepped, for example when forming a package chip called a wettable flank, a certain level of precision is required for the stepped steps. Therefore, when forming a half-cut groove in a warped package substrate to form a stepped cross section, there was a problem that the warp was gradually alleviated, making it impossible to cut the entire package substrate to the same depth.

[0006] Furthermore, a method was devised in which the height of the package substrate was measured in advance, and then the cutting depth of the cutting blade was controlled in accordance with the variation in height to form a stepped cross section. However, this required additional measuring equipment and a control program, which resulted in high costs.

[0007] The present invention has been made in consideration of such problems, and its object is to provide a processing method for a package substrate that can reduce the cost of forming a stepped step with a predetermined accuracy on the cross section of a packaged chip. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, a processing method for a package substrate of the present invention is a cutting method for a package substrate in which a device arranged in an area partitioned by a division line is sealed with a resin, the cutting method including: a holding step of holding the package substrate on a chuck table; a warp reducing step of, after the holding step, using a first cutting blade to form a groove of a first depth along the division line of the package substrate and reducing warp of the package substrate; a groove forming step of, after the warp reducing step, using the first cutting blade to further cut the groove of the first depth to form a groove of a second depth; and a division step of, after the groove forming step, using a second cutting blade thinner than the first cutting blade to further cut the groove of the second depth to divide the package substrate and form package chips. The package substrate includes a metal frame having a chip mounting area on which a device chip is mounted and an electrode portion disposed around the chip mounting area and projecting toward the division line, and a molding resin for sealing the device chip mounted on the metal frame. The electrode portion of the package chip has a cut surface of the electrode portion formed in a stepped shape by a groove of the second depth, and includes a plating step for plating the electrode portion between the groove forming step and the division step. This is what we have in mind. Effect of the Invention

[0011] The present invention can reduce the cost of forming a stepped portion with a predetermined accuracy on the cross section of a packaged chip. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a top view showing a package substrate which is an object to be processed by the method for processing a package substrate according to the first embodiment. [Diagram 2] FIG. 2 is a bottom view showing the package substrate of FIG. [Diagram 3] FIG. 3 is a cross-sectional view showing a cross section along the longitudinal direction of the package substrate in FIG. [Figure 4] FIG. 4 is a cross-sectional view showing a cross section along the short-side direction of the package substrate in FIG. [Diagram 5] FIG. 5 is a top view showing a state in which the package substrate of FIG. 1 is supported by an annular frame. [Figure 6] FIG. 6 is a perspective view showing a packaged chip obtained by dividing the package substrate of FIG. [Figure 7] FIG. 7 is a perspective view showing a configuration example of a processing apparatus for carrying out the processing method for a package substrate according to the first embodiment. [Figure 8] FIG. 8 is a flowchart illustrating an example of a processing procedure of the processing method for the package substrate according to the first embodiment. [Figure 9] FIG. 9 is a cross-sectional view illustrating the holding step of FIG. [Figure 10] FIG. 10 is a cross-sectional view illustrating the warpage reducing step of FIG. [Figure 11] FIG. 11 is an enlarged cross-sectional view showing the package substrate after the warpage mitigation step of FIG. 8 is performed. [Figure 12] FIG. 12 is a cross-sectional view illustrating the groove forming step of FIG. [Figure 13] FIG. 13 is an enlarged cross-sectional view of the package substrate after the groove forming step of FIG. 8 is performed. [Figure 14] FIG. 14 is an enlarged cross-sectional view illustrating the plating step of FIG. [Figure 15] FIG. 15 is a cross-sectional view illustrating the dividing step of FIG. [Figure 16] FIG. 16 is an enlarged cross-sectional view of the package substrate after the dividing step of FIG. 8 is performed. [Figure 17] FIG. 17 is a perspective view showing a configuration example of a processing apparatus for carrying out the processing method for a package substrate according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The form (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiment. Furthermore, the components described below include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the configurations described below can be appropriately combined. Furthermore, various omissions, substitutions, or modifications of the configurations can be made without departing from the gist of the present invention.

