JP7031962B2 - Covering member used for processing method of package substrate and processing method of package substrate - Google Patents

Description

The present invention relates to a package substrate processing method and a covering member used in the package substrate processing method.

A packaged device chip in which a semiconductor device chip is packaged with a mold resin or a metal electrode is known. Various types of package device chips such as SOP (Small Outline Package) and BGA (Ball Grid Array) are known, but QFN (Quad Flat Non-) packaged with a metal frame (lead frame) and mold resin. A package device chip called Leaded Package) is also widely distributed.

The QFN is manufactured by cutting a package substrate in which a plurality of device chips mounted on a metal frame are covered with a mold resin layer with a cutting blade and dividing them into individual device chips.

Japanese Unexamined Patent Publication No. 2007-258590

However, the conventional method for processing a package substrate has a problem in that when an electrode formed of a metal frame is cut with a cutting blade, metal burrs are generated and abnormal wear occurs due to insufficient cutting force of the cutting blade. It is a thing.

In particular, when forming a type in which a step is provided on a metal electrode as a form of a QFN package, it is necessary to cut the electrode in half. Since the ratio of cutting is very high, there is a problem that the difficulty of cutting is high, large burrs are generated, and abnormal wear of the cutting blade is likely to occur.

The present invention has been made in view of such a point, and an object of the present invention is to provide a method for processing a package substrate capable of suppressing the generation of metal burrs and preventing the occurrence of abnormal wear of a cutting blade. It is to be.

According to the present invention, a metal frame body in which a plurality of electrodes are formed along a plurality of planned division lines formed in a grid pattern that divides a region in which a device chip is mounted, and a metal frame body mounted in the region of the metal frame body. A method for processing a package substrate including a plurality of device chips and a molded resin layer laminated on the back surface side of the metal frame so as to cover the plurality of device chips, along the planned division line. A covering member mounting step in which a covering member containing no abrasive grains is laid on the surface of the package substrate on which the electrodes are exposed and the covering member is mounted on at least a plurality of scheduled division lines, and the covering member is mounted. A half-cut step in which the package substrate is cut from above the covering member with a first cutting blade to form a cutting groove on the surface of the package substrate along the planned division line at a depth at which the electrode is not fully cut. A second cutting blade thinner than the first cutting blade after performing the covering member peeling step of peeling the covering member cut in the half-cut step from the surface of the package substrate and the covering member peeling step. The center of the cutting groove is cut along the planned division line, and the package substrate is divided into individual package device chips. The covering member mounting step is heated to a predetermined temperature or higher. A liquid resin mixed with heat-expandable microspheres to be fired is laid on the surface of the package substrate, and the liquid resin is cured by heating below a predetermined temperature, irradiation with ultraviolet rays, or the passage of time to form the covering member. In the covering member peeling step, the covering member is heated to a predetermined temperature or higher to shoot the heat-expandable microspheres to form irregularities on the cured liquid resin, and the covering member made of the liquid resin is peeled off. After facilitating, the covering member is peeled off, and in the half-cut step, the cutting blade is sharpened by cutting the covering member, clogging of the cutting blade due to cutting chips of the electrode is suppressed, and the covering member is suppressed. Provided is a method for processing a package substrate, which comprises suppressing the generation of burrs on the electrode by cutting the metal .

Preferably, the covering member is composed of an adhesive tape provided with an adhesive layer whose adhesive strength is reduced by an external stimulus.

According to the method for processing a package substrate of the present invention, a covering member having an adhesive layer such as an adhesive tape or wax is laminated on a planned division line, and the electrode is half-cut along the planned division line together with the covering member. The effect of sharpening the cutting blade and removing clogging is exhibited, and it is possible to carry out half-cutting of the electrode in a good condition while suppressing the generation of metal burrs.

1A is a plan view of the package substrate, FIG. 1B is a back view of the package substrate, and FIG. 1C is a side view of the package substrate. It is a top view of the frame unit in a state where a package substrate is supported by an annular frame via a dicing tape. It is a top view which shows the covering member mounting step which mounts a covering member on the package substrate of a frame unit. It is a schematic cross-sectional view of a package substrate. It is sectional drawing which shows the half-cut step. 6 (A) is a partially enlarged plan view of the package substrate after performing the half-cut step, and FIG. 6 (B) is a sectional view taken along line 6B-6B of FIG. 6 (A). FIG. 7A is a cross-sectional view showing an external stimulus applying step, and FIG. 7B is a cross-sectional view showing a covering member peeling step. It is sectional drawing which shows the division step. It is a perspective view of a package device chip.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. With reference to FIG. 1A, a plan view of an example of a package substrate to be processed by the processing method of the present invention is shown. 1 (B) is a back view of the package substrate, and FIG. 1 (C) is a side view of the package substrate.

