JP7680932B2 - Processing method - Google Patents

Description

The present invention relates to a method for processing a wiring board on which device chips are arranged on the front and back surfaces.

Wafer with multiple devices such as ICs and LSIs formed on its surface, partitioned by planned division lines, is divided into individual device chips by a dicing machine or laser processing machine, and these are mounted on wiring boards for use in electrical devices such as mobile phones and personal computers.

Generally, wiring boards are formed into a predetermined shape corresponding to the configuration of electrical devices such as mobile phones and personal computers, and are then assembled into the electrical devices (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 06-163634

However, when device chips are disposed on the front and back surfaces of a wiring board, when the front and back surfaces of the wiring board are inverted in order to process the front and back surfaces of the wiring board, support parts for supporting the wiring board may be formed on the wiring board. This poses the problem that processing must be performed to remove such unnecessary parts without contaminating the wiring board and device chips before assembly into the electrical device, which is unbearable.

The present invention has been made in consideration of the above facts, and its main technical objective is to provide a processing method that can perform desired processing on a wiring board without contaminating the wiring board and device chips.

In order to solve the above-mentioned main technical problem, the present invention provides a processing method for a wiring board having device chips disposed on the front and back surfaces, comprising a sealing step of wrapping the wiring board in a thermocompression sheet, heating it, removing air, and sealing the wiring board with the thermocompression sheet, a substrate fixing step of fixing the front side or back side of the wiring board sealed with the thermocompression sheet to a substrate, and a processing step of holding the substrate on a chuck table of a processing device and performing the desired processing on the wiring board by a processing means constituting the processing device.

The processing means is preferably a cutting means equipped with a rotatable cutting blade having a cutting edge on its outer periphery, and is used to cut off unnecessary portions of the wiring board.

The processing method of the present invention is a method for processing a wiring board having device chips on the front and back sides, and includes a sealing step of wrapping the wiring board in a thermocompression sheet, heating it, removing air, and sealing the wiring board with the thermocompression sheet, a substrate fixing step of fixing the front side or back side of the wiring board sealed with the thermocompression sheet to a substrate, and a processing step of holding the substrate on a chuck table of a processing device and performing a desired processing on the wiring board by a processing means constituting the processing device. Therefore, it is possible to perform a desired processing on the wiring board without contaminating the wiring board and the device chips, and it is possible to remove unnecessary parts from the wiring board, for example. This solves the problem that it is too cumbersome to perform the desired processing without contaminating the wiring board and the device chips before assembling the wiring board in a specified electrical device.

1 is a perspective view of a wiring board processed by a processing method according to an embodiment of the present invention; 2 is a perspective view showing a state in which the wiring board shown in FIG. 1 is wrapped with a thermocompression sheet; FIG. 3 is a perspective view showing a mode in which the outer peripheral region of the thermocompression sheet shown in FIG. 2 is thermocompression-bonded. FIG. 4 is a perspective view showing a state in which the central region of the thermocompression sheet shown in FIG. 3 is thermocompression-bonded. FIG. 5 is a perspective view showing a mode of separating an excess area of the thermocompression sheet shown in FIG. 4. FIG. 1 is a perspective view showing an embodiment of a substrate fixing step for fixing a wiring board to a substrate; FIG. 1A is a perspective view showing an embodiment of a processing step for performing a desired processing on a wiring board, and FIG. 1B is a perspective view of the wiring board after the processing method is completed and the thermocompression sheet has been peeled off.

The following describes in detail an embodiment of a processing method based on the present invention, with reference to the attached drawings.

1 shows a perspective view of a wiring board 10 processed by the processing method of this embodiment. A plurality of device chips 11, 12, 13, and 14 are arranged on the front surface 10a side of the wiring board 10. Although not shown, a plurality of device chips are also arranged on the back surface 10b side of the wiring board 10. As shown in FIG. 1, the wiring board 10 is a substantially rectangular board, and support pieces 15 and 16 that are held when forming a device on the wiring board 10 are formed on the opposing short sides 10c and 10d. The support pieces 15 and 16 are unnecessary parts when the wiring board 10 is assembled into a specific electrical device, and are parts that are processed and cut by the processing method implemented by this embodiment. In this embodiment, the support pieces 15 and 16 are formed only on the short sides 10c and 10d, but they may be formed on the opposing long sides 10e and 10f.

