JPH081372A - Composite soldering material and its manufacture - Google Patents

Abstract

PURPOSE:To provide a composite soldering material excellent in the ductility at high temperature and excellent in the cold machinability as the soldering material to join the parts of a semi-conductor device accompanying the heat generation. CONSTITUTION:The soldering material having the composition consisting of, by weight, 5-15% Sb, 2-15% Ag, and the balance substantially Sn with inevitable impurities is melted in the inert atmosphere, and cast to manufacture the ingot. This ingot is extruded, and rolled or cold machined by the drawing to manufacture the tape or wire of the prescribed shape and dimension.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite solder material and a method for manufacturing the same, and more particularly, to a composite solder material for joining components used at high temperatures, and in particular, semiconductor device components used at high temperatures due to heat generation. TECHNICAL FIELD The present invention relates to a composite solder material suitable for joining solder and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a composite solder in which powder is mixed in solder has been known as a connecting material for fixing a semiconductor chip to a substrate. Japanese Patent Application Laid-Open No. 2-151389 discloses that
There is disclosed a solder cream in which a fine conductive material is mixed with solder in order to prevent cohesive separation of solder when connecting a chip component to a circuit board. Japanese Unexamined Patent Publication No. 63-58945 discloses a solder bump forming method in which molten solder in which solid particles are dispersed is brought into contact with each other in order to improve creep life and fatigue life of solder when connecting a semiconductor chip and a lead frame. Has been done. On the other hand, when fixing a semiconductor chip to a substrate, a normal alloy solder that does not mix powder is processed into a wire or tape shape and provided for semiconductor mounting, and is used for connecting the semiconductor chip and the substrate while fusing to a predetermined amount. . However, in this case, when a predetermined amount of wire or tape is supplied between the chip and the substrate and solidified, the levelness of the chip is poor.

Here, maintaining the levelness of the chip by keeping the thickness of the molten solder after solidification constant means that a predetermined heat cycle property is maintained at the connection portion of the chip, and the semiconductor changes due to temperature change due to heat generation of the semiconductor. This is useful in preventing chip peeling and accompanying poor conduction. As a countermeasure, when connecting the semiconductor chip and the substrate, in order to keep the semiconductor chip horizontal, it is possible to use wire or tape-shaped composite solder that mixes powder into the solder and performs cold processing to finish it to the required shape and dimensions. Is being considered. When such a composite solder material is used for connecting a semiconductor chip and a substrate, there is a problem that the solder material is cracked due to heat generation of the semiconductor chip. Therefore, there is a demand for a composite solder material that uses a solder material that can withstand high temperatures and can be cold worked.

Generally, high temperature solder has a solidus temperature of Pb-
A material having a eutectic temperature of Sn (183 ° C.) or higher. Usually, Sn is the main component, and Pb, In, Ag, Sb,
It contains Cu, Ni and the like. Among them, those containing Sn as the main component and Sb are preferable as the high temperature solder because the high temperature strength and the creep characteristics are improved. On the other hand, when a semiconductor element is bonded onto a lead frame by using a solder containing Sn as a main component and containing only Sb, Sn-Sb is generated due to heat generation of the semiconductor chip.
There is a problem that cracks are likely to occur in the solder member. Conventionally, attempts have been made to contain Sn, Sb-based solders containing Ni, Cu, Bi, etc., but the effect is not sufficient for preventing cracks at high temperatures due to heat generation of semiconductor chips, and cold working Has the drawback of becoming difficult. Therefore, in Sn-Sb type solder, a solder material that is effective in preventing cracks at high temperatures and has good cold workability has not been obtained, so it is limited to applications such as ribbon solder and cream solder by direct rapid cooling of molten metal. However, its excellent high temperature strength and creep properties have not been fully utilized.

Here, the crack prevention at high temperature will be described in detail. Considering from the environment where the semiconductor device is practically exposed,
It is required to have excellent ductility at a temperature of 170 ° C. In addition, when describing cold workability in detail, segregation is likely to occur during casting when performing cold working through melting and casting processes to adjust to a predetermined shape and size, which also contributes to the fragility of the material. There is a phenomenon that hot working becomes difficult. Japanese Unexamined Patent Publication No. 61-86091 discloses a ribbon-like solder which is obtained by adding Ni and P to Sn-Sb-based solder to directly solidify it in a ribbon-like shape from a melt having improved high temperature bonding strength at 150 ° C. are doing. However, the environment to which semiconductor devices are exposed in practice is more severe, and the higher temperature (17
It is insufficient as a solder material having excellent ductility at 0 ° C. Further, since it contains Ni and P, it has a drawback that segregation during casting is likely to occur for cold working, which makes cold working difficult.

