JP4780464B2 - Au-Ge alloy solder paste - Google Patents

Description

  The present invention relates to an Au-Ge alloy solder paste that has few voids at the soldering portion and joint interface during soldering and does not need to be cleaned after reflowing. Further, the Au-Ge alloy solder paste is an Au-plated substrate. The present invention relates to an Au—Ge alloy solder paste that is particularly effective for soldering.

Conventional technology

  In general, an Au—Ge alloy powder containing Ge: 1 to 50% by mass, the balance being composed of Au and inevitable impurities, and a particle size: 100 μm or less is used as a raw material powder for an Au—Ge alloy solder paste. It is known that there is known an Au—Ge alloy solder paste containing 80 to 95% by mass of this Au—Ge alloy powder and the balance being paraffin wax, liquid paraffin and tetralin. It is said that this Au—Ge alloy powder is preferably produced by the rotating electrode method rather than the gas atomization method (see Patent Document 1), and further contains 80 to 95% by mass of the Au—Ge alloy powder, with the balance being normal. An Au—Ge alloy solder paste made of a flux composed of rosin, an activator, a solvent and a thickener is also known. This Au-Ge alloy solder paste is used for bonding a semiconductor element such as a GaAs optical element, a GaAs high frequency element, a heat transfer element and a substrate, a SAW filter that requires fine and high airtightness, a package sealing for a crystal oscillator, etc. In particular, it is used for soldering a portion where high melting point bonding is possible.

In recent years, the package size has been rapidly reduced, and the size of the package to be sealed has been reduced to the dimensions of 1.6 mm in the vertical direction and 1.0 mm in the horizontal direction. The frame of the lid joint portion provided in the package having a package size of 1.6 mm in length and 1.0 mm in width has a narrow width of 100 to 250 μm, and the Au—Ge alloy solder paste is applied to the narrow frame. It is applied, and a lid is placed thereon and heated to seal the package. However, as the package size is further reduced, the width of the package frame becomes narrower. In order to seal packages such as SAW filters and crystal oscillators that require high airtightness by brazing to such a narrow frame, an alloy powder having a smaller particle diameter than before has been required. However, when an alloy powder having a small particle size is used, many voids are generated in the solder joint, and the airtightness is reduced due to the generation of voids, and the reliability with respect to soldering is reduced. In particular, the generation of large voids exceeding 25 μm is one of the biggest causes for reducing the hermetic performance of a small package.
Furthermore, in recent years, it is known to braze parts that are difficult to clean the brazed part by using non-corrosive non-halogen flux (for example, Deltalux 527N made by Senju Metal). In the case of brazing using this non-halogen flux, it has been widely used for brazing electronic parts that are particularly difficult to clean because the cleaning process of the brazed portion can be omitted.
Japanese Patent Laid-Open No. 3-155493

When brazing using the conventional Au—Ge alloy solder paste, large voids exceeding 25 μm are observed in the brazed portion, and the generation of such large voids provides reliable sealing of the small package as described above. I can't. Therefore, there has been a demand for a paste containing Au—Ge alloy powder that does not generate large voids exceeding 25 μm and has a smaller number of voids.
Furthermore, there has been a demand for an Au—Ge alloy solder paste that can eliminate the cleaning of the brazed portion.

The inventors of the present invention have studied to obtain an Au—Ge alloy paste in which the number of voids is smaller and large voids exceeding 25 μm are not generated, and further, the cleaning of the brazed portion can be omitted. as a result,
(A) Solder paste obtained by mixing Au: Ge alloy powder containing Ge: 10.5 to 15.5% by mass with the remainder consisting of Au and inevitable impurities in a commercially available non-halogen flux, When brazing using the solder paste, large voids exceeding 25 μm are not generated in the brazed portion, and the number of voids is further reduced as compared with the conventional Au—Ge alloy solder paste. (B) The patent document 1 describes that the Au—Ge alloy powder used for the solder paste is preferably a powder produced by the rotating electrode method rather than the gas atomized powder. However, Ge: 10.5 to 15.5% by mass near the eutectic point (Ge: 12.5% by mass) in the Au-Ge binary phase diagram. The Au—Ge alloy powder having the composition consisting of Au and inevitable impurities as the balance is mixed with a normal non-halogen flux to form an Au—Ge alloy solder paste than the powder produced by the rotating electrode method. The result of the study was that gas atomized powder is preferable.

