KR20050082018A - Flip chip bonding method using screen printing method - Google Patents

Abstract

Disclosed is a flip chip connection method using a screen printing technique. In the flip chip connection method using an anisotropic conductive adhesive or non-conductive adhesive, the present invention provides a method of preparing a substrate having a plurality of conductive pads for delivering electrical signals, and aligning a screen having a plurality of holes on the substrate. Applying an anisotropic conductive adhesive or non-conductive adhesive on a substrate on which the screen is aligned; removing the screen; and a semiconductor chip having a plurality of conductive bumps capable of transmitting and receiving an electrical signal with the conductive pad. Adhering to the substrate. In the flip chip connection method using the screen printing method according to the present invention, the adhesive can be applied only to a specific specific area, thereby reducing the consumption of the adhesive. Because it can be manufactured by using a flip chip bonding method using a simple and low-cost process, it is also very useful for improving the size and performance of the product.

Description

Flip chip bonding method using screen printing method

The present invention relates to a flip chip connection method for electrically connecting a semiconductor chip and a package substrate using an anisotropic conductive adhesive or nonconductive adhesive. It is related with the method of apply | coating and flip-chip connection.

Flip chip connection is a form of chip scale package (CSP), and refers to a method of manufacturing a semiconductor by directly connecting conductive pads without using a lead frame between the semiconductor chip and the package substrate. The flip chip connection is very small to reduce the phase difference of the electric signal flowing in the chip because the size of the packaged chip is much smaller than the size of the chip manufactured by the existing wire connection and the path difference of each transmission line is small. It is very useful as a connection method and will be widely used.

Flip chip connection method using the anisotropic conductive adhesive or non-conductive adhesive of the technical field of the present invention is integrated by bonding a semiconductor chip and a package substrate using an anisotropic conductive adhesive having an electrical conductivity in the thickness direction or a non-conductive adhesive having no conductivity. It is. This flip chip connection method is electrically connected between the bumps of the semiconductor chip and the pads of the package substrate, and the bumps and bumps of the semiconductor substrate and the pads and pads of the package substrate are electrically insulated. It is widely used in semiconductors, and is applied to DRAM, memory, microprocessor, ASIC, and other semiconductors.

The present invention is a flip chip connecting method for applying anisotropic conductive adhesive or non-conductive adhesive with a dispenser on a package substrate and then applying the adhesive only to a desired portion on the package substrate using a kind of screen. The invention relates to a method for bonding a semiconductor chip.

1 is a diagram illustrating a flip chip connection method using an adhesive generally used in the past and now, in particular a flip chip connection method using an anisotropic conductive adhesive.

The semiconductor chip 110 is briefly illustrated on the package substrate 100, and the alignment key 130 for alignment with the plurality of pads 120 is provided on the package substrate 100, respectively. It is formed in the same arrangement as.

Lattice dotted lines indicate that each individual chip is completed by cutting after bonding.

The flip chip connection using this method is completed by applying an anisotropic conductive adhesive on the package substrate and then heating and pressing each semiconductor chip 110 and cutting along the dotted line.

FIG. 2 is a view for explaining the cutting of the unit chip part of FIG. 1 briefly and in more detail.

An anisotropic conductive adhesive 150 is applied onto the package substrate using a dispenser 140. Thereafter, the semiconductor chip 110 is bonded through a heat compression process.

3 illustrates a state in which a semiconductor device is completed after the process illustrated in FIG. 2.

4 is a cross-sectional view taken along the dotted line A-B of FIG. 3. In order to show the three pads, the shape is cut at an oblique angle.

Cross-sections of the pads 160 of the semiconductor chip 115 aligned with the pads 125 formed on the package substrate 105 are shown, and the configuration of the anisotropic conductive adhesive 150 is also illustrated. The anisotropic conductive adhesive includes a plurality of conductive balls 155 and non-conductive particles 156. The semiconductor chip 115 and the package substrate 105 are bonded to each other with an anisotropic conductive adhesive 150, and at the same time, the pads 160 of the semiconductor chips 115 and the pads 125 of the package substrate 105 are aligned with each other and are conductive. It electrically conducts with each other through the ball 155.

The flip chip connection method using the anisotropic conductive adhesive as described above has a great advantage in that the flip chip connection can be completed in a relatively simple process with stable reliability and is a key technology to be widely used for manufacturing each semiconductor electronic component.

However, the coating method through the dispenser is inferior in coating uniformity, the application process time is longer than necessary, and the adhesive is applied as a whole. Therefore, the SAW filter or the center portion of the circuit of the semiconductor chip must be exposed to the air (air cavity). There is a disadvantage that it can not be used to manufacture electronic components such as an image sensor that does not come in contact with the package substrate.

