JP2017165610A - Lead free low melting point composition, encapsulation material, and encapsulation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead free low melting point composition which exhibits no flowability in a temperature range of 225°C or less and can encapsulate a target in a temperature range of no more than 300°C.SOLUTION: There is provided a low melting point composition containing Ag, P, I and O as essential constitutional elements, having a percentage of a compound, where the composition is represented as an aggregate of various compounds represents by the formula MQwith cation and anion bound, where M is cation with valency of m and Q is anion with valency of q, and all anions other than oxide ion (O) bind to Ag ion satisfying the following condition:AgI:20 to 85 mol%, AgO:15 to 50 mol%, PO:4 to 18 mol%, ΣAgQ:80 to 96 mol%, ΣMO:15 to 70 mol%, and (ΣMO-AgO)/AgO:0.3 to 0.65 (mol/mol) and containing practically no PbO, AgF nor AgCl.SELECTED DRAWING: None

Description

  The present invention relates to the field of inorganic compositions, and more specifically to a lead-free low melting point composition, a lead-free low melting point sealing material comprising the composition, and a sealing method using the same.

  Various low melting point compositions are used in various applications in the electrical and electronic equipment industry. For example, in the sealing of electrical / electronic parts such as crystal resonators and LED elements, a low melting point Au—Sn alloy solder paste or glass frit for sealing is applied to these parts and fired. It is used.

  The Au-Sn alloy (Patent Document 1) is a material that has been used for a long time and is reliable, but it is very expensive because it contains gold as a component.

For this reason, it is known to use a PbO-based or V ₂ O ₅ -based low melting glass for the preparation of the sealing material. For example, PbO-based glass that can be sealed at a temperature of less than 400 ° C. is disclosed in Patent Document _{2, and} V ₂ O ₅ glass that can be fired at 350 ° C. or less is disclosed in Patent Document 3.

  On the other hand, a sealing material that can be used at 300 to 330 ° C., which contains an oxide of silver oxide and / or silver halide and another metal (which may be Pb or V) is also known (Patent Document 4). ).

  Furthermore, a sealing material containing silver oxide, phosphorus pentoxide and silver iodide is also known (Patent Documents 5 and 6).

  Under such circumstances, reflow soldering using lead-free solder (Sn—Ag—Cu, melting point 217 to 219 ° C.) as the circuit configuration of electric / electronic materials is increasingly miniaturized in recent years. Lead-free encapsulants that are compatible with both low melting point and heat resistance have been demanded, but the demand has not been fully met.

JP-A-9-122969 JP-A-61-261233 JP 2013-32255 A JP-A-5-147974 JP 2000-183560 A JP 2001-328837 A

  The object of the present invention is to apply to a sealing object having a surface made of an inorganic oxide or a metal, and when heated in the atmosphere, it does not exhibit fluidity in a temperature range of 225 ° C. or lower, but does not exceed 300 ° C. Lead-free low melting point composition that can be spread and flowed well, and then cooled and solidified so that it can be tightly adhered (adhered) to the surface of the object to be sealed and sealed It is providing the sealing material containing a low melting-point composition, and the sealing method using the same.

  The present inventor believes that a composition containing Ag, P, O, and I in a proportion within a predetermined range does not flow at 225 ° C. while having a low melting point not exceeding 300 ° C., and meets the above purpose. I found. The present invention has been completed by further studies based on this finding. That is, the present invention provides the following.

1. A low-melting-point composition comprising Ag, P, I, and O as essential components, wherein a cation and an anion are bonded to each other, a formula MQ _{m / q} [wherein M is a valence m Cation and Q represent an anion having a valence of q. When the anion other than the oxide ion (O ²⁻ ) is all bound to the Ag ion, the proportion of these compounds is as follows:
AgI: 20-85 mol%,
AgO _1/2 ... 15-50 mol%,
PO _5/2 ... 4-18 mol%,
ΣAgQ _{1 / q} ·· 80-96 mol%,
ΣMO _{m / 2} ... 15 to 70 mol%, and (ΣMO _{m / 2} −AgO _1/2 ) / AgO _1/2 ... 0.3 to 0.65 (mol / mol)
And substantially free of PbO, AgF and AgCl.
Low melting point composition.
2. The low-melting-point composition according to 1 above, which is substantially free of alkali metal oxides.
3. A low-melting-point sealing material comprising the lead-free low-melting composition according to 1 or 2 above.
4). A sealing method for a sealing target, comprising: preparing a sealing target; applying the lead-free low melting point sealing material of 3 above to the surface of the sealing target; and heating the low melting point sealing material by heating Fluidizing and then allowing to cool and solidify.
5. 4. The sealing method according to 4 above, wherein the heating is performed in an atmosphere containing oxygen.
6). The sealing method according to claim 4 or 5, wherein the surface to be sealed to which the low-melting-point sealing material is applied is composed of a metal or an inorganic oxide.

