CN105551950B - Grinding method of package substrate - Google Patents

Abstract

Provided is a method of grinding a package substrate, which enables thinning of the sealing resin layer of the package substrate to a desired thickness with a single cutting device without having a grinding device. The cutting device includes a first cutting member having a first flat grinding whetstone and a second cutting member having a second flat grinding whetstone, a package substrate has a sealing resin layer for sealing the back surfaces of the plurality of devices with resin, and the method A protective member sticking step; a holding step; after the holding step is performed, the first flat grinding whetstone is brought into contact with the sealing resin layer, and the first flat grinding whetstone and the package substrate are relatively moved in the grinding feed direction to The first grinding step in which the sealing resin layer is ground to the first thickness; after the first grinding step is performed, the second flat grinding stone is brought into contact with the sealing resin layer, and the second flat grinding stone is ground with the package substrate. A 2nd grinding process which relatively moves in a cutting feed direction and grinds a sealing resin layer to a desired thickness finally.

Description

Grinding method of package substrate

technical field

The present invention relates to a method of grinding a package substrate, wherein the sealing resin layer of the package substrate is ground to a desired thickness.

Background technique

In a package substrate such as a CSP (Chip Size Package) or a QFN (Quad Flat Non-leaded Package), the front surfaces of a plurality of devices having a plurality of electrodes are respectively aligned with the electrodes. The substrates (lead frames) are arranged so as to face each other at a predetermined interval, and the backside of the device arranged on the electrode substrate is resin-sealed, and the package substrate is divided into individual package devices by a cutting device, and the packaged devices after the division are widely used. It is used in various electronic devices such as mobile phones and personal computers.

In recent years, with the miniaturization and weight reduction of electronic devices such as mobile phones and personal computers, the miniaturization and thinning of each packaged device are also advancing. As a technique for achieving downsizing and thinning, before dividing a package substrate into individual package devices, grinding the sealing resin on the back surface of the package substrate to a desired thickness, and then dividing it into individual package devices ( For example, refer to Japanese Patent Laid-Open No. 2011-181641 and Japanese Patent Laid-Open No. 2014-015490).

Patent Document 1: Japanese Patent Laid-Open No. 2011-181641

Patent Document 2: Japanese Patent Laid-Open No. 2014-015490

SUMMARY OF THE INVENTION

However, the methods disclosed in Patent Document 1 and Patent Document 2 require a grinding device for grinding the back surface of the package substrate before dividing the package substrate into individual package devices, which is wasteful.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a method of grinding a package substrate capable of thinning the sealing resin layer of the package substrate to a desired thickness with a single cutting device even without a grinding device. thickness of.

According to the present invention, there is provided a method for grinding a package substrate, wherein the sealing resin layer of the package substrate is ground to a desired thickness using a cutting device, wherein the cutting device includes a first cutting member having a mounting a disk-shaped first flat grinding grindstone attached to the end of the first main shaft; and a second cutting member having a disk-shaped second flat grinding grindstone attached to the end of the second main shaft In the package substrate, the front surface of the device having a plurality of electrodes is opposed to the electrode substrate, and a plurality of devices are arranged on the electrode substrate with a predetermined interval, and the package substrate has a resin to be arranged on the electrode substrate. The sealing resin layer for sealing the back surfaces of a plurality of devices on an electrode substrate, and the method for grinding a packaging substrate, characterized by comprising a step of attaching a protective member to the front side of the packaging substrate to be integrally mounted. On the protective member on the annular frame; the holding step is to suck and hold the front side of the package substrate to which the protective member is attached by the chuck table of the cutting device; the first grinding step is performed after the holding step , the first flat grinding stone is brought into contact with the sealing resin layer on the back side of the package substrate, and the first flat grinding stone and the package substrate are relatively moved in the grinding feed direction, and the The sealing resin layer of the package substrate is ground to a first thickness; and a second grinding step, after the first grinding step is performed, the second flat grinding grindstone and the back surface side of the package substrate are ground. The sealing resin layer of the packaging substrate is finally ground to a desired thickness by relatively moving the second flat grinding stone and the packaging substrate in the grinding feed direction while the sealing resin layer is in contact with each other.

Preferably, the disk-shaped first flat grinding stone and the disk-shaped second flat grinding stone are fixed to the outer periphery of the wheel base by means of a disk-shaped wheel base and nickel plating. It is composed of electroplated grindstone layer on the surface.

It is preferable that the average abrasive grain diameter of the said disk-shaped 2nd flat-grinding grindstone is equal to or less than the average abrasive-grain diameter of the said disk-shaped 1st flat-grinding grindstone.

In the present invention, the disk-shaped first flat grinding stone and the disk-shaped second flat grinding stone are respectively attached to the main shafts of the dual-spindle cutting device, and the sealing resin layer is sealed by the first flat grinding stone. Rough grinding to the first thickness, and final grinding of the sealing resin layer to the desired thickness by the second flat grinding stone, so even without a grinding device, the sealing substrate can be efficiently ground by a single cutting device. Seal the resin layer.

