GB2155036A

GB2155036A - Semiconductor device

Info

Publication number: GB2155036A
Application number: GB08504656A
Authority: GB
Inventors: Susumu Okikaway; Hiroshi Mikino; Hiromichi Suzuki; Wahei Kitamura; Daiji Sakamoto
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1984-02-24
Filing date: 1985-02-22
Publication date: 1985-09-18
Also published as: GB2155036B; GB8803056D0; FR2561446A1; GB2200135B; GB8803057D0; HK94990A; FR2561446B1; HK95190A; MY101028A; GB2199846B; GB2200135A; GB2199846A; GB8504656D0; IT1183375B; SG82790G; IT8519571A0; DE3506264A1; HK95090A

Abstract

A semiconductor device (1) in which a pellet (3) and external leads are connected by wires (6) made of aluminium containing a predetermined amount of impurity, the impurity being at least one of 0.05-3.0 weight % of iron and 0.05-3.0 weight % of palladium. Alternatively the impurities are at least one of 0.05-3.0 weight % of nickel, 0.05-3.0 weight % of iron and 0.05-3.0 weight % of palladium and at least one of 0.5-3.0 weight % of magnesium, 0.5-3.0 weight % of manganese and 0.5-3.0 weight % of silicon. By these choices, the corrosion resistance of the wire can be increased, the breaking strength of the wire can be enhanced, and the hardness of a ball portion formed at an end of the wire may be set at a predetermined value, preferably 35-45 Hv. <IMAGE>

Description

SPECIFICATION Semiconductor device The present invention relates to a semiconductor device, and more particularly to a semiconductor device having wires of aluminium or an aluminium alloy.

Japanese Laid-open Patent Application No. 51-140567 discloses a semiconductor device wherein a ball is formed at the distal end of an aluminium wire by means of an electric torch or the like so as to permit ball bonding.

Although aluminium wire is low in cost, it is inferior in corrosion resistance. Especially when used in a so-called resin-molded package, the wire corrodes, reducing reliability. Another problem is that aluminium wire is lower in mechanical strength, as compared with gold wire.

In the case of the ball bonding of aluminium wire, the present inventors have found the problem that peeling of the bonding wire occurs particularly on the bonding pad side of a pellet, so the bonding performance is poor.

The present inventors have discovered that the hardness of the ball when forming the ball portion in the aluminium wire exerts great influence on the bonding performance. More specifically, when the ball is too soft, ultrasonic energy does not act sufficiently on the bonding portion when the aluminium film of the bonding pad and the ball portion of the aluminium wire are subjected to ultrasonic bonding. For this reason, the plane of aluminium having an active surface energy state is not exposed, so that the peeling of the bonding wire occurs. On the other hand, when the aluminium ball is too hard, the force applied at the bonding step exercises large forces on the silicon layer, the silicon dioxide layer, etc. which underlie the aluminium pad, so that these layers undergo bonding damage such as cracks.

Upon making studies on the basis of the aforementioned realisations, the inventors have discovered suitable compositions for an aluminium wire which can allow good ball bonding while effectively preventing the corrosion of the aluminium wire.

The inventors have also found that, in ball-bonding of aluminium wire, deterioration in the strength of the wire can take place due to a high temperature which arises at, for example the heating of a low-melting glass to seal the package, so again the reliability of the semiconductor device may be jeopardized.

Further, it has been found by the inventors that, when the wire has an unsuitable strength, its bonding becomes difficult leading to a poor loop shape or to a too high or too low loop, which may for example cause the breakage or movement of the wire, or a short-circuit.

To counter this last problem, the inventors have created a technique which can maintain the strength of the aluminium wire while preventing the corrosion thereof. The invention can also provide various other improvements in the wires and their bonding, as discussed below.

According to the present invention in one aspect an aluminium wire used in a semiconductor device contains at least one of 0.05-3.0 weight % of iron and 0.05-3.0 weight % of palladium.