This invention was made based on the results of such research,
(1) Ge: 10.5 to 15.5% by mass, the remainder contains 80 to 95% by mass of gas atomized Au—Ge alloy powder having a composition consisting of Au and inevitable impurities, and the remainder consists of non-halogen flux is an Au-Ge alloy solder paste.

Halogen-free flux contained in Au-Ge alloy solder paste of the present invention, reducing solid active agent comprising a saccharide having 4-6 water group, high viscosity solvent comprising a compound having an isobornyl group, and, alkanediol, alkylene glycols, Ru hydrocarbons, one or flux der mixed by blending the low viscous solvent of two or more selected from the group consisting of terpenes and ether.

(2) Ge: 10.5 to 15.5% by mass, with the remainder comprising 80 to 95% by mass of gas atomized Au—Ge alloy powder having a composition consisting of Au and inevitable impurities, with the remainder consisting of non-halogen flux , the non-halogen flux reducing solid active agent comprising a saccharide having 4-6 hydroxyl groups, highly viscous solvent comprising a compound having an isobornyl group, and, alkane diols, alkylene glycols, the group consisting of hydrocarbons, terpenes and ether more selected one or low viscosity solvent composed of two or more was an a u-Ge alloy solder paste Ru flux der mixed by blending a thixotropic agent.

The blending ratio of the reducing solid activator comprising saccharides having 4 to 6 hydroxyl groups contained in the non-halogen flux, the high-viscosity solvent comprising the compound having an isobornyl group, the low-viscosity solvent, and the thixotropic agent contained as required is as follows: Specifically, reducing solid activator composed of saccharide having 4 to 6 hydroxyl groups: 5 to 60% by mass, high viscosity solvent composed of compound having isobornyl group: 10 to 60% by mass, low viscosity solvent: 20 -70 mass%, thixotropic agent: 25 mass% or less .
(3) The halogen-free flux, reducing solid active agents comprising a saccharide having 4-6 hydroxyl groups: 5 to 60 wt%, high viscosity solvent comprising a compound having a isobornyl group: 10 to 60 mass%, low viscosity solvent : Ru fluxes der you containing 20 to 70 wt% a u-Ge alloy solder paste,
(4) The halogen-free flux, reducing solid active agents comprising a saccharide having 4-6 hydroxyl groups: 5 to 60 wt%, high viscosity solvent comprising a compound having a isobornyl group: 10 to 60 mass%, low viscosity solvent : containing 20 to 70 wt%, more thixotropic agent: is 25 wt% or less Ru fluxes der you containing a u-Ge alloy solder paste, the one having the characteristics.

The saccharide having 4 to 6 hydroxyl groups is specifically selected from the group consisting of erythritol, fructose, galactose, glucose, mannose, sorbitol, lactose, sucrose, xylitol, hexitol, maltitol, lactitol, ribitol and mannitol. is a kind of compound or a mixture of two or more were,
High viscosity solvent comprising a compound having the isobornyl group, specifically, wherein one or both either isobornyl cyclohexanol or isobornyl phenol,
The low-viscosity solvent includes a species selected from the group consisting of alkanediol, alkylene glycol, hydrocarbon, terpene, and ether, or two or more species.
(5) The saccharide having 4 to 6 hydroxyl groups is selected from the group consisting of erythritol, fructose, galactose, glucose, mannose, sorbitol, lactose, sucrose, xylitol, hexitol, maltitol, lactitol, ribitol and mannitol. A species compound or a mixture of two or more species,
The highly viscous solvent comprising the compound having an isobornyl group is either or both of isobornyl cyclohexanol and isobornyl phenol,
The low viscosity solvent, alkane diols, those with alkylene glycols, hydrocarbons, species selected from the group consisting of terpenes and ether or two or more including A u-Ge alloy solder paste, in the features.

