KR100413034B1 - Sintered material for multi color capillary used in wire bonding and method for manufacturing the same - Google Patents

Abstract

Powders that can be colored in a mixed powder of α-alumina (Al ₂ O ₃ ) powder and zirconia-yttria (ZrO ₂ -Y ₂ O ₃ ) powder, for example, Fe ₂ O ₃ , CuO, CoO, 0.5 to 20 wt% of Co ₃ O ₄ , MnO ₂ , Cr ₂ O ₃ and V ₂ O ₅ are mixed with this mixed powder and subjected to compression / molding and sintering steps, depending on the diameter of the wire received. Disclosed are a multicolor capillary sintered body capable of producing color and a method of manufacturing the same.

Description

Sintered material for multi color capillary used in wire bonding and method for manufacturing the same}

The present invention relates to a capillary sintered body of a wire bonding system, and more particularly, to a multicolored capillary sintered body and a method for producing the same, which can easily distinguish capillaries accommodating different wire diameters.

In the semiconductor package manufacturing process, the wire bonding device is used to connect external connection passages of packages such as lead frames, ceramic circuit boards, and printed circuit boards, and input / output pads or dies of semiconductor chips using aluminum, gold, or copper. Used. Capillary is essential in the wire bonding process using a wire bonding apparatus.

In Fig. 1, the bonding state between the chip and the lead frame is shown. On the surface of the pad 1a of the semiconductor chip 1 made of aluminum and the lead frame 2 made of alloy material exposed to the air, the wires 3 may be thermocompressed, thermosonic, or ultrasonic. It is wire bonded to the lead frame 2.

On the other hand, the capillary 10 is composed of a cylindrical body 7 and the fine holes 9 provided therein, as shown in FIG. In the microhole 9, a ball bonding wire 6 having a thickness of 1.0 to 1.3 mils (1 mil is 1/1000 inch) is accommodated. The microhole 9 has a conical shape in which its diameter decreases toward the lower end, and the lower diameter H of the microhole 9 has a size corresponding to the size of the wire 6. The lower end of the capillary 10 is the chamber 15, and is inclined at a predetermined angle in consideration of the bonding interval and the shape and size of the metal wire after bonding. The diameter CD of the chamber is related to the size of the ball 5.

Looking at the bonding process with reference to Figures 2a, 2b and 3, the capillary 10 forms a ball at the end of the wire 6 through a high voltage discharge. This ball is contacted / pressurized to the pad 1a of the chip under the control of the wire bonding device, ultrasonic energy is transferred to the lower end of the capillary 10, and when the heat is applied to the pad 1a, the ball is pressed to the pad 1 Bonded by car A detail of the primary bonded state is shown in FIG. 3. That is, after the circuit element is formed on the substrate 11, the planarization film 12 such as BPSG is covered and the pad 13 of the chip is completed. Next, the passivation film 14 is formed on the pad 13 with a silicon nitride film or the like. And the bonding window 8 which has the width W1 is formed. The width of the bonding window 8 is larger than the diameter CD of the chamber 15 and the ball 5 pressed for primary bonding is filled in the bonding window 8.

Thereafter, the capillary 10 is pulled out of the primary bond to form a wire locus 3 of constant trajectory, which is connected to the lead of the lead frame by the second stitch bond.

As described above, the size of the ball 5 during primary bonding is related to the width of the contact window 8, and the width of the contact window 8 is related to the dimension of the pad 1a of the chip. In addition, the size of the ball 5 is affected by the degree of inclination of the chamber 15. The size of the ball 5 is also related to the diameter of the wire 6 and the bottom diameter H of the fine holes 9.