Japanese Unexamined Patent Publication No. 5-502286 discloses Sn-A.
Compared with the case where the composition of the g-Cu system contains Bi or Pb, it is -5.
Disclosed is a solder cream that provides a solder excellent in a thermal shock test at 5 ° C to 125 ° C. An example in which 2% by weight of Sb is added is shown. However, even this composition system is insufficient as a solder material having excellent ductility at a higher temperature of 170 ° C. Further, since it contains Cu, it has a drawback that segregation during casting is apt to occur during cold working, which makes cold working difficult.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a composite solder material which can simultaneously achieve the problems described in (1) and (2) below. (1) A solder material having a high ductility measured at 170 ° C. as a solder material effective for preventing cracks at a high temperature due to heat generation of a semiconductor chip. (2) In order to hold the semiconductor chip horizontally on the substrate,
It is a composite solder material and has excellent cold workability to finish it into the specified shape and dimensions.

[0008]

As a result of intensive studies by the present inventor, it was thought that the ductility decreases because the strength tends to increase as Sb in the Sn--Sb system increases, but unexpectedly. It was also found that when Sb is contained in a relatively high region of 5 to 15% by weight and Ag is contained in the range of 2 to 15% by weight, excellent ductility at 170 ° C is exhibited due to the synergistic effect. Further, since cold working can be satisfactorily performed in this range, the intended composite material can be obtained, and the present invention has been completed. The present invention is as follows. (First invention) In a composite solder material containing powder in the solder material, the solder material is Sb 5 to 15% by weight, Ag 2 to 15
% By weight, the balance being substantially S except for unavoidable impurities.
A composite solder material comprising n. (Second invention) In a method for producing a composite solder material containing powder in a solder material, Sb 5 to 15% by weight, Ag 2 to 15
% By weight, the balance being substantially S except for unavoidable impurities.
A method of manufacturing a composite solder material, comprising cold working a solder material consisting of n. (Third invention) A composite solder material according to the first invention, wherein the powder content of the composite solder material is 0.001 to 1.0% by weight. (4th invention) In the 2nd invention, the powder content of the composite solder material is 0.001 to 1.0% by weight.

[0009]

The operation and more detailed constitution of the present invention will be described below. Explaining the reason why the composition of the solder material is limited as described above, regarding the solder containing Sn as a main component, S
b has the effect of improving the ductility at 170 ° C. in the synergistic effect with Ag. The Sb content needs to be 5 to 15% by weight, and within this range, an effect of improving ductility at 170 ° C is produced. The content is more preferably 6 to 11% by weight, and in this range, the improvement of ductility at 170 ° C. shows a more excellent effect.
And cold workability is favorable in these ranges. If the Sb content is less than 5% by weight, the effect of improving ductility at 170 ° C is insufficient. On the other hand, if the Sb content exceeds 15% by weight, the ductility improving effect is insufficient and cold working becomes impossible.

Ag has a synergistic effect with Sb at 170 ° C.
It is effective in improving ductility. The content of Ag needs to be 2 to 15% by weight, and within this range, an effect of improving ductility at 170 ° C. occurs. More preferably 6 to 12% by weight
In this range, the improvement of ductility at 170 ° C. shows a more excellent effect. Cold working is possible within these ranges. If the Ag content is less than 2% by weight, the effect of improving ductility at 170 ° C is insufficient. On the other hand, if the Ag content exceeds 15% by weight, the ductility improving effect is insufficient and cold working becomes impossible.

In the Sn—Sb type solder, the lower the Sb content, the lower the normal strength and the higher the ductility. Therefore, when the Sb content is as small as 3% by weight, 170 is more preferable.
Although it is expected that the ductility at C is also large, the reason why the higher Sb content of 5 to 15% by weight as in the present invention has an excellent effect of improving ductility at 170 ° C. is not clear.
It is considered to be due to the synergistic effect of n, Sb, and Ag.