According to another aspect of the invention, an aluminium wire used in a semiconductor device contains firstly at least one of 0.05-3.0 weight % of nickel, 0.05-3.0 weight % of iron and 0.05-3.0 weight % of palladium, and secondly at least one of 0.5-3.0 weight % of magnesium, 0.5-3.0 weight % of manganese and 0.5-3.0 weight % of silicon.

According to the invention in another aspect, an aluminium wire used in a semiconductor device contains nickel, and the Vickers hardness of a bonding ball portion thereof is in the range 35-45.

Further, the breaking strengths of an aluminium wire before and after the sealing of a package are preferably respectively set at appropriate values.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a sectional view of a semiconductor device which is an embodiment of the present invention; Figure 2 is an enlarged partial sectional view of a wire bonding portion in the semiconductor device of Fig. 1; Figures 3 and 4 are explanatory views showing the formation of a ball in an aluminium wire and the ultrasonic bonding thereof, respectively; Figure 5 is a diagram showing the relationship between the compositions of wires and the breaking loads thereof; Figure 6 is a sectional view of another semiconductor device which is an embodiment of the present invention; Figure 7 is a diagram showing the relationship between the compositions of wires and the hardness of the ball portions of the wires; and Figure 8 is a graph showing the bonding damage and peeling occurrence percentages plotted against the Vickers hardness of the ball portions of wires.

In the semiconductor device shown in Fig. 1, a pellet 3 of, for example, silicon is mounted on a tab 2 by a joint layer 4 which is made of, for example a gold-silicon eutectic or a binder such as silver paste. The bonding pad of the pellet 3 is an aluminium pad 5 as shown in Fig. 2.

The bonding wire 6 shown is an aluminium-based wire made of aluminium or an aluminium alloy. The bonding wire 6 electrically connects the aluminium pad 5 of the pellet 3 with an aluminium layer 14 which is formed on the inner lead portion 7 of lead 1.

After wire bonding has been completed, the pellet 3, the bonding wire 6, etc. are encapsulated by a molded plastics resin 8.

To bond the bonding wire 6 by a ball-bonding process, as illustrated in Fig. 3, a ball portion 6a is formed at the distal end of the wire 6 by electric discharge between this end of the wire 6, which is held by a wire bonder (not shown), and the electrode 9 of the wire bonder. By appropriate choice of the material of the wire as described later, the ball portion 6a can have a hardness suitable for the bonding.

Immediately after the ball portion 6a has been formed, it may be quenched by blowing an inert gas, for example argon, at a low temperature against it, to obtain a desired ball hardness.

Whatever composition the wire may have, quenching is helpful for attaining a predetermined hardness.

Using an ultrasonic bonding tool 10, e.g. as shown in Fig. 4, the ball portion 6a is pressed against the aluminium pad 5 on the pellet 3 and is firmly bonded by ultrasonic oscillations. An Al2O3 film at the surface of the ball portion 6a is broken in this bonding step, and a good wire connection is obtained. The ball portion 6a is deformed to form the bonding portion 6b, which covers the aluminium pad 5 which is exposed at an opening of a final passivation film 13.

The wire 6 of the present embodiment is made of an aluminium alloy in which, in order to enhance moisture resistance, the principal ingredient, which is aluminium, has at least one additional element, in the form of 0.05-3.0 weight % of iron (Fe) and 0.05-3.0 weight % of palladium (Pd).

The reason why the moisture resistance of the wire can be enhanced by the presence of at least one of iron and palladium in the amounts specified is as follows.

In a high temperature and high humidity test such as MIL883B, which is a typical test method for corrosion resistance, the hydrogen of the water present becomes atomic hydrogen H.

Since atomic hydrogen H is small, it permeates the grain boundary of aluminium easily. When the hydrogen atoms H react together into gaseous hydrogen H2, their volume expands causing spreading of the grain boundary. Corrosion proceeds from the spread grain boundary. On the other hand, in aluminium wire which contains iron or palladium, the bonding of the atomic hydrogen H is promoted by the catalytic action of the iron or palladium in the crystal grain of aluminium. As a result, the atomic hydrogen H becomes gaseous hydrogen H2 at the surface of the aluminium without permeating the grain boundary thereof. Accordingly, the wire has resistance to corrosion. In other words, it is considered that the occlusion of H2 into the aluminium alloy wire is suppressed by the action of the iron or palladium, so grain boundary corrosion is prevented.