On the other hand, in the case where the pads of the chips are closely arranged, the distance between the pads and the pads is closer to each other than the small arrangement area, so that the diameter of the bonding wire used should be relatively small. That is, the size of the lower end diameter (H) of the fine holes 9 of the capillary 10 used for bonding should be small. Accordingly, when the arrangement of the pads or the frame leads is small, wire bonding is performed with wires of about 1.3 mils, and wires of 1.0 mils are used for wire bonding of chips having a relatively dense arrangement. However, since it is impossible to visually distinguish the hole diameters of 1.0 mils and 1.3 mils, the capillary is managed by separately indicating the size of the bottom diameter of the fine holes in the capillary storage container.

Therefore, the wire bonding process facilitator proceeds by believing only the matters indicated on the container, so the screening operation of the capillary is important. Incorrect screening or incorrectly marked screening can lead to poor wire bonding. That is, there was no safety management system in the classification and storage of capillaries. Therefore, there is a need for a capillary differentiation method for accommodating wires which are selectively used according to dense or small arrangements of chip pads or lead frames.

Accordingly, the technical problem to be achieved by the present invention is to provide a multi-color capillary sintered body and a method of manufacturing the same that can easily distinguish / manage the capillary according to the diameter of the wire to be accommodated in view of the above-described problems. .

1 is a perspective view illustrating a bonding state of a chip and a lead frame.

2A and 2B are longitudinal cross-sectional views illustrating a bonding process between a chip and a lead frame.

FIG. 3 is a detailed view illustrating the primary bonded pad of FIG. 2B.

Figure 4 is a flow chart showing the manufacturing process of the multi-color capillary sintered body according to the present invention.

5A through 5G are diagrams illustrating an example of the compression molding process of FIG. 4.

6 is a temperature graph illustrating an example of the first sintering process of FIG. 4.

In order to achieve the technical problem to be achieved by the present invention, the color of the body of the capillary was changed according to the diameter of the wire that can be accommodated.

Specifically, 0.5 to 20wt% of a powder capable of coloring the mixed powder in a mixed powder composed of α-alumina (Al ₂ O ₃ ) powder and zirconia-yttria (ZrO ₂ -Y ₂ O ₃ ) powder. Mix As the color powder, any one of Fe ₂ O ₃ , CuO, CoO, Co ₃ O ₄ , MnO ₂ , Cr ₂ O _3, and V ₂ O ₅ may be used. In addition, the container containing the mixed powder and the color powder may include a liquid binder that induces bonding between the α-alumina powder and the zirconia powder particles to form an alumina-zirconia color composite. The composite is converted into a multicolor capillary sintered body having a fracture toughness of 5.2 to 5.4 MPam ^ 0.5 and a Vickers hardness of 1970 to 2010 Mpa through drying, grinding, compression / molding and sintering. The particle size of the alumina powder and the zirconia-yttria powder is 0.2 to 0.8 mu m, and the particle size of the color powder is about 0.5 to 0.8 mu m. And as a binder, it is preferable that the liquid binder contains 5-20 wt% of polyethylene glycol with respect to the mixed powder, and it can use especially the molecular weight 400-600.

Looking at the specific method for forming the alumina-zirconia color sintered body described above, first to 0.5 to 20wt% color powder and α-alumina powder and zirconia in the mixed powder consisting of α-alumina powder and zirconia-yttria powder Liquid binders that induce binding between the powder particles are mixed and ground to form an alumina-zirconia color composite. Dry the complex. The dried complex is ground and spheroidized. A cylindrical capillary forming mold having a through hole of a predetermined diameter therein; a cylindrical first core mold having a diameter equal to the diameter of the through hole; and a first tip having the same size and shape as the first core mold and having a conical tip. A capillary molded body is formed by inserting a spherical composite into a through hole and compressing it using a 2 core mold. The capillary molded body is placed in a sintering furnace and heated to sinter.

For preferred compression / molding, a core mold with a conical tip is placed on top of the cylindrical mold for sintering the capillary and the lower core mold closes the bottom of the through hole of the cylindrical mold. The spheroidized composite is inserted into the closed through hole. The tip of the upper core mold is introduced into the inserted composite, and then the lower core mold is moved upwards to first compress the spheroidized composite. Return the lower core mold to the position before the first compression. The upper core mold is moved downward, and the primary compressed composite is secondary compressed to form a shaped body.

