JP2017070958A - Au-Sb-Sn SOLDER ALLOY - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive, Pb-free solder alloy for a high temperature which has a solidus line temperature of approximately 300°C or lower and is excellent in wettability, workability, stress relaxation, joint reliability and the like.SOLUTION: The solder alloy has an Sb content of 41.0 mass% or more and 52.0 mass% or less, preferably more than 46.7 mass% and 51.0 mass% or less, an Sn content of 2.0 mass% or more and 11.0 mass% or less, preferably more than 5.8 mass% and 9.0 mass% or less, with the balance being Au and unavoidable impurities.SELECTED DRAWING: None

Description

  The present invention relates to a so-called Pb-free solder alloy containing no Pb, and particularly to a Pb-free Au—Sb—Sn solder alloy suitable for high temperature use.

  Soldering in the assembly process of various electronic components including die bonding of power transistor elements is performed at high temperature, and a solder alloy having a relatively high melting point of about 300 to 400 ° C. (Hereinafter also referred to as “high temperature solder alloy”). As such a high temperature solder alloy, a Pb solder alloy typified by a Pb-5 mass% Sn alloy has been mainly used.

  However, in recent years, there has been a strong movement to limit the use of Pb due to consideration of environmental pollution caused by waste. For example, Pb is a regulated substance in the RoHS directive enforced in the European Union. In response to these movements, in the field of assembling electronic components and the like, replacement with Pb-free (lead-free) solder alloys, that is, Pb-free solder alloys, has already been promoted. In the case of a solder alloy of [° C.], a Pb-free solder alloy containing Sn as a main component has been put into practical use.

  For example, in Patent Document 1, Sn is the main component, Ag is 1.0 to 4.0 mass%, Cu is 2.0 mass% or less, Ni is 1.0 mass% or less, and P is 0.2 mass%. Pb-free solder alloys containing up to 10% are described. Patent Document 2 describes a Pb-free solder alloy containing 0.5 to 3.5% by mass of Ag, 0.5 to 2.0% by mass of Cu, and the balance being Sn.

  On the other hand, Au—Sn solder alloys and Au—Ge solder alloys have been put to practical use as high-temperature Pb-free solder alloys. For example, regarding Au-based solder and brazing material, Patent Document 3 discloses a lid or case for a sealed package including a frame-shaped Au-based brazing material on a joint surface. This frame-shaped brazing material is formed by arranging ball-shaped brazing materials having a particle diameter of 10 to 300 μm, and includes Au—Sn brazing material, Au—Ge brazing material, Au—Si. Examples thereof include a brazing filler metal and an Au—Sb brazing filler metal. However, these Au-based solder alloys are very expensive because they contain Au as a main component, and are limited to applications such as optical device-related elements that require high reliability, and are used for general electronic components and the like. There was hardly anything.

  Therefore, research and development of Bi-based solder alloys, Zn-based solder alloys, and the like are underway in order to realize Pb-free even in relatively inexpensive high-temperature solder alloys used for general electronic components and the like. For example, for a Bi-based solder alloy, Patent Document 4 discloses an Ag—Bi-based brazing material containing 30 to 80 at% Bi and having a melting temperature of 350 to 500 ° C. A solder alloy production method is disclosed in which the liquidus temperature can be adjusted and the variation can be reduced by adding another binary eutectic alloy to the eutectic alloy contained therein and further adding additional elements. As for the Zn-based solder alloy, for example, Patent Document 6 discloses a high-temperature Zn-based solder alloy based on a Zn-Al alloy in which Al is added to lower the melting point of Zn, and Ge or Mg is added thereto. ing. Patent Document 6 also describes that the addition of Sn or In has an effect of further lowering the melting point.