The inventors have conducted experiments on the relationship between the composition of the wire and the properties thereof, and the results are listed in Table 1.

In Table 1, the leftmost column indicates the compositions of the wires. For example, A1-0.05 Fe denotes an aluminium wire which contains 0.05 weight % of Fe. The other columns indicate, for the respective test periods of time, the cumulative numbers of samples which corroded when 10 samples of each wire were let stand at 1 21 C under a steam pressure of 2 atmospheres. The aluminium used was one having a purity of 99.999 weight %.

TABLE 1

Period of time # [ hr ] 20 40 60 80 100 200 400 600 Catposition Al 2 10 - - - - - Al - 0.05 Fe 2 5 10 - - - - Al - 0.1 Fe 0 0 0 0 0 2 3 4 Al - 0.5 Fe 0 0 0 0 0 0 0 0 Al - 1.0 Fe 0 0 0 0 0 0 0 0 Al - 2.0 Fe 0 0 0 0 0 0 0 0 Al - 3.0 Fe 0 0 0 0 0 0 0 0 Al - 0.05 Pd 0 0 0 0 0 1 3 4 Al - 0.1 Pd 0 0 0 0 0 0 0 0 Al - 0.5 Pd 0 0 0 0 0 0 0 0 Al - 1.0 Pd 0 0 0 0 0 0 0 iO 0 Al - 2.0 Pd 0 0 0 0 0 0 0 0 Al - 3.0 Pd 0 0 0 0 0 0 0 0 It is understood from Table 1 that the corrosion resistance of the aluminium wire is improved by adding iron or palladium. With a content of iron of up to 0.05 weight %, a great improvement is not obtained.This is because the catalytic action is insufficient due to the small amount of the iron present. Palladium is more effective to achieve improvement than iron. The aluminium wire containing at least 0.5 weight % of iron or at least 0.1 weight % of palladium does not corrode even when 600 hours have elapsed.

The mechanical strength of the aluminium wire can be increased simultaneously with the corrosion resistance thereof.

To this purpose, the wire 6 is formed of an aluminium alloy wire which contains firstly at least one of 0.05-3.0 weight % of nickel, 0.05-3.0 weight % of iron and 0.05-3.0 weight % of palladium, and secondly at least one of 0.5-3.0 weight % of magnesium, 0.5-3.0 weight % of manganese and 0.5-3.0 weight % of silicon.

Nickel increases the moisture resistance of the aluminium wire for the same reason as that or iron or palladium. The grain boundary corrosion of the aluminium wire can be prevented by adding the nickel at the predetermined proportion.

Table 2 shows that, when aluminium wire contains nickel, the corrosion resistance thereof is improved. The test method and the expression of results for this table are the same as for Table 1. The purity of the aluminium was of 99.999 %.

It is understood from Table 2 that the aluminium wire has its corrosion resistance improved by inclusion of nickel.

TABLE 2

Period of Time [ iirj 10 10 20 30 40 50 100 200 300 500 Composition ~ ~ Al 0 2 6 10 - - - - 8 10 Al - 0.01 Ni 0 0 5 8 10 - - - - Al - 0.02 Ni ~ ~ 0 0 0 0 2 5 10 ~~ Al - 0.03 Ni 0 0 0 0 0 5 10 - Al - 0.04 Ni 0 0 0 0 0 0 5 10 Al - 0.05 Ni 0 0 0 0 0 0 ~ 0 2 5 Al - 0.075 no 0 0 0 0 0 0 0 0 0 Al - 0.10 Ni 0 0 0 0 0 0 0 0 0 Al - 1.0 Ni 0 0 0 0 0 0 0 0 0 Al - 2.0 Ni 0 0 0 0 0 0 0 0 0 Al - 3.0 Ni 0 0 0 0 0 0 0 ~ 0 0 Al - 4.0 Ni 0 O 0 0 0 0 0 0 0 0 Al - 0.05 to 2.0 M 0 2 2 5 10 - - - Al - 1.5 Mo - 0.1 Ni 0 0 0 0 0 0 0 0 0 Al - 1.0 Mn - 0.1 Ni 0 0 0 0 0 0 0 0 0 Al - l.0 MR - 0.1 Fe 1 0 0 0 0 0 0 5 10 Al - 1.5 N - 0.25 Cr 1 0 10 - - - - - - The elements used other than nickel, for example, magnesium and chromium are not effective for the improvement of the corrosion resistance. With a nickel content of 0.02 weight %, a great improvement is not obtained. This is because the catalytic action is insufficient due to the small amount of the nickel present. The aluminium wire containing at least 0.075 weight % of nickel does not corrode even when 500 hours have elapsed.