The sintering step preferably includes a degreasing heat treatment step for degreasing the binder, a preliminary heat treatment step to stabilize particle growth energy of the capillary sintered body, and a main heat treatment step for full grain growth of the molded body. After the sintering step, the second sintering step of placing the sintered body in a high-temperature compression furnace and maintaining the predetermined time (for example, 1500 ° C. and about 60 minutes at 1000 bar) at 1000-1500 ° C. and 500-1500 bar is further performed. You can also carry out.

On the other hand, the amount of the color powder and the liquid binder based only on pure α-alumina (Al ₂ O ₃ ) powder instead of the mixed powder of α-alumina (Al ₂ O ₃ ) powder and zirconia-yttria powder described above. May be determined.

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

4 is a flowchart showing a step of manufacturing a multicolor capillary sintered body according to the present invention. In a mixing vessel, α-alumina (Al ₂ O ₃ ) powder having a purity of 99.99% or more and a particle size of about 0.2 μm to 0.8 μm and zirconia-ytria (ZrO ₂ -Y ₂ O ₃ having a particle size of 0.2 μm to 0.8 μm A mixed powder of powder and 0.5wt% to 20wt% of color powder are mixed with each other to form an alumina-zirconia color mixture (S1). As the color powder raw materials, blue, blue green, and blue violet capillary sintered bodies are produced using Fe ₂ O ₃ , CuO, CoO, and Co ₃ O ₄ . And a color powder raw materials, using MnO _2, Cr ₂ O ₃ and V ₂ O _5, respectively, making the capillary sintered brown, pink and yellow.

Here, as an example of the mixed powder, the zirconia-yttria powder may be mixed with 70-95 wt% of the alumina powder. And, it can be made only of pure alumina powder, in this case, the alumina-zirconia color mixture is formed by mixing 0.5wt% to 20wt% color powder with respect to pure alumina powder.

5-20 wt% of liquid polyethylene glycol, alumina ball (Φ5mm) was added to 1/3 of the mixing vessel, and 100 wt% of the mixed powder was added to a dispersed organic solvent such as ethanol or methanol. A slurry form alumina-zirconia color composite. Preferably, the liquid polyethylene glycol uses a molecular weight of 400 to 600. Since the organic solvent and the binder are materials burned during sintering and the color powder does not affect the physical properties of the capillary sintered body, the amount of these additives is determined based on the mixed powder. If the amount of binder added is large, in addition to the role of the binder, it may be pushed out of the tissue of the molded body during subsequent compression / molding, and thus may also serve as a lubricant when removing the molded body, thereby further increasing the compression / molding ratio. .

Next, the alumina-zirconia color composite is placed in a rotary grinder and mixed and ground by rotating at a speed of 80 rpm for about 24 hours. Subsequently, the composite is poured into a predetermined sieve to filter the alumina balls from the composite, and the remaining slurry is dried at 50 to 70 ° C. on a hot plate to evaporate the organic solvent (S2).

The dried alumina-zirconia color composite mass was put into alumina-induced powder and pulverized, and then, the sieve having a mesh size of 200 µm was used to flow the powder into the molding die in a subsequent compression molding step, and the compression transmission between the particles was uniform. In order to make, the alumina-zirconia color composite mass is finely spheroidized (S3).

Subsequently, the alumina-zirconia color composite pulverized and spheroidized is put into a capillary forming mold (30 in FIG. 5A) and compressed / molded to produce a capillary molded body (44 in FIG. 5E) (S4). One example of the process for making the capillary molded body is shown in detail in FIGS. 5A-5G.