The processing method of this embodiment, which is carried out to prepare the wiring board 10 having the device chips arranged on the front surface 10a and back surface 10b described above so that it can be assembled into a specified electrical device, is described below.

When carrying out the processing method of this embodiment, once the unprocessed wiring substrate 10 described above is prepared, the sealing process described below is carried out.

When carrying out the sealing process, as shown in the upper part of FIG. 2, thermocompression sheets 22, 24 of a size capable of wrapping the wiring board 10 are prepared. The thermocompression sheets 22, 24 are sheets that have no adhesive applied to their surfaces and exhibit adhesive strength when heated, and are preferably selected from polyolefin-based sheets or polyester-based sheets. When selecting from polyolefin-based sheets, it is preferable to select from, for example, polyethylene sheets, polypropylene sheets, and polystyrene sheets, and when selecting from polyester-based sheets, it is preferable to select from polyethylene terephthalate sheets and polyethylene naphthalate sheets. The temperature at which the thermocompression sheets 22, 24 are heated varies depending on the material of the sheet, and by heating to a temperature close to the melting temperature of each sheet, adhesive strength can be exhibited more effectively.

In this embodiment, a case will be described in which polyethylene sheets are selected as the thermocompression sheets 22, 24. As can be seen from the figure, the thermocompression sheets 22, 24 are selected to have a size that can encase the entire wiring board 10 including the support pieces 15, 16 and ensure an excess area on the periphery for bonding the thermocompression sheets 22, 24 together. Note that the thermocompression sheets of the present invention are not limited to two sheets, and may be, for example, a single thermocompression sheet with an area that can encase the front surface 10a and back surface 10b of the wiring board 10, which is folded and used.

Once the thermocompression sheets 22 and 24 described above are prepared, place the back surface 10b of the wiring board 10 facing the center of one of the thermocompression sheets 24 as shown in the figure, and cover the front surface 10a of the wiring board 10 with the other thermocompression sheet 22, so that the entire wiring board 10 is wrapped in the thermocompression sheets 22 and 24 as shown in the lower part of Figure 2.

Next, the heating roller 30 shown in FIG. 3 is prepared as a means for performing the thermocompression bonding. The heating roller 30 is equipped with a heating means (not shown) for heating the surface 32 of the heating roller 30 inside, which heats the thermocompression sheets 22, 24 to a predetermined temperature, for example, 120°C to 140°C, at which the thermocompression sheets 22, 24 exert their adhesive force. The surface 32 is also coated with a fluororesin so that the thermocompression sheets 22, 24 do not adhere to the heating roller 30 even if the thermocompression sheets 22, 24 exert their adhesive force due to the heating. Once the heating roller 30 is prepared, the heating roller 30 is heated to the predetermined temperature and rotated in the direction shown by the arrow, and the outer peripheral region 26 of the thermocompression sheets 22, 24 surrounding the wiring board 10 is pressed to thermocompress the thermocompression sheets 22 and 24, thereby thermocompressing the thermocompression sheets 22 and 24 together. At this time, as shown in FIG. 3, the central region 27 where the wiring board 10 is placed and the suction region 28, which is part of the outer peripheral region 26, are not subjected to thermal compression bonding by the heating roller 30.