As is apparent from Tables 1 and 2, nickel is more effective for the improvement of the corrosion resistance than iron or palladium. As Table 2 shows, a wire which contains nickel and one of magnesium and manganese also has excellent corrosion resistance. With magnesium only, the corrosion resistance is not improved. The wires containing nickel are excellent.

An aluminium wire containing any of nickel, iron and palladium has its mechanical strength increased by adding thereto any of magnesium, manganese and silicon at a predetermined proportion. The increase of the mechanical strength prevents defects such as disconnection and short-circuit attributed to the breaking of the wire, the movement of wire on injection of the resin, etc.

Fig. 5 indicates the strengths of various aluminium wires containing the aforementioned impurities.

In Fig. 5, the horizontal axis indicates the wire compounds i.e. the compositions of the wires.

For example, "0.5 Pd" signifies a wire which is made of Al containing 0.5 weight % of Pd.

The vertical axis represents tensile forces or loads Cgl at which the wires pulled by a fixed force broke. The diameter of all the wires was 30 jtm. The graph at the lower part of Fig. 5 shows the initial strengths of the wires. The initial strength signifies the strength of the wire which was as drawn from an aluminium ingot and which had experienced no annealing. The graph at the upper part of Fig. 5 indicates the strengths of the wires after annealing. Here, the "annealing" signifies that the wire 6 is subjected to a high temperature of 400-500 C for 2-10 minutes by way of example. The strength of the wire 6 is reduced by the annealing.

The inventors have discovered that the initial strength of the wire needs to be at least about 20 grams (9) for a wire having a diameter of 30 microns.

The strength not lower than 20 g is required when the aluminium ingot is drawn to form the aluminium wire, when the wire bonding is executed using the bonding tool 10 in Fig. 4, and so on. A wire whose strength is lower than 20 g is liable to break.

The inventors' discovery is that the reliability of a semiconductor device is affected by the aforementioned fact that the strength of the wire is degraded by the annealing.

Annealing at 400-500*C for 2-10 minutes as mentioned is unavoidable for semiconductor devices sealed with ceramic packages, including a semiconductor device as shown in Fig. 6.

That is, whatever sealant 16 may be used, the temperature and the period of time used to effect the sealing have the above values or values close thereto.

For example, in a case where a glass softening at low temperature is employed as the sealant 16, the sealing conditions are 400-500 C and 2-10 minutes; in a case where glass frit sealing is adopted, the sealing conditions are 400-500 C and 2-10 minutes similarly; and in a case where golt-tin (Au-Sn) is used so as to seal the semiconductor device with a metal cap, the sealing conditions are 200-300 C and 2-10 minutes.

Thus, the aluminium wire is inevitably annealed. It may be that the above temperature is the recrystallization point of the aluminium,wire which depends also upon the material of the wire, or a temperature close thereto.

According to the inventors' studies, the strength of the wire before annealing depends upon the workability and material thereof. The strength of the wire after the annealing depends only upon the material thereof. It does not depend upon the hysteresis of the wire because the wire has been annealed at the temperature close to the recrystallization point. In addition, the strength of the wire after annealing, i.e. after the sealing, needs to be at least 6 g for the diameter of 30 ,um. A wire whose strength is below 6 g is liable to break.

