KR100696414B1 - Sintered material for capillary used in wire bonding and method for manufacturing the same - Google Patents

Abstract

In the present invention, silicon nitride, α-alumina, and yttria are used as sintering aids, and polyethylene glycol is further added as a binder of the sintering powders to prepare a sintering agent, followed by drying, grinding / filtering, two-stage compression molding, and debinding. The present invention relates to a wire bonding capillary sintered body manufactured through a treatment, sintering, and etching process, and a method for manufacturing the same, and according to the present invention, the physical properties such as toughness, strength, hardness, wear resistance, and impact resistance are excellent.

Capillary, Wire Bonding, Impact Resistance, Wear Resistance, Silicon Nitride

Description

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

1 is a process chart showing a manufacturing process of the silicon nitride capillary sintered body according to the present invention.

2A to 2G illustrate examples of the compression molding process of FIG. 1.

3 is a photograph of the surface of the silicon nitride capillary sintered body according to the present invention before the etching step is performed.

4 is a surface photograph after an etching step of the silicon nitride capillary sintered body according to the present invention.

Figure 5 is a graph comparing the fracture toughness and hardness of the silicon nitride capillary sintered body and the conventional wire bonding capillary sintered body according to the present invention.

Figure 6 is a graph comparing the breakdown (Broken Test) of the silicon nitride capillary sintered body and the conventional wire bonding capillary sintered body according to the present invention.

7 is a graph comparing the lifespan of the silicon nitride capillary sintered body and the conventional capillary sintered body for wire bonding according to the present invention.

Explanation of symbols on the main parts of the drawings

30. Compression Molding 32. Through Hole

34. Upper core mold 36. Lower core mold

38. Tip 44. Capillary molded body

The present invention relates to a capillary sintered body for wire bonding and a method for manufacturing the same, and more particularly, silicon nitride (Si ₃ N ₄ ) having improved impact resistance and abrasion resistance of the capillary tip. It relates to a capillary sintered body using the powder) and a method of manufacturing the same.

In general, in the manufacturing process of a semiconductor device, a wire bonding device may be formed by connecting an external connection passage of a device such as a lead frame, a ceramic circuit board, a printed circuit board, or an input / output pad or die of a semiconductor chip with aluminum, gold, or copper. It is used to connect.

As the capillary used as described above, the tip portion where the ball is formed is brought into contact with the lead of the semiconductor input / output pad and the lead frame during the first bonding and the second bonding, and the capillary is placed in a high voltage discharge state. The tip of the filler is required for impact resistance and abrasion resistance.

Conventionally, capillary has been used alumina (Al ₂ O ₃ ) sintered body having a purity of 99.99 or more. The pure alumina sintered body as described above has a relatively high strength material and economical efficiency, but has low fracture toughness, so that the reliability is inferior, and the strength drops sharply at high temperature, and its durability is not good. In addition, the relatively short lifespan has contributed to the cost increase in the manufacture of semiconductor devices.

In order to solve the above problems, capillary is currently used as a main material of alumina and zirconia (ZrO ₂ ) composite material, by adding zirconia to suppress grain growth of alumina and improve toughness, but irregular internal pores exist When the wire bonding using ultrasonic wave is less than 80 ㎛ of the fine pitch tip size (Fine Pitch Tip Size) due to internal pores, wire bonder (Wire Bonder) parameters, that is, the ultrasonic transfer is not made well, many defects are generated have.

Thus, artificial ruby capillary with high material hardness was developed to compensate for the above problem, and the service life of the alumina-zirconia composite capillary was increased by 2-5 times, but the impact resistance is weak, so it is easy to handle or use the product. A problem broke.

Impact resistance and wear resistance are related to the pore content of the raw material of the capillary sintered body and the partial structure corresponding to the capillary tip. Therefore, when the pore content is large, the structure of the capillary sintered body is not dense, so that impact resistance and abrasion resistance are insufficient, and secondary bonding defects occur during wire bonding.