Next, the manufacturing method of the present invention will be described.
The solder material of the present invention comprises Sn, Sb and Ag in a predetermined amount, melts them in an inert atmosphere, and casts them to prepare a rolling ingot or an extruding ingot. The rolling ingot is used as a solder tape by rolling, and then two solder tapes are inserted between two rolling rolls arranged vertically or horizontally, and two solder tapes are joined before joining the two solder tapes. A cold work material of the composite solder material tape according to the present invention is obtained by a method of supplying a predetermined powder in the meantime and filling the powder into the inside of the solder material by the biting force of a rolling roll. The extrusion ingot is provided with a cavity in the ingot,
A cold work material for a composite solder material tape or wire according to the present invention is obtained by a method of filling powder in the cavity and extruding. These cold-worked materials are rolled or drawn to produce cold-worked composite solder material tapes or wires having a thickness or outer diameter of 30 to 300 μm. Further, the cold-worked composite solder material tape may be pressed into a pellet form for use.

The following powders are used here. (1) It has a melting point of at least 50 ° C. higher than the solder material used. (2) Examples of materials Metal particles: Cu, Ni, Mo, W Oxides: Al ₂ O ₃ , TiO ₂ , Cr ₂ O ₃ , ZrO
₂ Others: Carbides, nitrides, borides and the like. From the viewpoint of wettability with solder, metal particles and oxides are preferably used. (3) Shape and dimensions Dimensions: 5 to 100 μm are preferably used. Shape: An irregular shape and a spherical shape can be used, but a spherical shape is preferable. (4) A powder having a powder content of 0.001 to 1.0% by weight in the composite solder material is preferably used. Further, 0.001 to 0.6% by weight is more preferably used.

[0014]

【Example】

(Example 1) A solder ingot having a diameter of 70 mm and a length of 100 mm was prepared by blending each metal element in the solder of the cold-worked composite solder wire so as to have the composition shown in Table 1, melting and casting in a nitrogen atmosphere. It was created. This solder ingot was provided with a cavity, and Ni powder was pressurized and filled in the cavity, the cavity was capped with the same solder material, heated to 150 ° C., and extruded into a wire having a diameter of 1 mm. Furthermore, wire drawing was carried out to finish the thin wire with a diameter of 0.3 mm. The cold workability in that case is shown in Table 2.
Shown in Next, the wire drawing material was subjected to a tensile test in a state of being heated at 170 ° C., and the elongation was measured. The results are shown in Table 2.
Shown in

(Examples 2 to 14, Examples 16 to 19 and Comparative Examples 1 to 6) Each metal element in the solder wire was blended so as to have the composition shown in Table 1 and melted and cast in a nitrogen atmosphere. , An ingot with a diameter of 70 mm and a length of 100 mm was prepared. This was heated to 150 ° C. and extruded into a wire having a diameter of 1 mm. Furthermore, wire drawing was carried out to finish the thin wire with a diameter of 0.3 mm. Table 2 shows the cold workability at that time. Next, the wire drawing material was subjected to a tensile test in a state of being heated at 170 ° C., and the elongation was measured. The results are shown in Table 2.

Example 15 Each metal element in the solder ribbon was blended so as to have the composition shown in Table 1, melted and cast in a nitrogen atmosphere to prepare an ingot having a diameter of 30 mm and a length of 100 mm. This is heated to 150 ℃, thickness 1mm × width 2
Extruded to 0 mm. Further, it was rolled into a tape having a thickness of 0.3 mm and a width of 20 mm. Table 2 shows the cold workability at that time. Next, this rolled material was subjected to a tensile test in a state where it was heated to 170 ° C., and the elongation was measured. The results are shown in Table 2.

[0017]

[Table 1]

[0018]

[Table 2]

Here, cold workability means, in the case of a wire,
The number of wire breakages per kg of weight when wire drawing from a diameter of 1 mm to 0.3 mm was measured and evaluated as follows. ◯: When the number of wire breaks is 2 or less Δ: When the number of wire breaks is 3 to 4 ×: When the number of wire breaks is 5 or more Not possible: When wire drawing is not possible In the case of tape, rolling from 1 mm to 0.3 mm in thickness The size of the maximum edge crack in the tape width direction was measured, and the ratio to the tape width was taken as the edge crack rate and evaluated as follows. ◯: When the cracking rate is 5% or less Δ: When the cracking rate is more than 5% and less than 25% ×: When the cracking rate is 25% or less No: When rolling is not possible

As is clear from Tables 1 and 2, Sb5-1
Each of Examples 1 to 19 of the present invention, which is obtained by cold working a solder material containing 5 wt% and Ag 2 to 15 wt% and the balance being substantially Sn except the inevitable impurities, is excellent in cold workability. At the same time, it can be seen that the elongation at 170 ° C. is also good at 25% or more. Further, Example 2 in which the Sb content was 6 to 11% by weight and the Ag content was 6 to 12% by weight
It can be seen that in Nos. 6, 10 to 12, and 15 to 19, the elongation at 170 ° C is 38% or more, which is more favorable.