As shown in FIG. 5A, the compression molding mold 30 composed of cemented carbide is cylindrical having a through hole 32 therein. And in order to form a molded object, the upper core mold 34 and the lower core mold 36 are prepared. The upper core mold 34 and the lower core mold 36 have the same size and are aligned with the through hole 32 of the cylindrical mold 30. The upper core mold 34 has a conical tip 38. The upper core mold 34 and the lower core mold 36 consist of cemented carbide.

In FIG. 5B, the lower core mold 36 is inserted into the hole 32 to block the lower portion of the through hole 32 of the cylindrical mold. Then, the pulverized / spheroidized powder 40 is inserted into the hole 32 in which the lower portion is blocked. The upper core mold 34 is inserted into the hole 32 by about 1 mm. And as shown in FIG. 5C, the lower core mold 36 is moved slightly upward. That is, a range in which the molding density of the portion in which the lower core mold 36 is compressed by the lower core mold becomes high so that the tip 38 of the upper core mold 34 does not break in the subsequent final compression process, for example, 5 mm. Move upwards to slightly compress the milled / sphered powder. Reference numeral 42 denotes a powder in a compressed state compared to the powder indicated by 40. By this preliminary compression process, the forming density of the tip 38 portion of the upper core mold 34 is increased, so that the internal pores in this portion can be reduced.

Then, as shown in Fig. 5d, the lower core mold 36 compressed by about 5 mm is returned to the pre-compression position. In FIG. 5E, the upper core mold 34 finally compresses the pre-compressed crushed / sphered powder to the point controlled by the compression stop device to form the molded body 44. Subsequently, as shown in FIG. 5F, when the final compression is completed, the lower core mold 36 moves to the position of the standby state of FIG. 5A, and the upper core mold 34 moves the compression / molding body 44 into the cylindrical mold 30. ), The molded body 44 expands outside the cylindrical mold 30. At this time, the jig 46 catches the upper core mold 34 to suppress expansion of the upper core mold. Accordingly, the tip 38 and the molded body 44 of the upper core mold 34 are separated to smooth the inner surface of the conical hole of the molded body 44. Next, as shown in FIG. 5G, when the upper core mold 34 is returned to the position in the atmosphere of FIG. 5A, the molded body falls downward.

In the above-described method, the upper core mold 34 and the lower core mold 36 are disposed so that the fine holes of the capillary sintered body are directed upward, but the positions of the upper core mold 34 and the lower core mold 36 are changed. After the microholes of the capillary sintered body are directed downward, the compression / molding process may be performed.

Returning to FIG. 2 again, after the forming step, the capillary molded body (44 in FIG. 5G) is placed in a high temperature sintering furnace and subjected to primary sintering. By primary sintering, the temperature of the capillary molded body 44 rises to about 1550-1650 degreeC. Primary sintering includes at least a degreasing step of the binder and a substantial sintering step. In addition, the binder degreasing step and the temperature difference according to the difference in heat transfer time between the sintering furnace and the capillary molded body and the temperature difference between the molded bodies disposed at upper, lower and intermediate positions in the laminate of the capillary molded body are considered. Between the substantially sintering steps, it may further comprise a pre-sintering step to stabilize the grain growth of the molded body. A graph showing the first sintering process including the presintering step is shown in FIG. 6.

6, in detail, the temperature of the sintering furnace in which the capillary molded body is provided therein is elevated to 1 ° C. per minute at room temperature, and then raised to 300 ° C. to 500 ° C. By maintaining the temperature of the sintering furnace at about 300 to 500 ° C. for about 30 to 50 hours, the binder contained in the molded body is degreased, and the temperature difference between the sintering furnace and the molded body and the temperature of the upper, lower and middle parts of the molded body are reduced. Make it uniform.

In two steps, the temperature of the sintering furnace is raised from 300 to 500 ° C., from 1000 to 1200 ° C., at 5 ° C. per minute, and held at about 1 hour at 1000 to 1200 ° C., thereby preliminary operation of the molded particles Stabilize growth energy. The two stages bring the temperature of the capillary molded body closer to the temperature level of the sintering furnace, and the capillary molded body stack remains at a uniform temperature level as a whole.