In Fig. 6, numeral 14 designates a ceramic base, and numeral 15 a cap.

In the semiconductor device having a ceramic package, the wire is selected taking into consideration the wire strengths before and after the annealing. In a resin-molded semiconductor device, the temperature of the sealing is comparatively low, e.g. about 170-180 C and hence, the wire strength is not so greatly reduced after the sealing. Accordingly, the wire strength after the annealing does not often pose a problem. However, particularly when the reliability is to be high, the strengths of the wire before and after the annealing should be considered.

When any of magnesium, manganese and silicon is further added to the aluminium wire containing any of nickel, iron and palladium, a wire of high corrosion resistance and of improved strength as indicated in Fig. 5 is produced.

As apparent from Fig. 5, especially a wire containing palladium or magnesium has a high breaking strength. Also, the breaking strength is high when any of silicon, manganese and magnesium is present in addition to palladium or magnesium. Particularly excellent are a wire containing iron and magnesium, a wire containing nickel and magnesium, a wire containing palladium and magnesium.

Of the aluminium wire containing 1.5 weight % of magnesium and 0.1 weight % of nickel (A1-1.5 Mg-0.1 Ni) and the aluminium wire containing 1.0 weight % of manganese and 0.1 weight % of nickel (A1-1.0 Mn-0.1 Ni) listed in Table 2, the former has higher breaking strength than the latter, though both have similarly excellent corrosion resistances.

Thus, the aluminium wire containing magnesium and nickel are excellent in both the corrosion resistance and the strength.

As a result of the inventors' studies, it is recommended for setting the strength in a proper range that magnesium, manganese and silicon are present in aluminium within the range of 0.5 weight % to 3.0 weight %.

In the case of a wire which is made of a recrystallized material composition, i.e. a wire which has been annealed at a temperature in a range from at least the recrystallization point of the wire to the recrystallization point plus 1 50 C or so, a loop can be formed in a very favourable manner and defects such as short circuit between a tab and wires can be prevented from occurring. The breaking strength is also enhanced.

When the wire 6 is an aluminium wire which contains nickel and any of magnesium, manganese and silicon, the Vickers hardness of the ball 6a has a value indicated in Fig. 7.

In Fig. 7 the vertical axis represents the Vickers hardness, and the horizontal axis the wire compounds or the composition of each material. The Vickers hardness of each material is indicated in a manner such that for example the value for Al is 18. Further, "0.5 Ni" indicates the wire made of Al containing 0.5 weight % of Ni.

The inventors conducted experiments on the relationships to the hardness of the aluminium ball portion 6a, of the occurrence percentage (%) of peeling between the bonding wire 6 and the aluminium pad 5 and the bonding damage occurrence percentage (%) by which cracks appear in a silicon dioxide layer 12 under the aluminium pad 5. The results shown in Fig. 8 were obtained.

A A permissible value for the occurrence percentage of the bonding defects is about 10%. In view of this, it is seen from Fig. 8 that the peeling occurrence percentage indicated by marks x) is high when the Vickers hardness is below about 30. In addition, the occurrence percentage of the bonding damages (indicated by marks o) is high when the Vickers hardne#ss is above about 50. As the optimum range, the range of Vickers hardness 35-45 is selected.

Thus, each wire 6 in the semiconductor device is selected so that the Vickers hardness (Hv) of the ball at the ball bonding may fall within the range of 35-45 as indicated in Fig. 7.

The material compositions of the wires 6 falling within the optimum hardness range include various possibilities. As the examples of the compositions of aluminium alloy wires capable of the most favourable ball bonding, there are mentioned a compound containing 1.0 weight % of nickel and 0.5 weight % of manganese, a compound containing 1.0 weight % of nickel and 1.0 weight % of manganese, a compound containing 0.5 weight % of nickel and 1.0 weight % of manganese, a compound containing 0.1 weight % of nickel and 1.5 weight % of magnesium, a compound containing 1.7 weight % of magnesium, 0.3-0.5 weight % of nickel and 0.3 % of iron, a compound containing 2 weight % of nickel and 1.0-2.0 weight % of silicon, and so forth.