The package substrate 2 has a rectangular metal frame (lead frame) 4, and in the region surrounded by the outer peripheral surplus region 5 and the non-device region 5a of the metal frame 4, there are three in the illustrated example. There are device areas 6a, 6b, 6c.

In each of the device regions 6a, 6b, and 6c, the device chip mounting portions 10 are defined in a plurality of regions partitioned by the scheduled division lines 8 provided vertically and horizontally so as to be orthogonal to each other, and the individual device chip mounting portions 10 are defined. A plurality of electrodes 12 are formed along the four sides of the above.

Each of the electrodes 12 is insulated from each other by a molded resin layer 14 molded into a metal frame 4. By cutting the scheduled split line 8 extending in the first direction and the scheduled split line 8 extending in the second direction orthogonal to the first direction, the electrodes 12 of each device chip appear on both sides of the cutting groove.

A device chip (not shown) is mounted on the back surface of each device chip mounting portion 10 of the device regions 6a, 6b, and 6c, and the electrodes provided on each device chip and the electrodes 12 are connected by bonding wires.

A mold resin layer 14 is formed on the back surface of each device region 6a, 6b, 6C so that each device chip of the device regions 6a, 6b, 6c is sealed with a resin. As shown in FIG. 1 (C), the package substrate 12 has some warpage.

In carrying out the processing method of the embodiment of the present invention, as shown in FIG. 2, the back surface of the package substrate 2 is attached to a dicing tape T, which is an adhesive tape whose outer peripheral portion is attached to an annular frame F, and the frame is framed. It is charged into the cutting device in the state of the unit 16.

The most important feature of the processing method of the present invention is that the metal electrode 12 is exposed along the planned division line 8 as shown in FIG. 3 before the package substrate 2 is cut by the cutting apparatus. The covering member 18 is laid on the surface of 2, and the covering member mounting step of mounting the covering member 18 on at least the planned division line 8 is performed. In this embodiment, the covering member 18 is attached to the entire surface of the package substrate 2.

The covering member is composed of adhesive tape, wax or liquid resin. The adhesive tape includes an adhesive layer 22 whose adhesive strength is reduced by an external stimulus such as irradiation with ultraviolet rays or heating. The wax and the liquid resin are laid on the surface of the package substrate and then cured by an external stimulus (ultraviolet irradiation, heating, etc.).

The covering member 18 may be composed of an adhesive tape 18 in which abrasive grains are mixed in an adhesive layer (glue layer) 22, a thermoplastic wax in which abrasive grains are mixed, or a liquid resin in which abrasive grains are mixed.

FIG. 4 is a schematic cross-sectional view of a state in which an adhesive tape 18 as a covering member is attached on a metal frame 4 of a package substrate 2 and a mold resin layer 14 covering a device chip is formed on the back surface of the metal frame 4. The adhesive tape 18 is formed by applying an adhesive layer 22 in which abrasive grains are mixed on a base film 20.

The thermoplastic wax as the adhesive layer 22 or the covering member of the adhesive tape 18 promotes the consumption of the cutting blade when the covering member 18 is cut by the cutting blade, and can prevent the cutting blade from being clogged or unevenly worn. can.

Table 1 shows the suppression of burrs according to the type of the covering member, the wear of the blade, the thickness of the covering member, and the peeling method of the covering member after the half-cut step.

In Table 1, if there is an effect of suppressing burrs, it is marked with a circle, and if it has an effect of promoting wear of the blade, it is marked with a circle. In the above-described embodiment, it has been described that a coating member in which abrasive grains are mixed in an adhesive layer or a thermoplastic wax of an adhesive tape can be preferably used, but it is not always the case in the adhesive layer or the thermoplastic wax of the adhesive tape. It has been confirmed that there is an effect of suppressing burrs, an effect of sharpening the blade, and an effect of preventing clogging of the blade without mixing the abrasive grains.

(First Example)
Covering member attachment step: After laying the liquid resin, heat or irradiate with ultraviolet rays, or perform primary curing over time.
Covering member peeling step: Reheat at a higher temperature than the primary curing to soften the covering member, attach an adhesive tape to the covering member, and peel off at once.

(Second Example)
Covering member attachment step: A heat-expandable microsphere that fires when heated to a predetermined temperature or higher is mixed with a liquid resin. After laying the liquid resin containing microspheres, the primary curing is carried out by overheating below a predetermined temperature, irradiating with ultraviolet rays, or by elapse of time.
Coating member peeling step: The heat-expandable microspheres are fired by heating to a predetermined temperature or higher to form irregularities on the cured liquid resin to facilitate peeling.