[0014] [Embodiment 1] A method for processing a package substrate according to a first embodiment of the present invention will be described with reference to the drawings. First, this specification describes a package substrate 1, which is an object of the method for processing a package substrate according to the first embodiment, with reference to the drawings. FIG. 1 is a top view showing a package substrate 1, which is an object of the method for processing a package substrate according to the first embodiment. FIG. 2 is a bottom view showing the package substrate 1 of FIG. 1. FIG. 3 is a cross-sectional view showing a cross section along the longitudinal direction of the package substrate 1 of FIG. 1. FIG. 4 is a cross-sectional view showing a cross section along the lateral direction of the package substrate 1 of FIG. 1. FIG. 5 is a top view showing a state in which the package substrate 1 of FIG. 1 is supported by an annular frame 32. FIG. 6 is a perspective view showing a package chip 40 obtained by dividing the package substrate 1 of FIG. 1.

[0015] The package substrate 1 has a surface on which devices are arranged in regions defined by a plurality of division lines formed along a first direction and a second direction intersecting the first direction (orthogonal in the first embodiment), and the devices are sealed with resin. In the first embodiment, the package substrate 1 includes a metal frame 10 and a molded resin 20 (an example of a resin according to the present invention) as shown in Figs. 1 to 4. The metal frame 10 is made of metal and is a flat plate having a rectangular planar shape. As shown in Fig. 1, the package substrate 1 has a chip mounting region 13 (an example of a region according to the present invention) defined by a plurality of division lines 12 formed along the longitudinal direction and the lateral direction on the surface 11 of the metal frame 10, and a device chip 14 (an example of a device according to the present invention) is arranged in the chip mounting region 13. The molded resin 20 is made of, for example, a thermosetting resin. As shown in Figs. 2 to 4, the molded resin 20 seals the device chip 14 mounted in the chip mounting region 13 of the metal frame 10 on the surface 11 of the metal frame 10.

[0016] In the package substrate 1 of the first embodiment, a plurality of (16 in the example shown in FIG. 1) chip mounting areas 13 are arranged adjacent to each other with a division line 12 in between. In the first embodiment, the metal frame 10 of the package substrate 1 is a QFN package (Quad For Non-lead package) substrate having a leadless structure in which electrode pads are formed as connection terminals instead of leads, and includes a plurality of chip mounting areas 13, electrode parts 15 corresponding to the electrode pads of the QFN package arranged around each chip mounting area 13 and protruding to the division line 12, and a surplus area 16 surrounding the plurality of chip mounting areas 13 arranged adjacent to each other and arranged in a group, and in which no device chip 14 is mounted. 1, the electrode parts 15 are formed on the back surface 17 opposite to the front surface 11 of the metal frame 10, straddling the planned division line 12 from the outer periphery of the device chip 14 mounted in the chip mounting area 13 to the adjacent chip mounting area 13 or surplus area 16 across the planned division line 12, to a thickness equal to or greater than a second depth 62 (see FIG. 6 etc.) described later. The front surface 11 side of the chip mounting area 13 and the electrode parts 15 of the package substrate 1 are both covered with mold resin 20, and the back surface 17 side is not covered with mold resin 20 and is exposed.

[0017] The mold resin 20 is formed so as to cover the front surface 11 side of the multiple chip mounting areas 13 arranged adjacent to each other. In the example shown in Figures 1 to 4, the package substrate 1 has three groups of multiple chip mounting areas 13 arranged in the longitudinal direction, and the mold resin 20 is formed in three places corresponding to these groups of multiple chip mounting areas 13 arranged in the longitudinal direction.

[0018] Due to the difference in thermal shrinkage rate between the metal frame 10 and the molded resin 20, the package substrate 1 is curved in a direction that is convex toward the metal frame 10 side and concave toward the molded resin 20 side when viewed from the side, as shown in Figures 3 and 4, and has a warp.

[0019] In embodiment 1, as shown in FIG. 5, the package substrate 1 has a dicing tape 31 attached to the front surface 11 side on which the molded resin 20 is formed, and the outer edge of the dicing tape 31 is attached to annular frame 32, so that the package substrate 1 is supported by the dicing tape 31 in the opening of the annular frame 32 with the back surface 17 side exposed.