The powder content in the composite solder material is set to 0.
It can be seen that Examples 1 to 18 with 001 to 0.6% by weight have even better cold workability than Example 19 with the same content of 1.0% by weight.

On the other hand, even if the composition is of Sn-Sb-Ag system, Comparative Examples 2 and 4 in which the contents of Sb and Ag are out of the range of the present invention cannot be cold worked, and Sb , Ag
Comparative Examples 1 and 3 which contain only one of the above even if the content is within the range of the present invention have good cold workability, but the elongation at 170 ° C. is 15% or less. ,
Furthermore, the comparative example 5 and Sn which made Sn-Sb-Ni system composition
1 in Comparative Example 6 in which the —Sb—Ag—Cu system composition was used.
It can be seen that the elongation at 70 ° C. is 21% or less and cold working is impossible.

Next, the experimental examples shown in FIGS. 1 and 2 will be described. FIG. 1 shows a composite solder material having a Sb content of 8.5% by weight, an Ag content of 0 to 25% by weight, and the balance being substantially Sn except the inevitable impurities, which is obtained by cold working at 170 ° C. It is a graph which measured the elongation rate in. Figure 2
Is a composite solder material obtained by cold working a solder material consisting of Ag content of 7.5% by weight, Sb content of 0 to 15% by weight, and the balance being substantially Sn except for unavoidable impurities. It is a graph which measured the elongation rate.

As is clear from FIG. 1, the Ag content is 2
It can be seen that the elongation rate is as good as 25% or more in the range of ˜15% by weight, and the elongation rate is even better in the range of Ag content of 6 to 12% by weight. FIG. 2
As is clear from the above, the elongation percentage is as good as 25% or more in the Sb content range of 5 to 15% by weight, and the S
It can be seen that the elongation is even better when the b content is in the range of 6 to 11% by weight.

[0025]

As described above, the composite solder material according to the present invention has excellent cold workability and 170 ° C.
The elongation percentage in the tensile test in the above state is remarkably excellent. Therefore, when the powder-containing composite solder material is cold-worked to a predetermined size and used as a connecting material, it is possible to maintain the levelness of the semiconductor chip at a good level, and to use the Sn-Sb solder member with the heat generation of the semiconductor chip. It has an excellent effect of suppressing the generation of cracks. Therefore, it is extremely suitable for use in connection between a semiconductor chip and a lead frame substrate, for example.

[Brief description of drawings]

FIG. 1 Sb content is 8.5% by weight, Ag content is 0 to 2
17% of a composite solder material obtained by cold working a solder material which is 5 wt% and the balance is substantially Sn except for unavoidable impurities.
It is a graph which measured the elongation at 0 ° C.

FIG. 2 Ag content of 7.5% by weight, Sb content of 0 to 1
17% of a composite solder material obtained by cold working a solder material which is 5 wt% and the balance is substantially Sn except for unavoidable impurities.
It is a graph which measured the elongation at 0 ° C.

Claims (4)

[Claims] 1. A composite solder material containing a powder in a solder material, wherein the solder material is 5 to 15% by weight of Sb and 2 to Ag.
A composite solder material comprising 15% by weight and the balance being substantially Sn except for unavoidable impurities. 2. A method for producing a composite solder material containing a powder in a solder material, comprising 5 to 15% by weight of Sb and 2 to Ag.
A method for manufacturing a composite solder material, comprising a cold-working solder material containing 15% by weight and the balance being substantially Sn except for unavoidable impurities. 3. The powder content of the composite solder material is 0.001.
The composite solder material according to claim 1, wherein the composite solder material is about 1.0% by weight. 4. The powder content of the composite solder material is 0.001.
The method for producing a composite solder material according to claim 2, wherein the content is from 1.0 to 1.0% by weight.