Description of drawings

FIG. 1 is a perspective view of a cutting device suitable for carrying out the grinding method of the present invention.

FIG. 2 is an exploded perspective view of the first cutting unit.

3 is a schematic side view of the first and second cutting units.

FIG. 4 is a plan view of the package substrate.

FIG. 5 is a side view of the package substrate.

6 is a perspective view showing a holding member sticking process.

7 is a cross-sectional view illustrating a rough grinding step.

8 is a cross-sectional view illustrating a final grinding step.

Label description

2: Cutting device; 6: Chuck table; 11: Package substrate; 16A: First cutting unit; 16B: Second cutting unit; 29: Sealing resin layer; 44: First flat grinding stone; 44B: First cutting unit 2 flat grinding grindstones.

Detailed ways

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Referring to FIG. 1 , there is shown a perspective view of a cutting device 2 suitable for implementing the method of grinding a package substrate of the present invention. 4 is a base of the cutting device 2, and a chuck table 6 is arranged on the base 4 so as to be capable of reciprocating in the X-axis direction by a cutting feed mechanism (not shown), and the chuck table 6 Arranged to be rotatable. 8 is a corrugated cover covering the cutting feed mechanism.

The cassette mounting table 10 is arranged on the base 4 so as to be able to ascend and descend in the vertical direction (Z-axis direction) by a cassette lifter (elevating member) not shown. A cassette 12 for accommodating a workpiece is placed on the cassette mounting table 10 .

A gate-shaped first column 14 is erected at the rear of the base 4 , and the first cutting unit 16A and the second cutting unit 16B are attached to the first column 14 so as to be movable in the Y-axis direction and the Z-axis direction. . The first and second cutting units 16A and 16B include disk-shaped flat-grinding grindstones 44 and 44B attached to the ends of the rotationally driven spindles.

As shown in FIG. 2 , the first cutting unit 16A includes a main shaft 36 rotatably accommodated in the main shaft housing 34 , and a mounting flange 38 is attached to the distal end of the main shaft 36 and is fixed by a nut 40 . Further, a disk-shaped flat grinding stone 44 is attached to the attachment flange 38 and fixed by the fixing nut 42 .

As shown in the schematic side view of FIG. 3 , a disk-shaped first flat grinding stone 44 is attached to the distal end portion of the main shaft 36 of the first cutting unit 16A, and the distal end portion of the main shaft 36B of the second cutting unit 16B is attached. A disk-shaped second flat grinding grindstone 44B is attached. The cutting device 2 according to the present embodiment is a cutting device of opposing dual-spindles in which the first flat grinding grindstone 44 and the second flat grinding grindstone 44B are arranged to face each other.

Here, both the first flat grinding grindstone 44 and the second flat grinding grindstone 44B are formed by electroplating diamond abrasive grains on the outer peripheral surface of the wheel base with nickel plating. The average abrasive grain diameter of the diamond abrasive grains of the second flat grinding grindstone 44B is preferably equal to or smaller than the average abrasive grain diameter of the diamond abrasive grains of the first flat grinding grindstone 44 . In addition, the width of the first and second flat grinding grindstones 44 and 44B in the present embodiment is 15 mm.

4, a top view of the package substrate 11 is shown. The package substrate 11 has, for example, a rectangular-shaped electrode substrate (lead frame) 13. In the electrode substrate 13, in the region surrounded by the peripheral remaining region 15 and the non-device region 15a, there are three device regions 17a, 17b, 17c.

In each of the device regions 17a, 17b, and 17c, a plurality of device forming portions 23 are formed to be divided. The device forming portions 23 are divided by first and second planned dividing lines 21a and 21b arranged vertically and horizontally so as to be perpendicular to each other. A plurality of electrodes 25 are formed on the forming portion 23 .

The electrodes 25 are insulated from each other from the electrode substrate 13 by the molded resin. By cutting the first line to be divided 21a and the second line to be divided 21b, electrodes 25 of each device appear on both sides thereof.

As shown in FIG. 5 , the device 27 is adhered to the back surface of each device forming portion 23 in the device regions 17a, 17b, and 17c via a DAF (Die Attach Film) 35, and the electrode of each device 27 is connected to the electrode 25. .

Further, each device 27 in the device regions 17a, 17b, and 17c is sealed with resin, and a sealing resin layer 29 is formed on the back surface of each device region 17a, 17b, and 17c. As shown in FIG. 4 , circular holes 19 are formed in the four corners of the electrode substrate 13 .

Next, the grinding method of the package board|substrate of this invention using the cutting apparatus 2 comprised as mentioned above is demonstrated. In the grinding method of the package substrate of the present invention, first, a protective member sticking step is performed, and the front surface 11a side of the package board 11 is adhered to the protective member integrally mounted on the ring-shaped frame F.

That is, as shown in FIG. 6, the front surface 11a side of the package substrate 11 is attached to the dicing tape T as a protective member, and the outer peripheral portion of the dicing tape T is attached to the ring frame F. Thereby, the sealing resin layer 29 of the package substrate 11 is exposed.