[0020] The package substrate 1 is divided into package chips 40 shown in FIG. 6 by forming grooves 52 (see FIG. 12 and FIG. 13) of a second depth 62 along the division lines 12 of each chip mounting area 13 and then cutting the widthwise center portion of the grooves 52 by a processing method of the package substrate described later. The package chip 40 is a QFN package chip, and as shown in FIG. 6, the chip mounting area 13 mounting the device chip 14 is arranged in the center, and the electrode portion 15 corresponding to the electrode pad of the QFN package chip is arranged on the outer edge. The electrode portion 15 of the package chip 40 is fixed to a wiring board such as a printed circuit board, for example, via solder. The grooves 52 of the second depth 62 form step portions 41 of the second depth 62 from the back surface 17 all around the outer edge of the package chip 40, and the outer edge including the cut surface of the electrode portion 15 is formed in a stepped shape, thereby increasing the contact area of ​​the solder on the electrode portion 15.

[0021] Next, this specification will explain a processing apparatus 100 that performs the processing method for a package substrate according to embodiment 1 with reference to the drawings. Fig. 7 is a perspective view showing a configuration example of the processing apparatus 100 that performs the processing method for a package substrate according to embodiment 1. As shown in Fig. 7, the processing apparatus 100 includes a chuck table 110, a processing unit 120, an imaging unit 130, an X-axis moving unit 141, a Y-axis moving unit 142, a Z-axis moving unit 143, and a control unit 150.

[0022] The chuck table 110 has a disk-shaped frame body with a recess formed therein and a disk-shaped suction part fitted in the recess. The suction part of the chuck table 110 is formed of a porous porous ceramic or the like, and is connected to a vacuum suction source (not shown) via a vacuum suction path (not shown). The upper surface of the suction part of the chuck table 110 is a holding surface 111 on which the package substrate 1 is placed and which suction-holds the placed package substrate 1. In the first embodiment, the package substrate 1 is placed on the holding surface 111 with the back surface 17 facing upward, and the held surface 111 suction-holds the placed package substrate 1 from the front surface 11 side via the dicing tape 31. The holding surface 111 and the upper surface of the frame body of the chuck table 110 are arranged on the same plane and are formed parallel to the horizontal XY plane. The chuck table 110 is movable in the X-axis direction, which is one horizontal direction, by an X-axis moving unit 141, and is rotatable around an axis parallel to the Z-axis direction, which is vertical and perpendicular to the holding surface 111, by a rotary drive source not shown.

[0023] In addition, as shown in FIG. 1, the chuck table 110 is provided with four clamps 112 which are frame holding parts arranged on the outer periphery of the frame body and which hold and fix the annular frame 32 attached to the package substrate 1 via the dicing tape 31.

[0024] As shown in FIG. 7, the processing unit 120 has a first cutting blade 121, a second cutting blade 122, and a spindle 123. The first cutting blade 121 and the second cutting blade 122 are each attached to the tip of the spindle 123 in a detachable and replaceable manner. The first cutting blade 121 and the second cutting blade 122 are both rotated by the spindle 123 around an axis parallel to a Y-axis direction that is another horizontal direction and perpendicular to the X-axis direction, to cut the package substrate 1 held on the chuck table 110. The processing unit 120 is provided so as to be movable in the Y-axis direction by a Y-axis moving unit 142 with respect to the package substrate 1 held on the chuck table 110, and is provided so as to be movable in the Z-axis direction by a Z-axis moving unit 143.

[0025] In the first embodiment, the first cutting blade 121 and the second cutting blade 122 have annular cutting edges formed at a first thickness 126 (see FIGS. 10 and 12) and a second thickness 127 (see FIG. 15), respectively. The cutting edge of the second cutting blade 122 is thinner than the cutting edge of the first cutting blade 121, i.e., the second thickness 127 is smaller than the first thickness 126.