  Specifically, in Patent Document 6, Al is 1 to 9% by mass, Ge is 0.05 to 1% by mass, the remainder is a first Zn alloy composed of Zn and inevitable impurities, and Al is 5 to 9% by mass. %, Mg is contained in an amount of 0.01 to 0.5% by mass, and the balance is a second Zn alloy composed of Zn and inevitable impurities, Al is 1 to 9% by mass, Ge is 0.05 to 1% by mass, and Mg is 0%. A third Zn alloy containing 0.01 to 0.5% by mass, the balance being Zn and inevitable impurities, Al 1 to 9% by mass, Ge 0.05 to 1% by mass, Sn and / or In 0.5%. A fourth Zn alloy containing 1 to 25% by mass, the balance being Zn and inevitable impurities, Al 1 to 9% by mass, Mg 0.01 to 0.5% by mass, Sn and / or In 0.1% A fifth Zn alloy containing ~ 25% by mass, the balance being Zn and inevitable impurities, and 1-9% by mass of Al, and 0.5% of Ge. A sixth Zn alloy containing 5 to 1% by mass, Mg of 0.01 to 0.5% by mass, Sn and / or In of 0.1 to 25% by mass, the balance being Zn and inevitable impurities is described. Yes.

Japanese Patent Laid-Open No. 11-077366 Japanese Patent Laid-Open No. 08-215880 International Publication No. 2008/140033 JP 2002-160089 A JP 2006-167790 A Japanese Patent No. 3850135

  The Au-based brazing material of the above-mentioned Patent Document 3 has no detailed description of the composition. If the Au-Sn brazing material or the Au-Ge brazing material is used, Au near the eutectic point that is generally used is used. Although it can be estimated that it is -20 mass% Sn or Au-12.5 mass% Ge, the Au-Sb brazing material is hardly used in the world at present, and the composition is unknown. If the composition range is not specified, the liquidus temperature and the solidus temperature are of course not determined, and it is not known at all what kind of characteristics the alloy has. Therefore, the Au—Sb brazing material is actually sealed. It is difficult to use for lids and cases for fastening packages.

  The Ag-Bi brazing material described in Patent Document 4 has a liquidus temperature as high as 400 to 700 ° C, and it is presumed that the working temperature during joining, preferably less than 500 ° C, is 400 to 700 ° C or higher. It is considered that the temperature exceeds the heat resistance temperature of general electronic parts and substrates in which thermosetting resins are frequently used. In addition, the method of Patent Document 5 described above produces a complex multi-component solder alloy of quaternary system or more only for the purpose of adjusting the temperature of the liquidus, and is effective for Bi fragile mechanical characteristics. Improvement has not been made.

  The Zn-based solder alloy disclosed in Patent Document 6 often has insufficient wettability within the composition range. That is, although the melting point of Zn—Al alloy is in a preferable range of about 300 to 400 ° C. (Zn—Al eutectic temperature: 381 ° C.), Zn, which is the main component, is highly reducible and thus is easily oxidized. As a result, the wettability is considered to be extremely poor.

  Moreover, since Al is more reducible than Zn, for example, even when added in an amount of 1% by mass or more, the wettability is greatly reduced. These oxidized Zn and Al cannot be reduced even if Ge or Sn is added, and the wettability cannot be improved. Furthermore, when Mg or the like is added to the Zn—Al-based alloy, an intermetallic compound is generated and becomes extremely hard, and there is a problem that good workability may not be obtained. For example, a Zn—Al-based alloy containing 5% by mass or more of Mg cannot be processed into a wire shape or a sheet shape that is difficult to process.

  Thus, low-cost high-temperature Pb-free solder alloys that can replace conventional high-temperature solder alloys represented by Pb-5 mass% Sn alloy, Au-Sn alloy, Au-Ge alloy, etc. are still in practical use. The actual situation is not done. The present invention has been made in view of such circumstances, has a solidus temperature of about 300 ° C. or less suitable for applications such as assembly of electronic components, and has wettability, workability, stress relaxation properties, and bonding reliability. An object of the present invention is to provide a high-temperature Pb-free solder alloy which is excellent in properties and the like and is much cheaper than Au—Sn solder and Au—Ge solder.

  In order to achieve the above object, the Au—Sb—Sn solder alloy provided by the present invention has an Sb content of 41.0 mass% to 52.0 mass% and an Sn content of 2.0 mass%. The content is 11.0% by mass or less, and the balance is Au and inevitable impurities.