5 is a view briefly showing a longitudinal section of a conventional SAW filter.

It shows that the SAW filter chip is built in the package 200, such as a ceramic material surrounding the outside, and the pads 220 are electrically connected to each other by the metal wires 230. The reason for manufacturing the SAW filter in this shape is that the surface of the SAW filter chip 210 must be exposed to air. Due to this problem, the existing flip chip connection method cannot manufacture a device that requires a space to be in contact with air, such as a SAW filter.

FIG. 6 illustrates a previous step for connecting a device having a special shape in which a space 330 in which an adhesive should not be applied to the package substrate 300 such as an image sensor is formed by a flip chip method.

As shown in the figure, in the case of a device that must have a space on the package substrate, since it is difficult to connect the flip chip, it was generally connected by wire bonding method. However, in the case of the wire bonding method, the distance between the semiconductor chip and the substrate is different depending on the wire bonding, except that the device size is larger than the flip chip connection method. There are several fatal drawbacks. This problem is a serious problem for semiconductor devices operating in the ultra-high frequency region, and thus requires a very difficult and cumbersome design technique that requires the same path to the semiconductor chip itself. Therefore, if the device of such a special shape is connected by a flip chip connection method using an adhesive, it will bring about an excellent effect not only in manufacturing but also in the operation of the device.

As shown in the drawing, pads 320 are formed on the package substrate 300 having a space 330 and are aligned with each pad 320 so that the semiconductor chip 310 is bonded. do. However, since there is a space 330 in the package substrate 300, it is a problem to be solved that a flip chip connection method using an existing adhesive, which also applies an adhesive to the connection region as a whole, cannot be applied.

As described above, the flip-chip connection method using the conventional adhesive that applies the adhesive to the entire adhesive area has a disadvantage in that it consumes a lot of adhesive and cannot be applied to the manufacture of a special device having a space on a SAW filter or a package substrate. .

An object of the present invention is to reduce the consumption of the adhesive and to reduce the process time to apply the adhesive by applying and bonding the adhesive only to the desired portion, in particular, by making a portion that can be in contact with the air on the semiconductor chip, including SAW filter, etc. Various other devices are manufactured by a flip chip connection method using an adhesive.

In order to solve the above technical problem, the present invention provides a method of preparing a substrate having a plurality of conductive pads for transmitting electrical signals in a flip chip connecting method using an anisotropic conductive adhesive or a non-conductive adhesive, and a plurality of substrates on the substrate. Aligning a screen with holes, applying an anisotropic conductive adhesive or nonconductive adhesive on the substrate on which the screen is aligned, removing the screen, and a plurality of conductive materials capable of transmitting and receiving electrical signals with the conductive pads. Bonding a semiconductor chip having bumps to the substrate.

The screen is any one of a metal sheet, metal mesh or silk mesh and the substrate is a PCB substrate or an organic insulating substrate.

Hereinafter, the present invention will be described in detail with the drawings.

FIG. 7 illustrates a flip chip connection method using an adhesive incorporating a screen 430 printing technique according to a first embodiment of the present invention.

There is a screen 430 formed to have holes 440 to form and align pads 410 for transmitting electrical signals to the PCB or the organic insulating substrate 400. The screen 430 is in close contact with the substrate 400 in the process of applying the adhesive on the package substrate during the flip chip connection process using the adhesive is in progress. That is, the adhesive applied by the dispenser 450 is applied only to a desired portion through the hole 440 formed in the screen 430 of the present invention. After the process of adhering the semiconductor chip 110, the external shape is not different from the device bonded by the flip chip connection method according to the prior art.

The screen according to the present invention is made by cutting, etching, or patterning holes in a metal sheet made of a material such as Ni using a laser or silk mesh. Or it is produced by preventing the adhesive from passing through the metal mesh (metal mesh), except the hole in the emulsion.

Among the adhesives used in the present invention, particularly conductive anisotropic conductive adhesives include conductive particles and non-conductive particles that transmit electrical signals. The conductive particles may be metal particles or particles coated with metal or coated with a non-conductive material, and then particles that exhibit conductivity by peeling off the surface during the flip chip connection process may be selectively used. Non-conductive particles mainly use inorganic particles as non-conductive particles such as silica. As shown in the figure, non-conductive particles have a smaller diameter than conductive particles.

Non-conductive adhesives do not include conductive particles and non-conductive particles because they do not have to be conductive unlike anisotropic conductive adhesives.