  The low melting point composition according to 1 of the present invention is obtained by applying a low melting point sealing material containing the composition to the surface to be sealed, in a wide temperature range not exceeding 300 ° C. in the atmosphere, for example, preferably 230 to 300 ° C, more preferably 250 to 300 ° C, and even more preferably 250 to 275 ° C, by heating and spreading appropriately, then cooling and solidifying to adhere to the surface made of inorganic oxide or metal to be sealed Sealing with good properties can be achieved. Moreover, since the low melting point sealing material does not flow at 225 ° C. or lower, and preferably does not soften, lead-free solder (Sn—Ag—Cu, melting point 217˜ Reflow soldering using 219 ° C.) is allowed.

  In the present specification, the term “low melting point” means that the melting point does not exceed 300 ° C., more preferably the melting point is in the range of 250 to 300 ° C., more preferably in the range of 250 to 275 ° C. means.

In defining the composition of the present invention by its components and their quantitative relationship, for convenience, the composition is formed by combining a cation and an anion derived from the raw material for production, with the formula MQ _{m / q} [wherein M Represents a cation having a valence of m, and Q represents an anion having a valence of q. And anions other than oxide ions (O ²⁻ ) are all considered to be bonded to Ag ions. Note that, under the above quantitative conditions satisfied by these compounds, a relationship of [number of moles of Ag ions]> [number of moles of each anion other than oxide × total number of valences] is established.

  The low melting point composition of the present invention has a good flowability (flowing) at a temperature not exceeding 300 ° C., for example, preferably in the range of 230 to 300 ° C., more preferably 250 to 300 ° C., and further preferably 250 to 275 ° C. It has the property of being easy to spread). Therefore, the composition is applied to a sealing object having a surface made of an inorganic oxide or a metal, for example, in the form of particles (for example, powder or paste), and heated to the above temperature to be sealed. By spreading on the surface of the object and then cooling and solidifying it, it can be sealed tightly to the surface of the object to be sealed.

  In the composition of the present invention, AgI is an essential component and has the effect of lowering the liquidus temperature of the composition and the effect of forming a glass phase. In order to utilize these effects, the content of AgI is preferably 20 to 85 mol%, more preferably 23 to 82 mol%, still more preferably 40 to 80 mol%.

AgO _{1/2 is} also an essential component of the composition of the present invention. AgO _1/2 supplies oxide ions (O ²⁻ ) to cations M ^{m +} (mainly P ⁵⁺ ) other than Ag ⁺ , and the coordination number of M ^{m +} and MO _n ^{(2n−m) −} coordination polyhedron By changing the number of connections, an effect of forming a liquid phase or a glass phase of the composition and an effect of improving the adhesion with the oxide are produced. In order to utilize these effects, the content of AgO _1/2 is preferably 10 to 55 mol%, more preferably 13 to 52 mol%, and still more preferably 15 to 45 mol%.

PO _{5/2 is} also an essential component of the composition of the present invention, and has the effect of lowering the liquidus temperature of the composition, the effect of forming a glass phase, and the effect of increasing the adhesion with inorganic oxides. . For use of these effects, the content of PO _5/2 is preferably 4 to 18 mol%, more preferably 4.5 to 17 mol%. Furthermore, a more preferred upper limit for allowing no softening at 225 ° C. is 12.5 mol%.