The low-viscosity solvent includes alkanediol, alkylene glycol, hydrocarbon, terpene and ether, 2-ethyl-1,3-hexanediol, 1,5-pentanediol, 1,4-butanediol, triethylene glycol Tetraethylene glycol, tetradecane, a-terpineol, dibenzyl ether, p-dodecylphenol, 2-nonylphenol and 2-phenoxyethanol .
(6) The low viscosity solvent is 2-ethyl-1,3-hexanediol, 1,5-pentanediol, 1,4-butanediol, triethylene glycol, tetraethylene glycol, tetradecane, a-terpineol, dibenzyl ether, p- dodecylphenol, one or more including selected from the group consisting of 2-nonylphenol and 2-phenoxyethanol.

(7) thixotropic agent is that having the characteristics to Oh Ru A u-Ge alloy solder paste, a fatty acid amide.

The Au—Ge alloy powder used in the Au—Ge alloy solder paste of the present invention is an Au—Ge alloy having a composition containing Ge: 10.5 to 15.5% by mass, and the remainder consisting of Au and inevitable impurities. The molten metal obtained by melting was maintained at a temperature of 600 ° C. to 1000 ° C., and after mechanical stirring or mechanical stirring, the molten metal thus stirred was pressurized at a pressure of 300 to 800 kPa and an injection pressure of 5000 to 8000 kPa. It is manufactured by injecting an inert gas from a small diameter nozzle having a diameter of 1 to 2 mm under pressure and a nozzle gap of 0.3 mm or less. The stirring is preferably mechanical stirring, and propeller stirring is more preferable among mechanical stirring. Electric stirring such as electromagnetic stirring may be used in combination with the mechanical stirring. The rotational speed of mechanical stirring is not particularly limited, but is 60 to 100 r. p. It is preferable to stir the propeller at m for 3 to 10 minutes.
In the method for producing an Au—Ge alloy powder for solder paste of the present invention, when the Au—Ge alloy molten metal is mechanically stirred, an Au—Ge alloy molten metal having almost no segregation of the Ge phase is obtained. -Ge alloy molten metal is atomized, and the obtained atomized powder is subjected to sieve classification and wind classification to obtain an Au-Ge alloy powder having a particle size of 15 to 60 μm, and is composed of such an Au-Ge alloy powder and the non-halogen flux. When the solder paste is used, the number of voids generated in the brazed portion is reduced. In particular, the generation of large voids exceeding 25 μm is not observed, and the step of cleaning the brazed portion can be omitted.

  The reason why the content of Ge contained in the Au-Ge alloy powder for solder paste of the present invention is limited to 10.5 to 15.5% by mass is that this type of solder paste is soldered onto a substrate coated with Au plating. If the content of Ge contained in the Au-Ge alloy powder is less than 10.5% by mass, the Au of the Au plating coating is made of the brazing metal. It is not preferable because the Au-Ge alloy is eroded and the Au concentration is increased, the composition is changed, the melting point is increased and the melt viscosity is increased, and the gas generated during the melting of the paste is trapped in the vicinity of the substrate. If the Ge content exceeds 15.5% by mass, large voids exceeding 25 μm are generated, which is not preferable.

The “reducing solid activator containing a saccharide having 4 to 6 hydroxyl groups” contained in the non-halogen flux is a component that improves the wettability of the flux. The saccharide contained in the reducing solid activator having 4 to 6 hydroxyl groups is not preferable because the number of hydroxyl groups is less than 4 because the activity is insufficient and wettability is reduced. This is because if the number of hydroxyl groups exceeds 6, the molecular weight increases, the boiling point of the compound becomes too high, and a residue is formed after the soldering is completed, which is not preferable. The amount of the reducing solid activator containing a saccharide having 4 to 6 hydroxyl groups is preferably 5 to 60% by mass with respect to 100% by mass of the total flux. The reason is that if the amount of the reducing solid activator containing saccharides having 4 to 6 hydroxyl groups is less than 5% by mass, the activity is insufficient and the wettability is lowered, while the reducing solid activator is not preferred. When the content exceeds 60% by mass, it is difficult to handle the Au—Ge alloy solder paste obtained by mixing the Au—Ge alloy powder and the flux, and a residue is generated, which is not preferable. Is.