[0026] In the first embodiment, the first cutting blade 121 and the second cutting blade 122 have a cutting edge of a so-called metal bond type blade made of abrasive grains such as diamond or CBN (Cubic Boron Nitride) and a bond material such as metal or resin. The first cutting blade 121 and the second cutting blade 122 may be a hub blade having a hub or a hubless blade without a hub. The first cutting blade 121 and the second cutting blade 122 are not limited to this in the present invention, and may have a cutting edge of an electroformed bond type blade in which abrasive grains are fixed to a plating layer, or may have a cutting edge of a saw-tooth metal saw formed of a thin steel plate blade made of a superhard alloy obtained by sintering high-speed steel, tungsten carbide, cobalt, nickel, or the like.

[0027] The processing apparatus 100 uses the X-axis moving unit 141, the Y-axis moving unit 142, and the Z-axis moving unit 143 to set the first cutting blade 121 or the second cutting blade 122 attached to the tip of the spindle 123 at a predetermined position relative to the package substrate 1 held on the chuck table 110, and moves the first cutting blade 121 or the second cutting blade 122 attached to the tip of the spindle 123 relative to the package substrate 1 along the planned division line 12 while rotating, thereby cutting the package substrate 1 along the planned division line 12 with the first cutting blade 121 or the second cutting blade 122 attached to the tip of the spindle 123.

[0028] In the first embodiment, the imaging unit 130 is fixed to the processing unit 120 so as to move integrally with the processing unit 120. The imaging unit 130 includes an imaging element that images the back surface 17 (exposed surface) and the planned division lines 12 of the package substrate 1 before cutting held on the chuck table 110. The imaging element is, for example, a CCD (Charge-Coupled Device) imaging element or a CMOS (Complementary MOS) imaging element. The imaging unit 130 images the back surface 17 of the package substrate 1 before cutting held on the chuck table 110, etc., to obtain an image for performing alignment to align the package substrate 1 with the first cutting blade 121 or the second cutting blade 122 attached to the tip of the spindle 123, and outputs the obtained image to the control unit 150.

[0029] The control unit 150 controls the operation of various components of the processing apparatus 100 to cause the processing apparatus 100 to perform the processing method for a package substrate according to the first embodiment. In this embodiment, the control unit 150 includes a computer system. The computer system included in the control unit 150 includes an arithmetic processing device having a microprocessor such as a CPU (Central Processing Unit), a storage device having a memory such as a ROM (Read Only Memory) or a RAM (Random Access Memory), and an input / output interface device. The arithmetic processing device of the control unit 150 performs arithmetic processing according to a computer program stored in the storage device of the control unit 150, and outputs a control signal for controlling the processing apparatus 100 to each component of the processing apparatus 100 via the input / output interface device of the control unit 150.

[0030] The processing apparatus 100 further includes a cassette placement table 160, a cleaning unit (not shown), and a transport unit (not shown). The cassette placement table 160 is a placement table on which a cassette, which is a container for storing a plurality of package substrates 1, is placed, and the placed cassette is raised and lowered in the Z-axis direction. The cleaning unit cleans the package substrate 1 after cutting, and removes foreign matter such as cutting chips attached to the package substrate 1. The transport unit (not shown) transports the package substrate 1 before cutting from inside the cassette onto the chuck table 110, transports the package substrate 1 after cutting from the chuck table 110 to the cleaning unit, and transports the package substrate 1 after cleaning from the cleaning unit into the cassette.

[0031] Next, this specification describes a processing method for a package substrate according to the first embodiment with reference to the drawings. FIG. 8 is a flow chart showing an example of a processing procedure of the processing method for a package substrate according to the first embodiment. FIG. 9 is a cross-sectional view explaining the holding step 1001 in FIG. 8. FIG. 10 is a cross-sectional view explaining the warpage reduction step 1002 in FIG. 8. FIG. 11 is an enlarged cross-sectional view showing the package substrate 1 after the warpage reduction step 1002 in FIG. 8 is performed. FIG. 12 is a cross-sectional view explaining the groove formation step 1003 in FIG. 8. FIG. 13 is an enlarged cross-sectional view showing the package substrate 1 after the groove formation step 1003 in FIG. 8 is performed. FIG. 14 is an enlarged cross-sectional view explaining the plating step 1004 in FIG. 8. FIG. 15 is a cross-sectional view explaining the division step 1005 in FIG. 8. FIG. 16 is an enlarged cross-sectional view showing the package substrate 1 after the division step 1005 in FIG. 8 is performed. The processing method for a package substrate according to embodiment 1 is an example of an operational process performed by processing apparatus 100, and includes a holding step 1001, a warpage reduction step 1002, a groove formation step 1003, a plating step 1004, and a division step 1005, as shown in FIG. 8.