In order for the composition of the present invention not to flow at 225 ° C but to flow in the range of 250 to 300 ° C, the total content of all compounds including Ag (ΣAgQ _{1 / q} ) is preferably Is 80 to 96 mol%. Furthermore, in order to make it possible to prevent softening at 225 ° C., ΣAgQ _{1 / q} is preferably 85 to 95 mol%.

In the composition of the present invention, the total content of the oxide components represented by MO _{m / 2} (ΣMO _{m / 2 is} not allowed to flow at 225 ° C. but to flow in the range of 250 to 300 ° C. ) Is preferably 15 to 70 mol%. Further, ΣMO _{m / 2} is preferably set to 20 to 60 mol% in order to enable 225 ° C. not to be softened.

In the composition of the present invention, in order to stabilize the liquid phase and the glass phase by adjusting the coordination number of the cation M ^{m +} and the number of linkages of MO _n ^{(2n−m) −} coordination polyhedron, (ΣMO _{m / 2} The value calculated by −AgO _1/2 ) / AgO _1/2 is preferably 0.3 to 0.65 (mol / mol), and more preferably 0.32 to 0.61. Furthermore, in order to enable the softening at 225 ° C., the value calculated by (ΣMO _{m / 2} −AgO _1/2 ) / AgO _1/2 should be 0.33 to 0.38. preferable.

  PbO is harmful to the environment, and a low melting point composition containing PbO cannot be used in a reflow process using lead-free solder. In this respect, since the composition of the present invention does not substantially contain PbO, there is no such problem. Here, “substantially does not contain” PbO means that the content is 0.1 mol% or less even when it is mixed in a trace amount as an impurity.

  Furthermore, the composition of the present invention is substantially free of AgF and AgCl. Here, “substantially free” of AgF and AgCl means that the total content thereof is 0.1 mol% or less even when they are mixed in a trace amount as impurities.

  The composition of the present invention may contain AgBr as an optional component. When this composition contains AgBr, the wettability of the composition with respect to the metal material is improved without causing corrosion of the metal material. The Br anion has the effect of increasing the solidus temperature of the composition. When the operating temperature of the electronic component to be sealed is in a high temperature range, it is necessary to increase the heat resistance of the sealing material. In such a case, the composition of the present invention should contain Br anion. Is useful, and the solidus temperature can be adjusted accordingly. The Br anion is substituted and dissolved in AgI, thereby promoting the melting of the composition of the present invention in the sealing process. When AgBr is contained, its content is preferably 0.1 mol% or more, more preferably 1 mol% or more, still more preferably 5 mol% or more, and particularly preferably 10 mol in terms of improving wettability. % Or more. On the other hand, the content is preferably 20 mol% or less, more preferably 12 mol% or less, still more preferably 8 mol% or less, particularly preferably 5 mol% or less from the viewpoint that the solidus temperature is not excessively raised. It is.

The composition of the present invention may contain AgS _1/2 as an optional component. AgS _1/2 has an effect of lowering the liquidus temperature of the composition and an effect of forming a glass phase if contained in a small amount, but if contained in a large amount, it may increase the liquidus temperature conversely. There is. Therefore, even when AgS _1/2 is contained, the content is preferably 20 mol% or less, more preferably 12 mol% or less, still more preferably 8 mol% or less, and particularly preferably 5 mol% or less. .

The composition of the present invention may contain MoO ₃ as an optional component. MoO ₃ has an effect of lowering the liquidus temperature of the composition of the present invention and an effect of forming a glass phase if contained in a small amount, but if it is contained in a large amount, the liquidus temperature is raised reversely. There is a fear. Therefore, even if the inclusion of MoO _3, the content thereof is preferably 0.1 to 20 mol%, more preferably 1 to 15 mol%, more preferably 2 to 13 mol%.

The composition of the present invention may contain WO ₃ as an optional component. WO ₃ has an effect of lowering the liquidus temperature of the composition of the present invention and an effect of forming a glass phase if contained in a small amount. However, if contained in a large amount, WO ₃ may increase the liquidus temperature conversely. There is. Therefore, even if the inclusion of WO _3, the content of WO ₃ is preferably 0.1 to 20 mol%, more preferably 1 to 15 mol%, more preferably 2 to 13 mol%.