  The high-viscosity solvent containing the compound containing the isobornyl group has a high viscosity and is added to achieve a high viscosity of the flux. However, if the content is less than 10% by mass with respect to 100% by mass of the total flux, the viscosity and tackiness are insufficient, which is not preferable. On the other hand, the high-viscosity solvent containing a compound containing an isobornyl group exceeds 60% by mass. If it is contained, the Au—Ge alloy solder paste obtained by mixing the Au—Ge alloy powder and the flux exhibits a high viscosity, which makes it difficult to handle.

  The low-viscosity solvent is added for the purpose of adjusting the viscosity so that proper fluidity can be obtained. If the content of the low-viscosity solvent is less than 20% by mass with respect to 100% by mass of the total flux, it is not preferable because proper fluidity cannot be obtained. On the other hand, if the content exceeds 70% by mass, a residue is generated after the soldering is completed. This is because it is not preferable.

  Since the solder paste containing the Au—Ge alloy powder of the present invention does not generate a large void exceeding 25 μm in diameter, it is more reliable than the solder paste containing the conventional Au—Ge alloy powder. The paste can be provided, the defective product incidence rate of semiconductor devices can be reduced, the cost can be reduced, and the cleaning process can be omitted, which can contribute to the cost reduction, and has excellent industrial effects Is what it brings.

Example 1
The melt is melted in a high-frequency melting furnace, the propeller is rotated at 80 rpm for 3 minutes while the obtained molten metal is kept at 800 ° C., and the molten metal is mechanically stirred. The gas atomized powder is produced by dropping the molten metal from the nozzle and simultaneously injecting Ar gas from the gas nozzle provided around the nozzle so that the nozzle gap is 0.2 mm toward the molten metal. By sieving the powder with a sieve, gas atomized Au—Ge alloy powders A to O having an average particle size of 30 μm and having the composition shown in Table 1 were produced. Furthermore, Au—Ge alloy powder P having the component composition shown in Table 1 was produced by the rotating electrode method.

  Furthermore, commercially available Deltalux 527N (hereinafter referred to as non-halogen flux a) made of Senju Metal was prepared.

  Furthermore, erythritol, xylitolitol, sorbitol, ribitol is prepared as a reducing solid activator, and a mixed agent prepared by mixing at a ratio of isobornylcyclohexanol: isobornylphenol = 8: 2 as a highly viscous solvent. Alternatively, isobornylcyclohexanol is prepared, and tetraethylene glycol, 2-ethyl-1,3-hexanediol, 1,5-pentanediol, tetraethylene glycol, a-terpineol, and p-dodecylphenol are prepared as low-viscosity solvents. Further, stearic acid amide, erucic acid amide, oleic acid amide, and palmitic acid amide were prepared as thixotropic agents, and these were blended and mixed as shown in Table 2 to prepare non-halogen fluxes b to h.

The Au—Ge alloy powders A to P shown in Table 1 are mixed with the non-halogen fluxes a to h shown in Table 2 in proportions as shown in Table 3 and mixed, and then the present invention Au—Ge shown in Table 3 is mixed. Alloy solder pastes 1 to 13 and comparative Au—Ge alloy solder pastes 1 to 5 were prepared.
Furthermore, the conventional Au-Ge alloy which consists of Au-Ge alloy powder P shown in Table 1 produced by the rotating electrode method: 94.5 mass%, paraffin wax: 2.2 mass%, liquid paraffin: 3.3 mass% A solder paste was prepared and prepared.