In addition, no matter how good the material is, when the capillary is formed, the molding pressure is low and the pore content of the molded body is high, and when the density and relative density of the sintered body are low, the wear resistance and impact resistance are low, so the tip is easily broken or worn, and thus the wire bonding process When the wire bonding using the ultrasonic wave becomes difficult to perform, or the ultrasonic wave is blocked by internal pores, it is difficult to accurately form the ball at the end of the wire inserted in the capillary.

Moreover, the problem of increasing the density of the sintered body is influenced not only by the molding pressure but also by the mixing ratio of the binder for making the bonding between the powder particles uniform during compression molding.

That is, when a large amount of binder is added, many pores are generated in the sintered body after the sintering process, whereas when the amount of the binder is insufficient, core pins are broken or difficult to remove the molded body during compression molding.

Accordingly, the present inventors have completed the present invention by checking the wear resistance and impact resistance effects of the silicon nitride sintered body according to the present invention while studying the mixing ratio and compression molding pressure conditions of the ideal binder.

Therefore, the present invention has been made to solve the above problems and at the same time to minimize the breakage and wear of the capillary tip, the main object of the present invention is to maximize the impact resistance and wear resistance of the capillary tip wire bonding capillary To provide a sintered body.

In addition, another object of the present invention to provide a method for producing a capillary sintered body for wire bonding maximizing the impact resistance and wear resistance of the capillary tip.

In order to achieve the above object, the present invention provides silicon nitride (Si ₃ N ₄ ) 88 to 95 wt%, α-alumina (Al ₂ O ₃ ) 2 to 5 wt% and yttria (Y ₂ O ₃ ) 4 to 7 wt % Is used as a sintering aid, and as the binder of the sintering aid powder, polyethylene glycol having a molecular weight of 500 to 600 is further added in the range of 5 to 20 wt% to form a sintered body, and the sintered body has a size of 45 to 150 µm. A capillary sintered body for wire bonding processed into granulated powder is provided.
Moreover, this invention provides the manufacturing method of the capillary sinter for wire bonding which uses a silicon nitride, (alpha)-alumina, and yttria as a baking aid.
Specifically, the present invention,
88 to 95 wt% of silicon nitride (Si ₃ N ₄ ), 2 to 5 wt% of α-alumina (Al ₂ O ₃ ), and 4 to 7 wt% of yttria (Y ₂ O ₃ ), as a firing aid, and the firing aid A powder mixing step of further adding polyethylene glycol having a molecular weight of 500 to 600 in the range of 5 to 20 wt% as a binder of the powder, and mixing 99.5% methanol as a dispersion solvent to produce a silicon nitride slurry;
A drying step of drying the silicon nitride slurry at a low temperature of 50 ° C;
A pulverization / filtering process of pulverizing the dried silicon nitride slurry (molded product) and de-sphering the pulverized powder into non-spherical granulated powder having a size of 5 to 150 μm through at least two sieves having different mesh sizes;
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 having a conical tip having the same size and shape as the first core mold A compression molding step of forming a capillary molded body by inserting and compressing the non-spherical silicon nitride powder into the through hole using a two-core mold;
Debinding step of maintaining the binder contained in the molded body in the hydrogen (H ₂ ) atmosphere furnace at a rate of 0.5 ℃ / min to 600 ℃ by maintaining for about 50 hours and then removed from the sintered body;
After the debinding process, the molded body was subjected to a pressure of 2 MPa at 1,820 ° C. at a room temperature rate of 5 ° C./minute in a gas pressure sintering furnace in a nitrogen (N ₂ ) atmosphere for 1 hour for 30 minutes to 3 hours. After primary sintering. A sintering step of performing two-stage gas pressure sintering at a same temperature at a pressure of 10 MPa for 30 minutes to 3 hours; And
It provides a method for producing a capillary sintered body for wire bonding comprising an etching step of immersing the sintered body in sodium hydroxide melted in an alumina crucible for 1 to 5 minutes.