  According to the present invention, since it has a solidus temperature of about 280 ° C., it can sufficiently withstand a reflow temperature of about 250 ° C., is excellent in wettability, workability, stress relaxation property, bonding reliability, etc. It is possible to provide a Pb-free solder alloy for high temperatures that is much cheaper than Sn solder and Au—Ge solder.

It is a reaction scheme of an Au—Sb—Sn alloy. It is typical sectional drawing of the joined body for the wettability evaluation which soldered the solder alloy on Cu substrate which has Ni layer. It is a longitudinal cross-sectional view of the container for sealing performance evaluation sealed with the solder alloy.

  The Pb-free solder alloy according to the present invention contains Sb and Sn as essential components in an amount of 41.0% by mass to 52.0% by mass and 2.0% by mass to 11.0% by mass, respectively, and the balance is manufactured. It consists of an element unavoidably included (also referred to as an inevitable impurity) and Au. Au, which is the main component of the Pb-free solder alloy according to the present invention, has a melting point of 1064 ° C., which is too high for the bonding temperature of electronic parts and the like. In order to reduce the melting point of the Pb-free solder alloy mainly composed of Au having a high melting point to about 280 ° C. so that it can be used as a high-temperature solder alloy, the Pb-free solder alloy according to the present invention contains Sb and Sn. It is essential to contain it.

  That is, by using an Au—Sb—Sn solder alloy, the solidus temperature becomes about 280 ° C., and can sufficiently withstand a reflow temperature of about 250 ° C. As a result, Au-Sb-Sn series suitable for soldering in the assembly process of various electronic devices such as die bonding and sealing of electronic parts such as Si semiconductor element assemblies, SiC semiconductor element assemblies, power transistor elements, etc. A solder alloy can be provided. This Au—Sb—Sn solder alloy is particularly excellent as a sealing material for sealing a crystal resonator.

  The second important purpose of incorporating Sb and Sn into Au is to provide a solder alloy containing a eutectic structure. That is, by containing Sb and Sn, it is possible to make the composition near the eutectic point and thereby the crystal becomes finer. For example, the solder alloy is formed into a wire shape, ribbon shape, preform shape, ball shape, etc. It becomes very easy to process the solder material, and cracks are difficult to progress, and the stress relaxation property and the joint reliability are remarkably improved.

  Further, Sb is less likely to be oxidized than Sn and Ge used in commercially available Au-based solders. Therefore, inclusion of Sb can greatly contribute to the wettability of the solder. In particular, the solder alloy of the present invention has an extremely low Sn content compared to Au-20% by mass Sn, and an increased Sb content that is difficult to oxidize. Is obtained.

  As a more important purpose of containing Sb and Sn, the Sb content is 41.0% by mass or more and 52.0% by mass or less, and the Sn content is 2.0% by mass or more and 11.0% by mass or less. By adding more Sb and Sn than the Au-based solder alloy, the cost of the solder alloy is greatly reduced. For example, if the composition is in the vicinity of the eutectic point of the Au—Sb—Sn alloy, the Au content can be reduced by about 30% by mass or more compared to Au-20% by mass Sn. Needless to say, greatly reducing the content of such expensive Au greatly increases the application range and market scale of Au solder. Hereinafter, the Pb-free Au—Sb—Sn solder alloy of the present invention will be described in more detail.

  Au is an essential element constituting the main component in the Pb-free Au—Sb—Sn solder alloy of the present invention. Au has a melting point of 1064 ° C., which is a considerably high melting point as a solder material for electronic components, but can be greatly lowered by alloying with Sb or Sn. That is, Au forms a eutectic alloy with Sb and Sn, and the eutectic point temperature is 280 ° C., which is the same as that of the Au—Sn alloy, and can be lowered to a melting point that is very suitable as a high-temperature solder. Thus, by lowering the melting point to a temperature suitable for bonding of electronic parts and the like by alloying of Au, Sb and Sn, soldering of high temperature devices such as Si semiconductor elements can be performed in an optimum temperature region, In particular, it becomes a solder alloy suitable for sealing a crystal resonator.