After the protective member sticking step is carried out, the front surface 11 a side of the package substrate 11 to which the dicing tape T as the protective member is stuck is sucked and held by the chuck table 6 via the dicing tape T, and is clamped and fixed by the jig 7 . Ring Frame F.

Next, as shown in FIG. 7 , a rough grinding step (first grinding step) is performed, and a disk-shaped first flat grinding that rotates at a high speed (for example, 20000 rpm) of the spindle 36 attached to the first cutting unit 16A is performed. The grindstone 44 is in contact with the sealing resin layer 29 on the back surface 11b side of the package substrate 11, and the first flat grinding grindstone 44 and the package substrate 11 held on the chuck table 6 are moved in the grinding feed direction (X axis). The sealing resin layer 29 of the package substrate 11 is ground to the first thickness by the first flat grinding grindstone 44 by relatively moving in the direction) at a predetermined processing feed speed. Here, the first thickness is thicker than the final thickness t1 of the package substrate 11 by a predetermined amount.

The grinding conditions of the rough grinding step are, for example, as follows.

Spindle 36 speed: 20000rpm

Processing feed rate (grinding feed rate): 50mm/s

The index amount of the flat grinding grindstone 44: 7mm (the overlap amount is 8mm)

After the rough grinding step (first grinding step) is performed, as shown in FIG. 8 , the final grinding step (second grinding step) is performed, and the spindle 36B attached to the second cutting unit 16B is rotated at high speed ( For example, a disk-shaped second flat grinding stone 44B at 20000 rpm is brought into contact with the sealing resin layer 29 of the package substrate 11 on which the rough grinding process has been performed, and the flat grinding stone 44B is held on the chuck table 6 . The sealing resin layer 29 of the sealing resin layer 29 of the packaging substrate 11 is ground to the final thickness t1 by relatively moving at a predetermined processing feed speed in the grinding feed direction (X-axis direction).

The processing conditions of the final grinding step are as follows, for example.

Spindle speed: 20000rpm

Processing feed rate (grinding feed rate): 50mm/s

Standard amount of flat grinding grindstone 44B: 7mm (overlapping amount is 8mm)

In addition, in the present embodiment, both the rough grinding step and the final grinding step are performed by fixing the flat grinding grindstones 44 and 44B in the X-axis direction, and at a predetermined machining feed rate in the X-axis direction. The chuck table 6 performs processing and feeding.

First, rough grinding is performed by the first flat grinding grindstone 44 having a relatively large average abrasive grain diameter to a thickness close to the final thickness t1, and the remaining thickness is finalized by the second flat grinding grinding stone 44B having a relatively small average abrasive grain diameter. Since it is ground to the final thickness t1, the sealing resin layer 29 can be ground efficiently, and the ground surface can be finished beautifully.

Claims (3)

1. A grinding method of a sealing substrate, which grinds a sealing resin layer of the sealing substrate to a desired thickness using a cutting device, wherein the cutting device comprises: a 1 st cutting member having a 1 st disc-shaped flat grinding stone attached to a tip end of a 1 st main shaft; and a 2 nd cutting member having a 2 nd flat grinding stone of a disk shape attached to a tip end of the 2 nd spindle, wherein the package substrate has a plurality of devices disposed on an electrode substrate with a predetermined interval therebetween with a front surface of the devices having a plurality of electrodes facing the electrode substrate, and the package substrate has the sealing resin layer sealing back surfaces of the devices disposed on the electrode substrate with a resin, the method for grinding the package substrate comprising the steps of:

a protective member sticking step of sticking the front surface side of the package substrate to a protective member integrally mounted on the annular frame;

a holding step of performing suction holding of the front surface side of the package substrate to which the protective member is attached by a chuck table of a cutting device;

a 1 st grinding step of grinding the sealing resin layer of the package substrate to a 1 st thickness by bringing the 1 st flat grinding stone into contact with the sealing resin layer on the back surface side of the package substrate and relatively moving the 1 st flat grinding stone and the package substrate in a grinding feed direction after the holding step is performed; and

and a 2 nd grinding step of, after the 1 st grinding step is performed, bringing the 2 nd flat grinding stone into contact with the sealing resin layer on the back surface side of the package substrate, and relatively moving the 2 nd flat grinding stone and the package substrate in a grinding feed direction to finally grind the sealing resin layer of the package substrate to a desired thickness.

2. The grinding method of a package substrate according to claim 1,

the disk-shaped 1 st and 2 nd flat grinding stones are composed of a disk-shaped wheel base and an electroplated grinding stone layer in which abrasive grains are fixed to the outer peripheral surface of the wheel base by nickel plating.

3. The grinding method of a package substrate according to claim 1 or 2,

the average abrasive grain diameter of the disk-shaped 2 nd flat grinding stone is equal to or less than the average abrasive grain diameter of the disk-shaped 1 st flat grinding stone.

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