[0032] 9, the holding step 1001 is a step of holding the package substrate 1 on the chuck table 110. In the holding step 1001, first, as shown in FIG. 5, the dicing tape 31 is attached to the front surface 11 side of the package substrate 1, and the annular frame 32 is attached to the outer edge of the dicing tape 31, so that the package substrate 1 is supported by the dicing tape 31 in the opening of the annular frame 32 with the back surface 17 side exposed. In the holding step 1001, the control unit 150 then uses the transport unit to place the package substrate 1 supported by the dicing tape 31 in the opening of the annular frame 32 on the holding surface 111 of the chuck table 110 with the back surface 17 facing upward, and the package substrate 1 placed on the holding surface 111 is sucked and held by the chuck table 110 from the front surface 11 side via the dicing tape 31, and the annular frame 32 attached to the package substrate 1 via the dicing tape 31 is held by the clamp 112.

[0033] The warpage reduction step 1002 is performed after the holding step 1001, and is a step of forming a groove 51 of a first depth 61 along the division line 12 of the package substrate 1 by using a first cutting blade 121 to reduce warpage of the package substrate 1, as shown in Figs. 10 and 11. In the warpage reduction step 1002, the first cutting blade 121 is first attached to the tip of the spindle 123. In the warpage reduction step 1002, the control unit 150 then rotates the first cutting blade 121 and moves it relative to the package substrate 1 along the division line 12, thereby cutting the package substrate 1 from the rear surface 17 side along the division line 12 with the first cutting blade 121, thereby forming a groove 51 of a first depth 61 and a width corresponding to a first thickness 126 along the division line 12 of the package substrate 1. In this manner, in the warpage mitigation step 1002, by forming grooves 51 of a first depth 61 along the planned division lines 12 of the package substrate 1, the difference in shear stress that has arisen between the metal frame 10 and the molded resin 20 due to the difference in thermal shrinkage rates between the metal frame 10 and the molded resin 20 is mitigated, thereby mitigating the warpage of the package substrate 1.

[0034] The first depth 61 of the groove 51 is set to an arbitrary value smaller than the second depth 62 of the groove 52 formed in a groove forming step 1003 described below. The first depth 61 of the groove 51 can sufficiently fulfill the function of reducing warpage of the package substrate 1 (e.g., reducing warpage to 50% or less), and is preferably set to a value sufficiently smaller than the second depth 62 of the groove 52 (e.g., 70% or less of the second depth 62).

[0035] In the warpage mitigation step 1002, in the first embodiment, the grooves 51 of the first depth 61 are formed along all the planned division lines 12 of the package substrate 1, but the present invention is not limited to this, and the grooves 51 of the first depth 61 may be formed only along a preselected portion of the planned division lines 12. By forming the grooves 51 of the first depth 61 along the multiple planned division lines 12 in the warpage mitigation step 1002, at least one remaining groove 51 fulfills the function of mitigating warpage of the package substrate 1 when the grooves 51 of the first depth 61 are further cut to form grooves 52 of the second depth 62 in the groove formation step 1003 performed thereafter.

[0036] In the warpage mitigating step 1002, for example, the grooves 51 of the first depth 61 may be formed only along the division lines 12 along the first direction (longitudinal direction), or the grooves 51 of the first depth 61 may be formed only along the division lines 12 along the second direction (short direction). In the warpage mitigating step 1002, for example, the grooves 51 of the first depth 61 may be formed only along a preselected part of the division lines 12 along the first direction (longitudinal direction), or the grooves 51 of the first depth 61 may be formed only along a preselected part of the division lines 12 along the second direction (short direction). In the warpage mitigating step 1002, the division lines 12 along which the grooves 51 of the first depth 61 are formed can be appropriately changed according to the warpage of the package substrate 1.