This will be described with reference to a reaction scheme (G. Petzow and Effenberg, “Ternary Alloys, A Comprehensive Compendium of Evaluated Constitutional Data and Phase Diagrams”, VCH) of the Au—Sb—Sn alloy shown in FIG. As shown in FIG. 1, the Pb-free solder alloy of the present invention is basically composed of two intermetallic compounds of AuSb ₂ and Au ₁ Sn ₁ by using Au, Sb and Sn as essential components. Thus, the Sb content is 57 at% at the eutectic point. Since it is composed of AuSb ₂ and Au ₁ Sn _{1, the} Au content is 35.75 at% and the Sn content is 7.25 at%. That is, in terms of mass%, the Au content is 47.5 mass%, the Sb content is 46.7 mass%, the Sn content is 5.8 mass%, and the eutectic point temperature is 280 ° C. is there. The melting point of 280 ° C. is exactly the same as the eutectic point temperature of Au-20 mass% Sn, and therefore the solder alloy of the present invention is quite satisfactory as an alternative to Au-20 mass% Sn. This preferred melting point is one of the important features of the present invention.

As described above, since the solder alloy of the present invention includes a eutectic alloy having a fine crystal structure, it is excellent in workability and hardly cracks even when a load such as thermal stress is applied. difficult. In addition, Au ₁ Sn ₁ constituting the solder alloy of the present invention is an intermetallic compound itself constituting Au-20 mass% Sn solder, and AuSb ₂ is another alloy constituting Au-20 mass% Sn solder. There are more slip planes and more flexibility than some close-packed hexagonal Au ₅ Sn. For this reason, the Au—Sb—Sn solder alloy of the present invention is more excellent in workability and stress relaxation than Au—Sn solder alloy and Au—Ge solder alloy.

  Sb has an excellent property that it is less likely to be oxidized than Sn and Ge. By containing a large amount of this Sb, the solder alloy of the present invention has excellent wettability. That is, by containing a large amount of Sb that is difficult to oxidize, the solder alloy itself is less likely to be oxidized at the time of soldering or the like, and the wettability is remarkably improved. The solder alloy of the present invention is less susceptible to oxidation than the Au-20 mass% Sn alloy due to the effect of Sb, and therefore, the wet spreadability equal to or higher than that can be obtained.

  Furthermore, the low cost is mentioned as a big characteristic of the solder alloy of this invention. That is, Au-20 mass% Sn, Au-12.5 mass% Ge, Au-3.1 mass% Si and the like currently used as Pb-free solder alloys for high temperature have an Au content of about 80 to 97 mass%. There is a very high cost. On the other hand, the solder alloy of the present invention has an Au content of about 50% by mass, and the Au content can be reduced by about 30% by mass or more compared to the above-described conventional Au-based solder alloy, so that the cost is very low. It is obvious. This very low cost feature is a major feature of the solder alloy of the present invention, and the cost of the Au-based solder alloy, which is generally very expensive, can be reduced to half or less in some cases.

  The content of Sb for achieving the excellent effects as described above is 41.0% by mass or more and 52.0% by mass or less, preferably more than 46.7% by mass and 51.0% by mass or less. The content is 2.0% by mass or more and 11.0% by mass or less, preferably more than 5.8% by mass and 9.0% by mass or less. If the content of Sb is less than 41.0% by mass, the content is too small and too far from the composition of the eutectic point, the liquidus temperature becomes too high and bonding becomes difficult, and there are various kinds of Au and Sn. Intermetallic compounds are produced and become hard and brittle. On the contrary, if the Sb content exceeds 52.0% by mass, the difference between the liquidus temperature and the solidus temperature becomes too large, resulting in the phenomenon of melting and separation, and the proportion of Sb intermetallic compound is too high. As a result, the crystal becomes coarser, leading to a decrease in bonding reliability.

  In particular, if the Sb content exceeds 46.7% by mass and is 51.0% by mass or less, the reliability after bonding is further improved, which is preferable. That is, Sb reacts with Ni or Cu on the bonding surface during bonding, and the Sb content of the solder parent phase after bonding tends to be lower than the composition of the eutectic point, so that the solder composition is more Sb than the composition of the eutectic point. By containing, it becomes close to the composition of the eutectic point after bonding, and higher bonding reliability can be obtained.