The above and other objects of the present invention will be more clearly understood by the following detailed description based on the accompanying drawings.

Figure 1 shows the manufacturing process of the present invention, the process for producing a capillary sintered body according to the present invention is illustrated in Figure 1, powder mixing (S1) → drying (S2) → grinding / manure (S3) ) → compression molding (S4) → debinding treatment (S5) → sintering (GPS) (S6) → etching (S7) process.

The powder mixing process (S1) is 88 to 95 wt% of silicon nitride (Si ₃ N ₄ ), 2 to 5 wt% of α-alumina (Al ₂ O ₃ ) and 4 to 7 wt% of yttria (Y ₂ O ₃ ). Is a firing aid, and 5 to 20 wt% of polyethylene glycol having a molecular weight of 400 to 600 as a binder and methanol having a purity of 99.5% are added and mixed with a solvent.

The silicon nitride slurry prepared through the powder mixing process (S1) is poured into an evaporating dish and dried through a drying process (S2) for 140 to 160 hours at a low temperature (50 ° C.) on a hot plate to induce alumina induction of the dried silicon nitride mass. Crushing / filtering process (S3), which is pulverized using a standard mesh # 100 (150 μm), followed by a standard mesh # 325 (45 μm), which is then spheroidized to a particle size having a distribution of 45 to 150 μm. Will go through.

Subsequently, the silicon nitride powder, which has undergone the crushing / filtering process (S3), is put into the capillary molding die 30 and compression molded to manufacture the capillary molded body 44. An example of the method of manufacturing a capillary molded object is shown in detail in FIGS. 2A-2G.

As shown in Figure 2a, the compression molding die 30 composed of cemented carbide is made of a cylindrical having a through hole 32 therein. In addition, 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 are made of cemented carbide.

The capillary molded body according to the present invention is produced by a two-stage compression molding process (S4). A detailed explanation follows below with reference to the drawings.

As shown in FIG. 2B, 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.

As shown in FIG. 2C, the non-spherized silicon nitride powder 40 is inserted into the hole 32 in which the lower portion is blocked through the crushing / filtering process S3. The tip 38 of the upper core mold 34 is introduced into the inserted silicon nitride non-spherical powder 40, and then the lower core mold 36 is moved upward by about 5 mm so that the non-spherized silicon nitride powder 40 ) Is first compressed. At this time, the lower core mold 36 is moved upward in the range in which the tip 38 of the upper core mold is not broken to compress the silicon nitride powder 40 so that the portion compressed by the lower core mold 36 has a higher molding density. There is an effect to reduce the internal pores in the.

As shown in FIG. 2D, the lower core mold 36 is returned to the position before the primary compression, and then the upper core mold 34 is moved downward as shown in FIG. 2E to the first compressed silicon nitride powder. 40 is compressed twice to form a molded body 44.

Then, when the final compression molding is finished, as shown in FIG. 2F, the lower core mold 36 is completely pulled downward, and the upper core mold 34 is continuously moved downward to move the compression molded body 44 out of the cylindrical mold 30. Discharged. At this time, the jig 46 fixes the upper core mold 34 to suppress expansion of the upper core mold 34. Thus, the tip 38 of the upper core mold and the molded body 44 are separated to smooth the conical hole inner surface of the molded body 44.

Next, as in FIG. 2G, the upper core mold 34 is moved to an initial position and separated from the molded body 44.

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.

Debinding treatment step (S5) is a process of burning the polyethylene glycol used as a binder at a low temperature before the final sintering, the process is heated to 600 ℃ at a normal temperature of 0.5 ℃ / min in a hydrogen (H ₂ ) atmosphere furnace After maintaining for about 50 hours to completely remove the polyethylene glycol from the sintered body.