[0037] The groove forming step 1003 is performed after the warpage reduction step 1002, and is a step of further cutting the groove 51 of the first depth 61 using the first cutting blade 121 to form a groove 52 of a second depth 62 deeper than the first depth 61, as shown in FIG. 12 and FIG. 13. The groove forming step 1003 is performed following the warpage reduction step 1002, with the first cutting blade 121 attached to the tip of the spindle 123. In the warpage reduction step 1002, the control unit 150 rotates the first cutting blade 121 and moves it relative to the package substrate 1 along the division lines 12, thereby cutting the package substrate 1 from the rear surface 17 side along the division lines 12 with the first cutting blade 121, thereby forming a groove 52 of the second depth 62 and a width corresponding to the first thickness 126 along the division lines 12 of the package substrate 1. The second depth 62 of the groove 52 is set to the same value as the desired depth of the step portion 41 to be formed on the outer edge of the package chip 40. In the groove forming step 1003, before forming the groove 52, the position of the cutting blade 121 is adjusted so that the center of the thickness of the cutting blade 121 is located at the center of the width direction of the groove 51, and adjustment is made so that a step-like step is not formed on the side surface of the groove 52.

[0038] In the groove forming step 1003, in the first embodiment, cutting is performed along all the division lines 12 to form the grooves 52 of the second depth 62. In addition, in the groove forming step 1003, when the grooves 51 of the first depth 61 are formed only along a part of the division lines 12 preselected in the warpage reduction step 1002, the grooves 52 of the second depth 62 are formed by cutting also along the division lines 12 on which the grooves 51 of the first depth 61 are not formed.

[0039] The plating step 1004 is performed between the groove forming step 1003 and the division step 1005, and is a step of plating the electrode portion 15 as shown in FIG. 14. In the plating step 1004, for example, the package substrate 1 after the groove forming step 1003 and before the division step 1005 is immersed in an electrolytic plating bath for a predetermined time while applying a predetermined voltage to the electrode portion 15, thereby forming a plating film 70 of a metal such as nickel on the exposed portion of the electrode portion 15. Here, the exposed portion of the electrode portion 15 is a portion of the electrode portion 15 that is exposed on the back surface 17 of the metal frame 10 and the side and bottom surfaces of the groove 52. Note that, although the plating step 1004 is performed in the first embodiment, the present invention is not limited to this, and the plating step 1004 may be omitted.

[0040] 15 and 16, the dividing step 1005 is a step performed after at least the groove forming step 1003, or in the first embodiment, after the plating step 1004, in which a second cutting blade 122 thinner than the first cutting blade 121 is used to further cut grooves 52 of a second depth 62 to divide the package substrate 1 and form package chips 40. In the dividing step 1005, first, the second cutting blade 122 is attached to the tip of the spindle 123. In the dividing step 1005, the control unit 150 then rotates the second cutting blade 122 and moves it relative to the package substrate 1 along the dividing lines 12, thereby cutting the package substrate 1 from the rear surface 17 side along the dividing lines 12 with the second cutting blade 122, thereby cutting the widthwise center portion of the groove 52 having the second depth 62 and the width corresponding to the first thickness 126 formed in the groove forming step 1003, and forming a groove 53 having a depth reaching the front surface 11 from the rear surface 17 of the package substrate 1 and a width corresponding to the second thickness 127. In the dividing step 1005, in the first embodiment, cutting is performed along all the dividing lines 12 to form the grooves 53. In the dividing step 1005, such grooves 53 are formed along the dividing lines 12 of the package substrate 1, thereby dividing the package substrate 1 along the dividing lines 12 to form package chips 40.