These experimental results show that Ni principally contributes to the improvement of the corrosion resistance, while Mg, Mn or Si principally contribute to the adjustment of the hardness. It is also revealed that Ni does not spoil the effects of the hardness adjustments due to Mg etc., while contrariwise Mg etc. do not impede the increase of the corrosion resistance due to Ni. It is also apparent that Ni and Mg, or Mn and Si coexist stably in Al without spoiling the mechanical and electrical characteristics of the wire.

To summarize, the invention makes it possible for a wire whose principal ingredient is aluminium to be applied to a resin-molded semiconductor device, with high reliability being attained. This makes it possible to utilize the low cost of an aluminium-based wire effectively.

The ball bonding technique of an aluminium wire can be readily applied to a resin-molded semiconductor device.

The breaking strength of a wire after sealing in such a package is set at about 6 grams or above for a wire having a diameter of 30 microns, whereby breakage of the wire is prevented, and the reliability of the product can be enhanced.

The breaking strength of a wire before sealing in such a package is set at about 20 grams or above for the wire having a diameter of 30 microns, whereby strengths necessary for wire drawing etc. can be sufficiently secured, and disconnection can be prevented.

In a case where the material of a wire has been recrystallized, the formation of the wire into a loop can be normally executed and defects such as short-circuit can be prevented, and a sufficient breaking strength is also achieved.

By properly selecting the material of a wire, the breaking strength of the wire can be set at a predetermined value or above, and besides, the corrosion resistance and mechanical strength of the wire can be enhanced.

Since an aluminium wire contains nickel and the ball portion thereof has a Vickers hardness of 35-45, the corrosion resistance of the wire can be increased, and moreover, the bonding strength of the wire can be sufficient and the excess collapse of the ball portion as well as any damage to a bonding pad can be prevented, so that the reliability is enhanced.

Since the wire used contains aluminium as its principal ingredient, it can sharply reduce cost as compared with a gold wire.

The ball bonding of a wire whose principal ingredient is aluminium can, by the invention, be performed stably and easily, and the feature of low cost which is one of the merits of the aluminium-based wire can be exploited.

The working of a wire whose principal ingredient is aluminium can be facilitated by a proper ball hardness.

A wire which is excellent in bondability and which is also excellent in the corrosion resistance, the mechanical strength and the breaking strength can be provided by properly selecting the material of the wire.

While the invention has been illustrated above by various embodiments, the present invention is not restricted to such embodiments.

For example, the material composition of the wire is not restricted to those specifically mentioned before, but various other compositions can be employed.

The breaking strength of a wire changes depending upon the diameter thereof. In this regard, the present invention is not restricted only to a wire having a diameter of 30 microns, but it extends also to wires of different diameters by equalizing the breaking strength per unit area.

An aluminium wire according to the present invention is effective, not only when used for ball bonding, but also for ordinary ultrasonic bonding employing a wedge.

In the above, the invention has been chiefly illustrated applied to a semiconductor device employing a DILP type package, it is not restricted to this type of semiconductor device, and is extensively applicable to semiconductor devices employing various package types, for example, those of the surdip type, the laminated ceramic type and the chip carrier type.

Claims

1. A semiconductor device comprising a pellet, wires and external conductive portions which are connected with said pellet by said wires, wherein each wire is of aluminium containing at least one of 0.05-3.0 weight % of iron and 0.05-3.0 weight % of palladium.

2. A semiconductor device according to claim 1, wherein said semiconductor device is molded within a resin package.

3. A semiconductor device according to claim 1 or claim 2, wherein the aluminium of the wire contains iron in an amount of at least 0.5 weight %.

4. A semiconductor device according to claim 1 or claim 2, wherein the aluminium of the wire contains palladium in an amount of at least 0.1 weight %.