Next, a plate made of an Fe—Ni-based alloy (Ni: 42%, an alloy composed of the remaining Fe and inevitable impurities) having dimensions of 10 mm in length, 10 mm in width, and 1 mm in thickness is prepared. The surface of the alloy plate was plated with Ni having a thickness of 2.5 μm and then plated with Au having a thickness of 0.03 μm, and this plated plate was prepared as a substrate.
The Au—Ge alloy solder pastes 1 to 13 of the present invention, the comparative Au—Ge alloy solder pastes 1 to 5 and the conventional Au—Ge alloy using a mask having a diameter of 6.5 μm and a thickness of 1.2 mm on the substrate. After the solder paste is printed and reflowed (preheat 150 ° C./60 seconds + main heat 320 ° C./60 seconds), the number of voids having a size of 25 μm or more is obtained using a transmission X-ray apparatus and image processing software. Are shown in Table 3.
Furthermore, the presence or absence of residue in the soldered portion was observed, and the results are shown in Table 3.

From the results shown in Tables 1 to 3, the Au—Ge alloy solder pastes 1 to 13 of the present invention have fewer voids than the conventional Au—Ge alloy solder paste, and the conventional Au—Ge alloy solder paste has a thickness of 25 μm. It can be seen that the voids exceeding 25 μm are not generated in the Au—Ge alloy solder pastes 1 to 13 of the present invention, and there is no residue, whereas the large voids exceeding are generated.
However, in the comparative Au—Ge alloy solder pastes 1 to 5 that deviate from the conditions of the present invention, the Au—Ge alloy powder contained in the Au—Ge alloy solder paste is not melted even if voids are generated or melted. It turns out that it is not preferable.

Claims (7)

Ge: 10.5-15.5 contains by mass%, the remainder containing 80 to 95 wt% of the gas atomization Au-Ge alloy powder having a composition consisting of Au and unavoidable impurities, Ri Do the balance is non-halogen flux,
The non-halogen flux comprises a reducing solid activator comprising a saccharide having 4 to 6 hydroxyl groups, a highly viscous solvent comprising a compound having an isobornyl group, and a group comprising alkanediol, alkylene glycol, hydrocarbon, terpene and ether. selected one or low viscosity solvents of two or more is a flux added and mixed to you wherein a u-Ge alloy solder paste. Ge: 10.5 to 15.5% by mass, the remainder containing 80 to 95% by mass of gas atomized Au—Ge alloy powder having a composition consisting of Au and inevitable impurities, and the balance consisting of non-halogen flux,
The halogen-free flux, reducing solid active agent comprising a saccharide having 4-6 hydroxyl groups, highly viscous solvent comprising a compound having an isobornyl group, and, alkane diols, alkylene glycols, of hydrocarbon, the group consisting of terpenes and ether selected one or of two or more low viscosity solvent agent, you wherein a further flux added and mixed thixotropic agent a u-Ge alloy solder paste. The halogen-free flux, with respect to the total mass flux, the reducing solid active agent: 5 to 60 wt%, the high-viscosity solvent: 10 to 60 wt%, the low-viscosity solvent: by blending 20 to 70 wt% The Au-Ge alloy solder paste according to claim 1, which is a mixed flux. The halogen-free flux, with respect to the total mass flux, the reducing solid active agent: 5 to 60 wt%, the high-viscosity solvent: 10 to 60 wt%, the low-viscosity solvent: 20 to 70 wt%, further said thixotropic 3. An Au—Ge alloy solder paste according to claim 2 , wherein the flux is a mixture of 25% by mass or less of an agent. Before SL sugar acids include erythritol, fructose, galactose, glucose, mannose, sorbitol, lactose, sucrose, xylitol, hexitol, maltitol, lactitol, selected from the group consisting of ribitol and mannitol one compound or two or more A mixture of
Before SL highly viscous solvents, isobornyl cyclohexanol or isobutanol one isobornyl either phenol or Au-Ge alloy solder paste according to any one of claims 1 to 4, characterized in that its both. The low-viscosity solvent is 2-ethyl-1,3-hexanediol, 1,5-pentanediol, 1,4-butanediol, triethylene glycol, tetraethylene glycol, tetradecane, a-terpineol, dibenzyl ether, p The Au-Ge alloy solder paste according to any one of claims 1 to 5, comprising one or more selected from the group consisting of -dodecylphenol, 2-nonylphenol and 2-phenoxyethanol. The Au-Ge alloy solder paste according to claim 2 or 4, wherein the thixotropic agent is a fatty acid amide.