4, a suction pump (not shown) is connected to the suction port 28a of the suction area 28, and a negative pressure V is generated at the suction port 28a to remove air from the central area 27 that encases the wiring board 10. At the same time, hot air H is supplied from above the thermocompression sheet 22 and below the thermocompression sheet 24 to heat the thermocompression sheets 22 and 24 to the above-mentioned predetermined temperature (120°C to 140°C). As a result, the thermocompression sheets 22 and 24 are thermocompressed tightly to the front surface 10a and back surface 10b of the wiring board 10 in the central area 27 that encases the wiring board 10. At the same time that the thermocompression of the central area 27 is completed, the air intake port 28a is closed and the suction area 28 is also thermocompressed. As a result, the wiring board 10 is sealed and integrated by the thermocompression sheets 22 and 24, the device chips formed on the front surface 10a and back surface 10b of the wiring board 10 are lifted up, and the sealing process of this embodiment is completed as shown in the lower part of Figure 4.

When carrying out the above-mentioned sealing process, the specific form in which the thermocompression sheets 22, 24 are thermocompressed is not limited to the above-mentioned embodiment. For example, instead of the above-mentioned heating roller 30, a flat heating and pressing means corresponding to the outer peripheral region 26 surrounding the wiring board 10 may be prepared, and the heating and pressing means may be pressed against the above-mentioned outer peripheral excess region 26 to perform thermocompression. In addition, the heating method using the above-mentioned hot air H is not limited to this, and the thermocompression sheets 22, 24 may be heated, for example, by irradiating them with infrared rays.

After the above-mentioned sealing process is performed to form the wiring board 10 sealed by the thermocompression sheets 22 and 24, the substrate fixing process described below is performed. In this embodiment, the surplus area separation process described below is performed before the substrate fixing process is performed. The surplus area separation process is performed to obtain a shape more suitable for performing the substrate fixing process described below, and can be omitted as appropriate depending on the size of the wiring board 10, the size of the thermocompression sheets 22 and 24, etc.

As shown in Figure 5, the excess area separation process involves placing the wiring board 10, which has been sealed and integrated by the thermocompression sheets 22, 24, on the upper surface Ta of an appropriate table T, and using an appropriate separation means 40 to form a separation groove 100 along the periphery of the wiring board 10 and remove the excess area 29, and forming it into a rectangular shape smaller than the thermocompression sheets 22, 24 before separation as shown in the lower part of Figure 5. Even in the rectangular shape from which the excess area 29 has been removed, the wiring board 10 is entirely wrapped by the thermocompression sheets 22, 24 from which the excess area 29 has been removed, and the integrated state by thermocompression is maintained.

After the above-mentioned excess area separation process is performed, the substrate 50 shown in FIG. 6 is prepared. The substrate 50 is, for example, a circular plate-like member having rigidity, and is formed of glass, stainless steel, or the like. When fixing the wiring board 10 sealed by the thermocompression sheets 22, 24 to the substrate 50, for example, liquid resin P is first dripped onto the center of the substrate 50. After the liquid resin P is dripped, the wiring board 10 sealed by the thermocompression sheets 22, 24 is placed on the substrate 50 with either the front surface 10a or the back surface 10b facing upward. In this embodiment, the front surface 10a is placed on the liquid resin P with the back surface 10b facing downward. The liquid resin P hardens over time, and the wiring board 10 is fixed on the substrate 50 as shown in the lower part of FIG. 6, completing the substrate fixing process of this embodiment. By interposing the liquid resin P between the substrate 50 and the wiring board 10, the unevenness caused by the device chips on the back surface 10b of the wiring board 10 is absorbed, and the wiring board 10 is stably fixed on the substrate 50. In the above embodiment, the liquid resin P is used to fix the wiring board 10 sealed by the thermocompression sheets 22, 24 to the substrate 50, but there is no particular limitation as long as it is a material that can absorb the unevenness caused by the device chips arranged on the wiring board 10 and has the function of fixing the wiring board 10 to the substrate 50. For example, wax that melts when heated and solidifies when cooled, or flexible double-sided tape can be used.