[0041] The processing method for a package substrate according to the first embodiment having the above-mentioned configuration forms a shallow groove 51 in advance with a first cutting blade 121 having a thickness for forming a stepped cross section to mitigate the warpage of the package substrate 1, and forms a groove 52 of a desired depth (second depth 62) using the same first cutting blade 121. Therefore, the processing method for a package substrate according to the first embodiment can reduce the influence of the warpage of the package substrate 1 without using a measuring device or a special control program, and then form a groove 52 of a desired depth on the entire surface of the package substrate 1, thereby achieving an effect of suppressing the cost of forming a stepped step portion 41 of a predetermined accuracy on the cross section of the package chip 40 obtained by dividing the package substrate 1. In addition, the processing method for a package substrate according to the first embodiment can continuously perform a warpage reduction step 1002 for forming a shallow groove 51 and a groove formation step 1003 for forming a groove 52 of a desired depth using the same first cutting blade 121 in one processing device 100.

[0042] Furthermore, the processing method for the package substrate according to embodiment 1 exhibits the above-mentioned effects particularly remarkably in a case where the package substrate 1, which comprises the metal frame 10 and the molded resin 20, has warping due to the difference in thermal shrinkage rate between the metal frame 10 and the molded resin 20, and is a QFN package substrate with a leadless structure, and therefore it is necessary to form a stepped step portion 41 with a predetermined precision on the cross section of the package chip 40 obtained by dividing the package substrate 1, and it is possible to fix the electrode portion 15 of the package chip 40 to a wiring substrate such as a printed circuit board via solder with a predetermined precision and at low cost.

[0043] In addition, the processing method for the package substrate according to embodiment 1 includes a plating step 1004 for plating the electrode portions 15 between the groove forming step 1003 and the dividing step 1005. Therefore, the plating film 70 formed by the plating process improves the wettability of the solder of the electrode portions 15 of the package chip 40. This further improves the accuracy of fixing the electrode portions 15 of the package chip 40 to a wiring board such as a printed circuit board via solder.

[0044] [Embodiment 2] A processing method for a package substrate according to a second embodiment of the present invention will be described with reference to the drawings. Fig. 17 is a perspective view showing a configuration example of a processing apparatus 100-2 that performs the processing method for a package substrate according to the second embodiment. In Fig. 17, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0045] First, this specification describes a processing apparatus 100-2 that performs a processing method for a package substrate according to the second embodiment, with reference to the drawings. As shown in FIG. 17, the processing apparatus 100-2 is obtained by changing the chuck table 110 in the processing apparatus 100 of the first embodiment to a chuck table 110-2, and the other configurations are generally the same. The chuck table 110-2 is a so-called jig chuck table that changes a jig on the upper surface side (holding surface side) that holds the package substrate 1 in correspondence with the package substrate 1, and has a table base 115 and a holding plate 116 corresponding to the jig, as shown in FIG. 17. The holding plate 116 corresponding to the package substrate 1 is detachably attached to the upper surface 118 of the table base 115.

[0046] The table base 115 is connected to a rotary drive source (not shown) and is provided so as to be rotatable about the Z axis by the rotary drive source (not shown). The table base 115, like the chuck table 110, is provided so as to be movable in the X axis direction by an X axis moving unit 141 and so as to be rotatable about an axis parallel to the Z axis direction by a rotary drive source (not shown).

[0047] The holding plate 116 is a rectangular, flat member (holding member) corresponding to the package substrate 1 in a plan view. The holding plate 116 has an upper surface formed with a surface for suction-holding the package substrate 1, and a lower surface formed so as to be detachably attached to the table base 115. By attaching the lower surface side of the holding plate 116 to the table base 115, the upper surface of the holding plate 116 becomes parallel to the XY plane, which is a horizontal plane, and serves as a holding surface for holding the package substrate 1. In the first embodiment, the holding plate 116 is configured by, for example, covering the surface of a plate-like object made of a metal such as SUS with a urethane rubber such as nitrile rubber or ethylene rubber on the side serving as the holding surface.

[0048] 17, the holding plate 116 has a plurality of grooves formed on its upper surface at positions corresponding to the division lines 12 of the package substrate 1. These grooves are relief grooves into which a second cutting blade 122 for cutting the division lines 12 of the package substrate 1 is inserted, and are formed to be wider than the width of the division lines 12 of the package substrate 1 and the thickness of the second cutting blade 122, and deeper than the cutting depth of the second cutting blade 122. The holding plate 116 is partitioned by the plurality of grooves into a plurality of regions corresponding to each chip mounting region 13 of the package substrate 1 after it has been divided along the plurality of division lines 12.