The sintering process (S6) undergoes two stages of gas pressure sintering using a gas pressure sintering furnace, ie 2 MPa at 1,820 ° C at a rate of 0.5 ° C / min for the first time in a nitrogen (N ₂ ) atmosphere furnace. After sintering for a predetermined time by applying a pressure of, the process is sintered and cooled for a predetermined time at a pressure of 10 MPa at the same temperature.

In the above, the sintering time is preferably performed in the range of 30 minutes to 3 hours.

Typically, the silicon nitride which has undergone gas pressure sintering in a gas pressure sintering furnace has a sharp growth of silicon (Si) particles on the inner and outer surfaces of the product, as shown in FIG. 3. If you touch the gold wire passing through the inner hole, this may cause a scratch on the gold wire may be a major cause of failure.

Therefore, an etching step (S7) is required to smooth the inner surface of the silicon nitride sintered body. After adding sodium hydroxide (NaOH) to the alumina crucible and heating it with a hot plate to melt sodium hydroxide, an etching process of immersing the silicon nitride sintered body in the molten sodium hydroxide for about 1 to 5 minutes is performed, as shown in FIG. The inner surface of the sintered compact which forms the shape becomes smooth.

The invention will be more clearly understood by the following examples, and it is understood that the claims of the present invention are not limited or reduced by the following examples.

Example 1 Powder Preparation

Α-type silicon nitride (Si ₃ N ₄ , 99.99%, SN E-10, Ube Co.) with an average particle diameter of 0.3 μm and α-type alumina (Al ₂ O ₃ , 99.99%, AKP-50, Sumitomo Co.) and yttria (Y ₂ O ₃ , 99.9%, Hermann Co.) with an average particle diameter of 0.4 μm are used as starting materials, and a silicon nitride ball (Φ5.0) is placed in a 2 L polyurethane container with a container volume. After filling with 364 g of silicon nitride, 12 g of alumina, and 24 g of yttria, add 60 g of polyethylene glycol (# 400) and 800 g of methyl alcohol (99.5%) for dispersing as a binder and lubricant. Milling produced a silicon nitride slurry.

In order to prevent hard drying by rapid drying, the silicon nitride slurry prepared above was poured into an evaporating dish, dried at 50 ° C. on a hot plate for 150 hours at low temperature, and dried to a soft mass.

The softly dried silicon nitride mass was pulverized with alumina induction and sifted using standard mesh # 100 (150 μm), filtered through the above process first, and then again filtered to standard mesh # 325 (45 μm). A non-spherical powder was prepared with a particle size having a distribution of 45 to 150 μm.

Example 2: Compression Molding

The powder prepared above was inserted into a hydraulic press equipment, and a silicon nitride capillary molded body was manufactured through a two-step compression molding process.

Example 3: Debinding and Gas Pressure Sintering

In the process of carrying out the polyethylene glycol used as a binder in Example 1 to burn at a low temperature before the final sintering, after heating up to 600 ℃ at a rate of 0.5 ℃ / min in a furnace of hydrogen atmosphere and maintained for 50 hours from the sintered body Polyethylene glycol was completely removed.

Final sintering is a two-stage gas pressure sintering using a gas pressure sintering furnace, that is, the molded product prepared above is laminated on a silicon nitride plate with string grooves at intervals of 3 mm, covered with a cover and charged into a furnace in a nitrogen atmosphere. Sintering was carried out at 1820 ° C. at a pressure of 2 MPa at a heating rate of 0.5 ° C./min at 1 ° C., and nitrogen gas pressure was applied at 10 MPa at the same temperature to maintain 1 hour.

Example 4: Etching

The alumina crucible was placed on a hot plate, sodium hydroxide was added, and the mixture was heated and melted at 250 ° C. to immerse the prepared sintered body for 3 minutes, and the inside of the hole of the sintered body was etched smoothly.

Table 1 and FIG. 5 show the results of comparing the fracture toughness and hardness as physical property test results of the silicon nitride sintered body manufactured through the above example and the capillary sintered body for wire bonding.