FIG. 8 illustrates a longitudinal cross-section of a device completed by a flip chip connection method using an anisotropic conductive adhesive, in particular, as compared with FIG. 4 according to the prior art.

Since the screen according to the present invention is used, the anisotropic conductive adhesive 540 is applied to and adhered to each bump 520 and the pad 530 so that a longitudinal cross section as shown in the figure is important. That space 550 exists. Thus, devices such as SAW filters can also be manufactured by the method according to the invention.

FIG. 9 is a cross-sectional view taken along the line C-D of FIG. 6 when a device having a special shape such as the image sensor shown in FIG. 6 is manufactured by the flip chip connection method using the anisotropic conductive adhesive according to the present invention.

Since it does not apply the adhesive as a whole, even if there is an empty space on the package substrate, it is possible to apply a flip chip connection method using an anisotropic conductive adhesive by applying the adhesive only to the desired portion.

10 shows a second embodiment of a screen according to the invention.

Although it is possible to apply the adhesive by making a space in the shape of a pad as in the left part of the drawing, if the adhesive force is a problem due to the small amount of adhesive, the space can be applied except for the area where the adhesive should not be applied as shown on the right side of the drawing. Increase Although shown in the drawings simply, it is obvious that it can be applied in various shapes as needed.

FIG. 11 is a diagram illustrating a flip chip connecting method according to the present invention using a non-conductive adhesive 560.

Non-conductive adhesives do not contain conductive balls and non-conductive particles that must carry electrical signals. Therefore, when the flip chip connection is implemented using a non-conductive adhesive, the semiconductor chip and the pads of the package substrate must directly contact each other to transmit and receive electrical signals.

The flip chip connection method using the screen printing technique according to the present invention can apply the adhesive only to a desired specific area, thereby reducing the consumption of the adhesive, shortening the adhesive application process time, and in particular, a SAW filter requiring space between pads in contact. B. Special devices such as image sensors can be manufactured by the flip chip bonding method using adhesives, which makes it possible to manufacture products in a simple and low-cost process as well as to improve the size and performance of the products.

1 is a view for explaining a flip chip connection method using an anisotropic conductive adhesive according to the prior art.

2 is a view for explaining the connection method of FIG. 1 in more detail.

3 is a semiconductor chip and a package substrate connected by the flip chip connection method using an anisotropic conductive adhesive according to the prior art.

4 is a longitudinal sectional view taken along the line A-B of FIG. 3;

5 is a longitudinal cross-sectional view for explaining the interior of a typical SAW filter.

6 is a view for explaining a flip chip connection method of a special electronic device having a space on a package substrate such as an image sensor.

7 is a view for explaining a flip chip connection method using an anisotropic conductive adhesive according to the present invention.

8 is a longitudinal sectional view of a semiconductor element connected by the present invention;

Fig. 9 is a longitudinal sectional view showing a state in which a special electronic device having a space on a package substrate such as an image sensor is flip-chip connected by the present invention.

10 is a screen used in the flip chip connection method using the anisotropic conductive adhesive according to the second embodiment of the present invention.

11 is a longitudinal cross-sectional view of a semiconductor device connected by a flip chip connection method using a screen printing technique according to the present invention using a non-conductive adhesive.

<Explanation of symbols for the main parts of the drawings>

100, 105, 300, and 500: package substrate 110, 115, 310, and 510: semiconductor chip

120, 125, 320, 530: Pad 130 on package substrate: Alignment key

140, 450: dispenser 150, 540: adhesive 155: conductive particles 156: non-conductive particles

160, 325, 520: bump of semiconductor chip

200: ceramic package 210: SAW filter chip 220: pad of SAW filter chip

230: bonding wire 330; Package board space

400: package substrate 410: pad on the package substrate

430: screen 440: hole 550: space 560: non-conductive adhesive

Claims (3)

In the flip chip connection method using an anisotropic conductive adhesive or non-conductive adhesive, Preparing a substrate having a plurality of conductive pads for delivering electrical vibrations; Aligning a screen with a plurality of holes on the substrate; Applying an anisotropic conductive adhesive or nonconductive adhesive on the substrate on which the screen is aligned; Removing the screen; And And attaching a semiconductor chip having a plurality of conductive bumps capable of exchanging electrical signals with the conductive pads with the substrate. The method of claim 1, wherein the screen is any one of a metal sheet, a metal mesh, or a silk mesh. 2. The method of claim 1, wherein the substrate is a PCB substrate or an organic insulating substrate.