5. A semiconductor device wherein a pellet and external conductive portions are connected by wires, each wire comprising principally aluminium and containing firstly one of 0.05-3.0 weight % of nickel, 0.05-3.0 weight % of iron and 0.05-3.0 weight % of palladium, and secondly at least one of 0.5-3.0 weight % of magnesium, 0.5-3.0 weight % of manganese and 0.5-3.0 weight % of silicon.

6. A semiconductor device according to claim 5, wherein said semiconductor device is molded within a resin package.

7. A semiconductor device according to claim 5 or claim 6, wherein the aluminium of the wire contains iron in an amount of at least 0.5 weight %.

8. A semiconductor device according to claim 5, wherein the aluminium contains palladium in an amount of at least 0.1 weight %.

9. A semiconductor device according to claim 5 wherein the aluminium contains nickel in an amount of at least 0.075 weight %.

10. A semiconductor device comprising a pellet, wires and external conductive portions which are connected to said pellet by said wires, each said wire having a breaking strength equivalent to a breaking strength of at least about 6 grams for a diameter of 30 microns.

11. A semiconductor device according to claim 10, wherein said semiconductor device is sealed within a ceramic package.

12. A semiconductor device according to claim 10 or claim 11, wherein each said wire contains aluminium as its principal ingredient.

13. A semiconductor device according to claim 12, wherein the aluminium contains at least one of 0.05-3.0 weight % of iron and 0.05-3.0 weight % of palladium.

14. A semiconductor device according to claim 12, wherein the aluminium contains firstly at least one of 0.05-3.0 weight % of nickel, 0.05-3.0 weight % of iron and 0.05-3.0 weight % of palladium, and secondly at least one of 0.5-3.0 weight % of magnesium, 0.5-3.0 weight % of manganese and 0.5-3.0 weight % of silicon.

15. A semiconductor device according to claim 14, wherein the aluminium contains at least 0.5 weight % iron.

16. A semiconductor device according to claim 14, wherein the aluminium contains at least 0.1 weight % palladium.

17. A semiconductor device according to claim 14, wherein the aluminium contains at least 0.075 weight % nickel.

18. A semiconductor device according to any one of claims 14 to 17, wherein the aluminium contains magnesium.

19. A semiconductor device according to any one of claims 10 to 18, wherein said each wire has been heated to at least the recrystallization point thereof.

20. A semiconductor device comprising a pellet, wires and external conductive portions which are connected to said pellet by said wires, sealed within a package, each said wire having a a breaking strength before sealing within the package equivalent to a breaking strength of at least about 20 grams for a diameter of 30 microns.

21. A semiconductor device comprising a pellet, wires and external conductive portions which are connected with said pellet by said wires, each said wire being an aluminium wire containing nickel and having a bonding portion of a Vickers hardness of 35-45 formed at at least one end of the wire.

22. A semiconductor device according to claim 21 wherein the bonding portion is a bonding ball.

23. A semiconductor device according to claim 21 or claim 22, wherein said nickel is present in an amount of at least 0.075 weight %.

24. A semiconductor device according to claim 23, wherein each said wire contains at least one of 0.5-3.0 weight % of magnesium, 0.5-3.0 weight % of manganese and 0.5-3.0 weight % of silicon.

25. A semiconductor device according to claim 24, wherein each said wire contains 1.0 weight % of nickel and 0.5 weight % of manganese.

26. A semiconductor device according to claim 24, wherein each said wire contains 1.0 weight % of nickel and 1.0 weight % of manganese.

27. A semiconductor device according to claim 24, wherein each said wire contains 0.5 weight % of nickel and 1.0 weight % of manganese.

28. A semiconductor device according to claim 24, wherein each said wire contains 1.7 weight % of magnesium, 0.5 weight % of nickel and 0.5 weight % or iron.

29. A semiconductor device according to claim 24, wherein each said wire contains 2 weight % of nickel and 2 weight % of silicon.

30. A semiconductor device according to claim 24, wherein each said wire contains 2 weight % of nickel and 1 weight % of silicon.

31. A semiconductor device according to claim 24, wherein each said wire contains 0.1 weight % of nickel and 1.5 weight % of magnesium.