As can be seen from Table 1 and Figure 5, the silicon nitride sintered body according to the present invention, it was confirmed that the fracture toughness and hardness is excellent compared to the conventional wire bonding capillary sintered body.

TABLE 1

Sintered body type Fracture Toughness (MPa) Hardness (kgf / mm2) Al ₂ O ₃ + ZrO ₂ 4.13 1850 Ruby 3.52 2100 Si ₃ N ₄ 5.92 1870

In addition, the results of comparing the breakdown test (Broken Test) and the service life of the silicon nitride sintered body and the conventional wire bonding capillary sintered body according to the present invention are shown in Figs.

As can be seen in Figures 6 to 7, the silicon nitride sintered body according to the present invention was confirmed to exhibit an excellent effect in impact resistance and life compared to the conventional capillary sintered body for the wire bond.

As described above, the silicon nitride capillary according to the present invention has an effect of satisfying physical properties such as toughness, strength, hardness, wear resistance, and impact resistance required for the capillary for wire bonding.

In addition, the polyethylene glycol may serve as a lubricant when removing the molded body in addition to the binder, thereby preventing the upper core pin mold from being stuck or broken in the molded structure.

Furthermore, by removing the growth of silicon particles generated inside and outside the sintered body, which was a problem during the sintering of silicon nitride, through the etching process using sodium hydroxide, it is possible to replace the ruby capillary, which has a long life but is easily broken and difficult to apply to fine pitch tips.

Claims (14)

88 to 95 wt% of silicon nitride (Si ₃ N ₄ ), 2 to 5 wt% of α-alumina (Al ₂ O ₃ ), and 4 to 7 wt% of yttria (Y ₂ O ₃ ), as a firing aid, and the firing aid As a binder of the powder, polyethylene glycol having a molecular weight of 500 to 600 was further added in the range of 5 to 20 wt% to form a sintered body, and the wire bonding capillary processed into the non-spherical granulated powder having a size of 45 to 150 μm. Li sintered body. In the manufacturing method of the capillary for wire bonding, 88 to 95 wt% of silicon nitride (Si ₃ N ₄ ), 2 to 5 wt% of α-alumina (Al ₂ O ₃ ), and 4 to 7 wt% of yttria (Y ₂ O ₃ ), as a firing aid, and the firing aid A powder mixing step of further adding polyethylene glycol having a molecular weight of 500 to 600 in the range of 5 to 20 wt% as a binder of the powder, and mixing 99.5% methanol as a dispersion solvent to produce a silicon nitride slurry; A drying step of drying the silicon nitride slurry at a low temperature of 50 ° C; A pulverization / filtering process of pulverizing the dried silicon nitride slurry (molded product) and de-sphering the pulverized powder into non-spherical granulated powder having a size of 5 to 150 μm through at least two sieves having different mesh sizes; 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 having a conical tip having the same size and shape as the first core mold A compression molding step of forming a capillary molded body by inserting and compressing the non-spherical silicon nitride powder into the through hole using a two-core mold; Debinding step of maintaining the binder contained in the molded body in the hydrogen (H ₂ ) atmosphere furnace at a rate of 0.5 ℃ / min to 600 ℃ by maintaining for about 50 hours and then removed from the sintered body; After the debinding process, the molded body was subjected to a pressure of 2 MPa at 1,820 ° C. at a room temperature rate of 5 ° C./minute in a gas pressure sintering furnace in a nitrogen (N ₂ ) atmosphere for 1 hour for 30 minutes to 3 hours. After primary sintering. A sintering step of performing two-stage gas pressure sintering at a same temperature at a pressure of 10 MPa for 30 minutes to 3 hours; And An etching step of immersing the sintered body in sodium hydroxide melted in an alumina crucible for 1 to 5 minutes; manufacturing method of a capillary sintered body for wire bonding comprising a. delete delete delete delete delete delete delete delete delete delete delete delete

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