  Further, if the Sn content is less than 2.0% by mass, the content is too small to be too far from the eutectic point, and various advantages of the eutectic point as a solder alloy cannot be obtained. On the other hand, if the Sn content exceeds 11.0% by mass, the content is too high and a low melting point phase is generated, or an intermetallic compound of Au and Sn is excessively generated and becomes hard and brittle.

  In particular, if the Sn content exceeds 5.8 mass% and is 9.0 mass% or less, the reliability after bonding is further improved, which is preferable. That is, the reason why the bonding reliability is improved by making the Sn content higher than the composition of the eutectic point is the same as in the case of Sb described above. However, since Sn reacts more easily with Ni or the like than Sb, it is more effective. Is likely to appear. In many cases, an Au layer is provided on the bonding surface. In such a case, since Au diffuses into the solder matrix, the amount of Au tends to increase. It is preferable to increase Sb.

[Example 1]
Hereinafter, the present invention will be described in more detail with reference to specific examples, but the present invention is not limited to these examples. First, Au, Sb, Sn, and Ge having a purity of 99.99% by mass or more were prepared as raw materials. Large flakes and bulk-shaped raw materials were cut and pulverized, etc. so as to be uniform with no variation in composition depending on the sampling location in the alloy after melting, and were reduced to a size of 3 mm or less. Next, a predetermined amount of these raw materials was weighed into a graphite crucible for a high-frequency melting furnace.

  The crucible containing the raw material was placed in a high-frequency melting furnace, and nitrogen was flowed at a flow rate of 0.7 L / min or more per 1 kg of the raw material in order to suppress oxidation. In this state, the melting furnace was turned on to heat and melt the raw material. When the metal began to melt, it was stirred well with a mixing rod and mixed uniformly so as not to cause local compositional variations. After confirming sufficient melting, the high frequency power supply was turned off, the crucible was quickly removed, and the molten metal in the crucible was poured into the solder mother alloy mold. The mold used was a plate-like alloy having a thickness of 5 mm, a width of 42 mm, and a length of 240 mm for rolling to produce a sheet or punched product.

  In this way, solder mother alloys of Samples 1 to 20 with various mixing ratios of the raw materials were produced. Each of the solder mother alloys of Samples 1 to 20 was subjected to composition analysis using an ICP emission spectroscopic analyzer (SHIMAZU S-8100). The obtained analysis results are shown in Table 1 below.

  Next, for each of the solder mother alloys of Samples 1 to 20, the first workability is obtained by processing into a sheet using a warm rolling mill as shown below and examining the occurrence rate of cracks and the like. It was evaluated. Then, this sheet-like sample is used to make a preform material (punched product) by punching into a 0.5 mm × 0.4 mm rectangle with a press machine, and the pass rate of the punched product is examined to perform the second processing. Evaluation of sex.

<Manufacture of sheet (processability evaluation 1)>
The prepared plate-shaped mother alloy sample having a thickness of 5 mm, a width of 42 mm, and a length of 240 mm was rolled with a warm rolling mill. The rolling conditions were the same for all samples. Specifically, the number of rolling was 5 times, the rolling speed was 15 to 30 cm / second, the roll temperature was 250 ° C., and rolling was performed to 30.0 ± 1.2 μm by 5 times rolling. In each sample after rolling, “O” indicates that no cracks or burrs are generated per 10 m of the sheet, “Δ” indicates that 1 to 3 or more cracks or burrs are generated, and 4 or more cracks or burrs are generated. In this case, “x” was designated as the first workability evaluation.

<Punching (workability evaluation 2)>
Each sample processed into a sheet was punched with a press to produce a punched product, and the second workability was evaluated. Specifically, a rectangular punched product having a length of 0.5 mm and a width of 0.4 mm was manufactured by punching 1000 samples. At that time, if there are cracks, burrs, burrs, etc. in the punched product, it will be considered as a defective product, and if there is no such product and it will be punched into a clean square, it will be considered as a non-defective product. Was used to calculate the pass rate (%). The results of the above processability evaluations 1 and 2 are shown in Table 2 below.