The third step is a full-scale sintering step, which controls the growth of the particles of the molded body but grows in a large scale, thereby densifying the structure of the sintered body, and rapidly raises the sintering furnace to about 1550-1650 ° C. at 10 ° C. per minute. Since the particle growth energy of the capillary molded body is stabilized in step 2, even if the temperature is rapidly increased in this step, the uneven growth of the particle of the molded body can be suppressed. However, when the molded particles become huge, the density of the particles may be lowered and the tissue may not be dense, so that the retention time of the three steps may be adjusted in consideration of this. Next, the sintered compact is gradually cooled.

By the pre-sintering step, the time taken for the temperature of the capillary molded body 44 to rise to the temperature level of the sintering furnace is shortened, and the top, bottom and middle of the capillary molded body laminate at the same sintering furnace temperature are The temperature difference between the moldings located is reduced. As a result, the molded articles in the upper, lower and intermediate positions of the capillary molded laminate were all grown into uniform structures. Therefore, the structure of the capillary sintered body becomes dense and the surface of the capillary sintered body becomes smooth so that foreign substances do not easily adhere to the capillary during wire bonding, and defects do not occur during stitching bonding. This will be longer.

Next, returning to FIG. 4 again, after the first sintering is completed, it is possible to selectively perform the second sintering (S6).

The first sintered sintered body is placed in a ceramic container and placed in a hot isostatic press at a temperature of about 1000-1500 ° C. and 500-1500 bar for a predetermined time, for example, about 1500 ° C. and 100 bar at 60 ° C. It is kept for a minute to densify the structure by removing residual fine pores inside the sintered body. The holding time here varies with pressure and temperature. Thus, the wear resistance and impact resistance of the sintered body are further improved.

Thereafter, the color capillary sintered body is processed to produce an alumina zirconia color composite capillary for wire bonding.

The capillary sintered body having different colors is completed according to the kind of color powder added to the mixture of alumina powder and zirconia-yttria powder, and the change of physical properties is hardly occurred as compared with the case where the color powder is not added.

After completing the above-described three-step primary sintering of the composite containing only 75 wt% of aluminum powder and 25 wt% of zirconia-yttria powder, the Vickers hardness and fracture toughness were measured, and 1970 (MPa) and 5.4 (MPam ^1/2 ), respectively. When 75 wt% of alumina powder and 25 wt% of zirconia-yttria powder were added with 5 wt% of Co ₃ O ₄ , the Vickers hardness and fracture toughness of the sintered body after the same sintering step were 1980 (MPa) and 5.5 ( MPam ^1/2 ). That is, the addition of the color powder does not substantially change the physical properties of the alumina-zirconia composite sintered body.

Without changing the physical properties of the alumina-zirconia composite sintered body, it is possible to impart a variety of colors to the alumina-zirconia composite, which was conventionally produced only in white. The capillary using the sintered body is also colored, and the capillary color can be changed according to the lower diameter of the microhole of the capillary, the inclination angle of the chamber, and the width of the chamber. Accordingly, the wire bonding process facilitator can easily distinguish and use a capillary suitable for the working environment, and thus, there is an advantage of reducing the wire bonding process defect due to the incorrect selection of the capillary.