[0049] 17, the holding plate 116 has a predetermined number of suction holes (one in the example shown in FIG. 17) formed in each of the regions corresponding to the multiple chip mounting regions 13 of the package substrate 1. All of the multiple suction holes are connected to a suction source (not shown) via a suction path formed in the table base 115 and a suction valve (not shown). Negative pressure from the suction source is introduced to the upper surface side of the holding plate 116 from the multiple suction holes via the suction path and the suction valve, and the holding plate 116 suction-holds the multiple chip mounting regions 13 of the package substrate 1 from the front surface 11 side with the back surface 17 facing upward.

[0050] Next, this specification will explain a processing method for a package substrate according to a second embodiment with reference to the drawings. The processing method for a package substrate according to the second embodiment is an example of an operation process performed by the processing apparatus 100-2, and is a process in which the holding step 1001 in the first embodiment is changed in accordance with the change of the chuck table 110 to the chuck table 110-2. In the holding step 1001 in the second embodiment, the process of attaching the dicing tape 31 to the front surface 11 side of the package substrate 1 in the first embodiment is omitted. In the holding step 1001 in the second embodiment, the control unit 150 uses the transport unit to place the package substrate 1 to which the dicing tape 31 is not attached, with the back surface 17 facing upward, on the upper surface of the holding plate 116 attached to the table base 115 of the chuck table 110-2, and the package substrate 1 placed on the upper surface of the holding plate 116 is directly sucked and held from the front surface 11 side by the chuck table 110-2.

[0051] The processing method for a package substrate according to the second embodiment having the above-mentioned configuration is obtained by changing the method for holding the package substrate 1 in the first embodiment, and since the formation of the grooves 51, 52, and 53 is the same as in the first embodiment, it has the same effect as the first embodiment. The processing method for a package substrate according to the second embodiment further has the effect of reducing the cost associated with the consumption of the dicing tape 31, since it is possible to omit the process of adhering the dicing tape 31 for holding the package substrate 1.

[0052] The present invention is not limited to the above embodiment. In other words, various modifications can be made without departing from the gist of the present invention. For example, the processing device 100 of the present invention may be equipped with two spindles 123 as the processing unit 120, and in that case, the first cutting blade 121 or the second cutting blade 122 may be attached to both spindles, or the first cutting blade 121 may be attached to one side and the second cutting blade 122 may be attached to the other side. [Explanation of symbols]

[0053] 1 Package substrate 10 Metal frame 12 Division line 13 Chip mounting area 14 Device Chip 15 Electrode section 20 Molding resin 40 Packaged Chips 41 Step 51,52,53 Groove 61 First Depth 62 Second Depth 70 Plating film 100,100-2 Processing equipment 110,110-2 Chuck table 121 First cutting blade 122 Second cutting blade

Claims

[Claim 1] A method for cutting a package substrate, the method comprising the steps of: cutting a package substrate in which a device arranged in an area defined by a division line is sealed with a resin, the method comprising the steps of: a holding step of holding the package substrate on a chuck table; a warpage reduction step of using a first cutting blade to form a groove having a first depth along the division line of the package substrate after the holding step is performed, thereby reducing warpage of the package substrate; a groove forming step of further cutting the groove of the first depth by using the first cutting blade to form a groove of a second depth after the warpage reduction step is performed; a dividing step of further cutting a groove of a second depth using a second cutting blade thinner than the first cutting blade after the groove forming step, thereby dividing the package substrate and forming package chips; Equipped with The package substrate includes a metal frame having a chip mounting area on which a device chip is mounted and an electrode portion disposed around the chip mounting area and projecting toward the division line, and a molding resin for sealing the device chip mounted on the metal frame, and the electrode portion of the package chip is cut in a stepped manner by a groove of the second depth, and The method for processing a package substrate further comprises a plating step for plating the electrode portion between the groove forming step and the dividing step.

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