  As can be seen from Table 2, each of the solder alloys of Samples 1 to 10 that satisfy the requirements of the present invention exhibits good characteristics in each evaluation item. That is, in the evaluation of the workability to the sheet, defects such as cracks did not occur, and the pass rate of the punched product was 99% or more, indicating a very high pass rate. On the other hand, each solder alloy of Samples 11 to 20, which is a comparative example of the present invention, resulted in an undesirable result in at least any of the characteristics. That is, in the evaluation of sheet workability, there were many samples in which cracks and the like occurred, and the acceptance rate of the punched product, which is evaluation of workability, was 88% at the highest.

[Example 2]
In the same manner as in Example 1, solder mother alloys of Samples 21 to 40 having different raw material mixing ratios were prepared. However, unlike Example 1, balls were used for the mold into which the molten metal in the crucible melted in the high-frequency melting furnace was poured. A cylinder with a diameter of 27 mm was used for submerged atomization for manufacturing. In the same manner as in Example 1, each solder mother alloy was subjected to composition analysis using an ICP emission spectroscopic analyzer (SHIMAZU S-8100). The analysis results are shown in Table 3 below.

  Next, each of the solder mother alloys of Samples 21 to 40 is processed into a ball shape using a submerged atomizer, and the void ratio of the joined body obtained by joining the obtained solder balls to the substrate is measured. Then, the bondability was evaluated, and the reliability was evaluated by conducting a heat cycle test of the bonded body. Moreover, the sealing state was evaluated by confirming the leakage state of the sealing body obtained by sealing with solder balls. Hereinafter, the manufacturing method and various evaluations of such ball-shaped solder will be specifically described.

<Method of manufacturing ball solder>
Each of the prepared solder mother alloys (columns of 27 mm in diameter) of samples 21 to 40 is put into a nozzle of a submerged atomizer, and this nozzle is heated to 300 ° C. above the quartz tube containing the liquid (high frequency melting coil) Set inside). As the liquid, oil having a great effect of suppressing the oxidation of solder was used. And after heating the mother alloy in a nozzle to 530 degreeC with a high frequency and hold | maintaining for 5 minutes, pressure was applied to the nozzle with the inert gas and it atomized and the ball-shaped solder alloy was produced. Note that the inner diameter of the nozzle tip was adjusted in advance so that the set value of the ball diameter was 0.30 mm. The obtained solder balls of each sample were washed with ethanol three times, and then dried in a vacuum at 45 ° C. for 2 hours using a vacuum dryer.

<Evaluation of bondability (measurement of void fraction)>
In order to evaluate the bondability, a bonded body was prepared using each of the samples 21 to 40, and the void ratio was measured. Specifically, a wettability tester (apparatus name: atmosphere control type wettability tester) is started, a double cover is applied to the heater part to be heated, and nitrogen gas is supplied from four locations around the heater part at 12 L / min. The flow rate was. Thereafter, the heater was set to a temperature higher than the melting point by 50 ° C. and heated.

  After the heater temperature has stabilized at the set value, a Cu substrate (plate thickness: 0.3 mm) plated with Ni (film thickness: 3.0 μm) is set in the heater part and heated for 25 seconds, and then each ball-shaped The solder alloy sample was placed on a Cu substrate and heated for 25 seconds. After the heating was completed, the soldered Cu substrate was picked up from the heater portion, and once installed and cooled in a place where the nitrogen atmosphere next to it was maintained, after sufficiently cooling, it was taken out into the atmosphere.

  In this manner, a joined body in which the solder alloy 3 of each sample was soldered onto the Cu substrate 1 having the Ni layer (plating) 2 as shown in FIG. And the void ratio was measured with respect to the obtained joined_body | zygote using the X-ray transmissive apparatus (The Toshiba Corporation make, TOSMICRON-6125). Specifically, X-rays were transmitted from the upper part of the joined body in a direction perpendicular to the joint surface between the solder alloy and the Cu substrate, and the void ratio was calculated using the following calculation formula 1.