After the substrate fixing process described above is performed, the substrate 50 with the wiring board 10 fixed thereto is transferred to a cutting device 60 (only a part of which is shown) which is a processing device of this embodiment shown in FIG. 7(a) and the substrate 50 with the wiring board 10 fixed thereto is held on the holding surface 62a of a chuck table 62. Next, a cutting means 63 which is provided with a rotatable cutting blade 64 having a cutting edge on the outer periphery and which is arranged as a processing means of the cutting device 60 and cuts off unnecessary parts of the wiring board is positioned on a straight line along the short side 10c of the wiring board 10. Next, the cutting blade 64 is rotated and cuts downward while being processed along the short side 10c, cutting off the support piece 15 which is an unnecessary part when the wiring board 10 is assembled to a predetermined electrical device. Following this, a similar cutting process is performed to cut off the support piece 16 which is also an unnecessary part from the wiring board 10 along the short side 10d, completing the processing process of this embodiment and the processing method of this embodiment.

After carrying out the above-mentioned processing steps, the thermocompression sheets 22, 24 remaining on the front surface 10a and back surface 10b of the wiring board 10 can be peeled off at any time before the wiring board 10 is assembled into a predetermined electrical device, to produce the state shown in FIG. 7(b). When performing this peeling, the thermocompression sheets 22, 24 are cooled or heated to make them easier to peel off. As described above, no adhesive or the like is applied to the thermocompression sheets 22, 24, and even if the thermocompression sheets 22, 24 are peeled off, no adhesive or the like remains on the wiring board 10, and no deterioration in quality is caused.

According to the processing method of the embodiment described above, the wiring board 10 and the device chips formed on the front surface 10a and back surface 10b of the wiring board 10 are protected by the thermocompression sheets 22, 24, and the wiring board 10 sealed and integrated by the thermocompression sheets 22, 24 is firmly fixed to the substrate 50 and made in a state that is easy to process. Therefore, it is possible to remove unnecessary parts (support pieces 15, 16 in the above embodiment) from the wiring board 10 by processing with the cutting device 60 without contaminating the wiring board 10 and the device chips with processing debris, etc. Therefore, the problem of the troublesome work of performing the desired processing on the wiring board 10 without contaminating the wiring board 10 and the device chips before assembling the wiring board 10 to a specified electrical device is solved.

In the above embodiment, an example was shown in which the processing step is performed by cutting processing to remove unnecessary portions of the wiring board 10 using a cutting device 60 equipped with a cutting blade 64, but the present invention is not limited to this. For example, the processing step performed by the present invention may be laser processing to irradiate a laser beam using a laser processing device and remove unnecessary portions of the wiring board 10.

The desired processing performed by the processing step of the present invention is not limited to the processing of removing the support pieces 15, 16 as described above, but may be, for example, a drilling process to form a hole in the wiring board 10. Even when such a drilling process is performed, the above-mentioned sealing process and substrate fixing process are performed, so that the wiring board 10 and the device chip are not contaminated, and the problem of the work being too cumbersome when performing the desired processing on the wiring board 10 is solved.

10: Wiring board 10a: Surface 10b: Back surface 10c, 10d: Short sides 10e, 10f: Long sides 11 to 14: Device chips 15, 16: Support pieces 22, 24: Thermocompression sheet 26: Outer peripheral region 27: Central region 28: Suction region 28a: Suction port 30: Heating roller 32: Surface 40: Separating means 50: Substrate 60: Cutting device 62: Chuck table 62a: Holding surface 64: Cutting blade 100: Cutting groove P: Liquid resin

Claims (2)

A method for processing a wiring substrate having device chips disposed on a front surface and a back surface, comprising the steps of:
a sealing process in which the wiring board is wrapped in a thermocompression sheet, heated, and air is removed, and the wiring board is sealed with the thermocompression sheet;
a substrate fixing step of fixing the front side or the back side of the wiring board sealed with the thermocompression sheet to a substrate;
a processing step of holding the substrate on a chuck table of a processing device and subjecting the wiring board to a desired processing by a processing means constituting the processing device;
A processing method comprising the steps of: The processing method according to claim 1, wherein the processing means is a cutting means equipped with a rotatable cutting blade having a cutting edge on its outer periphery, and cuts off unnecessary portions of the wiring board.

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