After the covering member 18 is attached to the surface of the package substrate 2, as shown in FIG. 5, the package substrate 2 is first cut so as to be mounted on the tip of the spindle 24 (see FIG. 8) from above the covering member 18. A half-cut step is performed in which the blade 28 cuts along the planned division line 8 and a cutting groove 29 having a depth at which the electrode 12 is not fully cut is formed on the surface of the package substrate 2 along the planned division line 8. In the enlarged cross-sectional view obtained by enlarging a part of FIG. 5, a cutting groove 29 formed by half-cutting the electrode 12 is formed.

Actually, since the electrode 12 is formed in a discrete manner along the scheduled division line 8, the peripheral portion of the electrode 12 after the half-cut step is in the state as shown in FIGS. 6 (A) and 6 (B). It becomes.

In the half-cut step of the present embodiment, the electrode 12 is cut together with the covering member 18, and the electrode 12 is half-cut. Therefore, since the volume for removing the covering member 18 is larger than the volume for removing the electrode 12 in the half-cut step, it is possible to suppress the generation of burrs when cutting the electrode 12.

Further, since the abrasive grains are contained in the adhesive layer 22 of the covering member 18, the cutting blade 28 can be sharpened by performing the half-cut step, and the clogging of the cutting blade 28 can be removed. The effect is also exhibited.

When the half-cut step is performed, the adhesion of the cutting chips of the metal electrode 12 adhering to the cutting blade 28 is suppressed by cutting the covering member 18.

After performing the half-cut step, the covering member peeling step of peeling the covering member 18 cut in the half-cut step from the surface of the package substrate 2 is carried out. Preferably, in the covering member peeling step, as shown in FIG. 7A, an external stimulus 30 such as ultraviolet irradiation or heating is applied to the covering member 18 to reduce the adhesive strength of the pressure-sensitive adhesive layer 22 of the covering member 18. Then, as shown in FIG. 7B, the covering member 18 is peeled off to expose the electrodes 12 on both sides of the scheduled division line 8.

After the covering member 18 is peeled off, as shown in FIG. 8, the center of the cutting groove 29 is cut with the second cutting blade 28A thinner than the first cutting blade 28, and the package substrate 2 is cut into individual package device chips 32. Perform a split step to split into.

FIG. 9 shows a perspective view of the package device chip 32 manufactured by the processing method of the present embodiment. As is clear from FIG. 9, since the two-step cutting was performed, a step is formed in each electrode 12.

2 Package board 4 Metal frame (lead frame)
6a, 6b, 6c Device area 8 Scheduled division line 10 Device chip mounting part 12 Electrode 14 Mold resin layer 16 Frame unit 18 Coating member 22 Adhesive layer 28, 28A Cutting blade 29 Cutting groove 30 External stimulation 32 Package device chip (QFN) )

Claims (1)

A metal frame in which a plurality of electrodes are formed along a plurality of planned division lines formed in a grid pattern for partitioning an area on which a device chip is mounted, and a plurality of devices mounted in the area of the metal frame. A method for processing a package substrate including a chip and a molded resin layer laminated on the back surface side of the metal frame so as to cover the plurality of device chips.
A covering member mounting step in which a covering member containing no abrasive grains is laid on the surface of the package substrate on which the electrodes are exposed along the planned division line, and the covering member is mounted on at least the plurality of scheduled division lines.
The package substrate on which the covering member is mounted is cut from above the covering member with a first cutting blade, and a cutting groove along the planned division line at a depth at which the electrode is not fully cut is formed in the package substrate. Half-cut steps formed on the surface and
A covering member peeling step for peeling the covering member cut in the half-cut step from the surface of the package substrate, and a covering member peeling step.
After performing the covering member peeling step, the center of the cutting groove is cut along the planned division line with a second cutting blade thinner than the first cutting blade, and the package substrate is cut into individual package device chips. With a split step, which splits into
In the covering member mounting step, a liquid resin mixed with heat-expandable microspheres that fire when heated to a predetermined temperature or higher is laid on the surface of the package substrate, and heating to a temperature lower than the predetermined temperature, ultraviolet irradiation, or time elapsed. To cure the liquid resin to form the covering member.
In the covering member peeling step, the covering member is heated to a predetermined temperature or higher to shoot the heat-expandable microspheres to form irregularities on the cured liquid resin, and the covering member made of the liquid resin is peeled off. After facilitating, the covering member is peeled off,
In the half-cut step, the cutting blade is sharpened by cutting the covering member, clogging of the cutting blade due to cutting chips of the electrode is suppressed, and burrs on the electrode are generated by cutting the covering member. A method for processing a package substrate, which is characterized by suppressing .

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