[Calculation Formula 1]
Void ratio (%) = void area / (void area + joint area between solder alloy and Cu substrate) × 100

<Heat cycle test (reliability evaluation)>
In order to evaluate the reliability of solder bonding, a heat cycle test was performed on each solder ball of Samples 21-40. Note that this test was performed using two joined samples prepared in the same manner as the evaluation of the bonding property. First, for each of the two bonded samples, cooling at −40 ° C. and heating at 250 ° C. were taken as one cycle, and this was repeated for 300 cycles and 500 cycles, respectively. Then, these bonded bodies were embedded in resin, cross-section polishing was performed, and bonded surfaces were observed with SEM (S-4800, manufactured by Hitachi, Ltd.). The case where the joint surface was peeled or cracked in the solder was indicated as “×”, and the case where there was no such defect and the same joint surface as in the initial state was maintained as “◯”.

<Evaluation of sealing performance (confirmation of leak condition)>
In order to confirm the sealing performance by the solder alloy, as shown in FIG. 3, the container 4 having an opening in the upper portion was sealed using each solder alloy 3 of the samples 21 to 40. Specifically, it was sealed using a simple die bonder (made by West Bond, MODEL: 7327C), held at a temperature 50 ° C. higher than the melting point in a nitrogen flow (8 L / min) for 30 seconds, and then a nitrogen-flowed side. The box was sufficiently cooled to room temperature, and then the sealing body was taken out into the atmosphere. Each sealing body sealed in this way was immersed in water for 2 hours, and then the sealing body was taken out from the water and disassembled to confirm a leak state. When water was contained in the disassembled sealed body, it was judged that there was a leak and evaluated as “×”, and when there was no such leak, it was evaluated as “◯”. Table 4 below shows the evaluation results of the bondability, reliability, and sealability.

  As can be seen from Table 4 above, each of the solder alloys of Samples 21 to 30 satisfying the requirements of the present invention exhibits good characteristics in each evaluation item. In other words, it was confirmed that almost no voids were generated with respect to the void ratio, which is an evaluation of bondability. Furthermore, in the heat cycle test, which is an evaluation of reliability, no defect occurred up to 500 cycles for all samples. There was no leak in the evaluation of sealing performance, and good sealing performance was confirmed. It can be said that the reason why such a good result was obtained was that the solder alloy of the present invention was in an appropriate composition range and the solder alloy was produced under appropriate conditions.

  On the other hand, each of the solder alloys of Samples 31 to 40, which is a comparative example of the present invention, resulted in an undesirable result in at least any of the characteristics. That is, the void ratio, which is an evaluation of bondability, was about 0.7 to 11%, and voids were generated at a considerable rate. In the heat cycle test, which is an evaluation of reliability, defects occurred in all the samples except for the samples 39, 40 up to 300 cycles, and in the sealability evaluation, leaks were observed in all the samples except the samples 39, 40. Occurred.

  In both Examples 1 and 2, the solder alloys of Samples 1 to 10 and Samples 21 to 30 that satisfy the requirements of the present invention have a maximum Au content of about 53% by mass, and are currently in practical use. It can be seen that the Au content is significantly lower than the 80 mass% Au-20 mass% Sn alloy, 88 mass% Au-12 mass% Ge alloy, etc., which are low in cost.

1 Cu substrate 2 Ni layer 3 Solder alloy 4 Container

Claims (4)

  The Sb content is 41.0% by mass or more and 52.0% by mass or less, the Sn content is 2.0% by mass or more and 11.0% by mass or less, and the balance is Au and inevitable impurities. Au-Sb-Sn based solder alloy.   The content of Sb is at least 46.7% by mass and 51.0% by mass or less, or the content of Sn is more than 5.8% by mass and 9.0% by mass or less. The Au—Sb—Sn based solder alloy according to claim 1.   An Si-semiconductor element assembly that is bonded using the Au—Sb—Sn solder alloy according to claim 1. A crystal resonator sealing element, wherein the element is sealed using the Au—Sb—Sn solder alloy according to claim 1.

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