Claims (18)

Drying, pulverizing, and pulverizing an alumina-colored composite comprising a base powder comprising at least α-alumina powder and a liquid binder which induces a bond between about 0.5 to 20 wt% of the color powder to the base powder and the base powder particles It is formed by performing a first sintering process including a second step of compression / molding and a heat treatment step of 1000-1200 ° C. for grain growth of the powders, and a second sintering process of 1000-1500 ° C. and 500-1500 bar. Colorful capillary sintered body. According to claim 1, wherein the base powder includes a zirconia-yttria powder in addition to the α-alumina powder, the alumina-colored composite is a multi-color capillary consisting of the α-alumina powder, zirconia powder and the color powder Sintered body. The multicolored capillary formed by drying, pulverizing, compressing / molding and sintering the alumina-zirconia color composite has a fracture toughness of 5.2 to 5.4 MPam ^ 0.5 and a Vickers hardness of 1970 to 2010 Mpa. Multicolored capillary sintered body. The multicolored capillary sintered body according to claim 1, wherein the color powder is any one of Fe ₂ O ₃ , CuO, CoO, Co ₃ O ₄ , MnO ₂ , Cr ₂ O _3, and V ₂ O ₅ . The multicolored capillary sintered compact according to claim 2, wherein the alumina powder and the zirconia-yttria powder have a particle size of 0.2 to 0.8 mu m. 2. The multicolored capillary sintered body according to claim 1, wherein the color powder has a particle size of about 0.8 mu m. The multicolored capillary sintered body according to claim 1, wherein the liquid binder is polyethylene glycol. The multicolored capillary sintered body according to claim 7, wherein the polyethylene glycol is contained in an amount of 5 to 20wt% based on the base powder. The multicolored capillary sintered body according to claim 7, wherein the polyethylene glycol has a molecular weight of 400 to 600. 0.5 to 20 wt% of the color powder with respect to the base powder and a liquid binder for inducing bonding between the particles of the base powder are mixed with the base powder including at least α-alumina powder, and ground to form an alumina-colored composite. Steps, Drying the complex, Pulverizing the dried composite to spheroid, A cylindrical capillary forming mold having a through hole of a predetermined diameter therein; a cylindrical first core mold having a diameter equal to the diameter of the through hole; and a first tip having the same size and shape as the first core mold and having a conical tip. Forming a capillary molded body by inserting and compressing the spherical composite into the through hole using a 2 core mold; And inserting the capillary molded body into a sintering furnace, followed by heating to sinter the multicolored capillary molded body. The multi-color capillary of claim 10, wherein the basic powder includes zirconia-yttria powder together with the α-alumina powder, and the alumina-colored composite is composed of the α-alumina powder, zirconia powder and the color powder. Method for producing a sintered body. The method of claim 10, wherein the color powder is any one of Fe ₂ O ₃ , CuO, CoO, Co ₃ O ₄ , MnO ₂ , Cr ₂ O _3, and V ₂ O ₅ . The method for producing a multicolored capillary sintered body according to claim 8, wherein the liquid binder is polyethylene glycol. The method of claim 13, wherein the polyethylene glycol is contained in an amount of 5 to 20 wt% based on the base powder. 15. The method for producing a multicolored capillary sintered body according to claim 14, wherein said polyethylene glycol has a molecular weight of 400 to 600. The method of claim 10, wherein the sintering step includes a degreasing heat treatment step for degreasing the binder, a preliminary heat treatment step to stabilize particle growth energy of the capillary sintered body, and a main heat treatment step for full grain growth of the molded body. The manufacturing method of the multicolored capillary sintered compact. 11. The method of claim 10, After the sintering step of the capillary sintered body further comprises a second sintering step of putting the sintered body in a high-temperature compression furnace and maintained for a predetermined time at 1000-1500 ℃, 500-1500 bar Manufacturing method. The method of claim 10, wherein the forming of the capillary molded body, Preparing the cylindrical mold, the lower core mold and the upper core mold, Blocking the lower end of the through hole of the cylindrical mold with the lower core mold; Inserting the spherical composite into the through hole closed at one end; Allowing the tip of the upper core mold to flow into the inserted composite, and then moving the lower core mold upward to first compress the spheroidized composite, Returning the lower core mold to a position prior to first compression and Moving the upper core mold downward to compress the primary compacted composite to form a compact to form a compact.