  The composition of the present invention may contain ZnO as an optional component. ZnO has an effect of lowering the liquidus temperature of the composition of the present invention and an effect of forming a glass phase if contained in a small amount, but if contained in a large amount, ZnO may increase the liquidus temperature conversely. is there. For this reason, even when ZnO is contained, its content is preferably 0.1 to 20 mol%, more preferably 1 to 15 mol%, still more preferably 2 to 13 mol%.

The composition of the present invention may contain BO _3/2 as an optional component. BO _3/2 has the effect of lowering the liquidus temperature of the composition of the present invention and the effect of forming a glass phase if it is contained in a small amount, but if it is contained in a large amount, it increases the liquidus temperature on the contrary. There is a risk of causing. Even when BO _3/2 is contained, the content is preferably 0.1 to 20 mol%, more preferably 1 to 15 mol%, and still more preferably 2 to 13 mol%.

The composition of the present invention may contain GeO ₂ as an optional component. If GeO ₂ is contained in a small amount, it has the effect of lowering the liquidus temperature of the composition of the present invention and the effect of forming a glass phase, but if it is contained in a large amount, the water resistance may be deteriorated. Therefore, even if the inclusion of GeO _2, the content is preferably 0.1 to 20 mol%, more preferably 1 to 15 mol%, more preferably 2 to 13 mol%.

The composition of the present invention may contain SnO ₂ as an optional component. If SnO ₂ is contained in a small amount, it has an effect of lowering the liquidus temperature of the composition of the present invention and an effect of forming a glass phase. However, if contained in a large amount, SnO ₂ may increase the liquidus temperature conversely. There is. For this reason, even when SnO ₂ is contained, the content thereof is preferably 0.1 to 20 mol%, more preferably 1 to 15 mol%, and further preferably 2 to 13 mol%.

The composition of the present invention may contain SbO _3/2 as an optional component. If SbO _3/2 is contained in a small amount, it has an effect of forming a glass phase of the composition of the present invention. However, if contained in a large amount, SbO _3/2 may increase the liquidus temperature. For this reason, even when SbO _3/2 is contained, the content is preferably 0.1 to 20 mol%, more preferably 1 to 15 mol%, and still more preferably 2 to 13 mol%.

The composition of the present invention may contain BiO _3/2 as an optional component. BiO _3/2 has an effect of forming a glass phase of the composition of the present invention if contained in a small amount, but if contained in a large amount, it may cause an increase in liquidus temperature. For this reason, even when BiO _3/2 is contained, the content is preferably 0.1 to 20 mol%, more preferably 1 to 15 mol%, and still more preferably 2 to 13 mol%.

The composition of the present invention may contain TeO ₂ as an optional component. TeO ₂ has an effect of forming a glass phase of the composition of the present invention if contained in a small amount, but if contained in a large amount, TeO ₂ may increase the liquidus temperature. For this reason, even when TeO ₂ is contained, the content is preferably 0.1 to 20 mol%, more preferably 1 to 15 mol%, and still more preferably 2 to 13 mol%.

The composition of the present invention may contain CuO _1/2 as an optional component. If CuO _1/2 is contained in a small amount, it has an effect of forming a glass phase of the composition of the present invention. However, if contained in a large amount, CuO _1/2 may increase the liquidus temperature. For this reason, even when CuO _1/2 is contained, the content is preferably 0.1 to 20 mol%, more preferably 1 to 15 mol%, and still more preferably 2 to 13 mol%.

The composition of the present invention may contain VO _5/2 as an optional component. VO _5/2 has an effect of lowering the liquidus temperature of the composition of the present invention and an effect of forming a glass phase if it is contained in a small amount, but if it is contained in a large amount, the water resistance may be deteriorated. . Therefore, even when VO _5/2 is contained, the content thereof is preferably 0.1 to 20 mol%, more preferably 1 to 15 mol%, and further preferably 2 to 13 mol%.

When the alkali metal oxide RO _1/2 is present in the composition of the present invention, the water resistance may be lowered. For this reason, it is preferable that RO _1/2 is not substantially included. Here, “substantially free” of RO _1/2 means that the total content thereof is 0.1 mol% or less even when they are mixed in a trace amount as impurities.

  The composition of the present invention may be provided in the form of a mixture of various raw material reagent powders prepared in advance so as to give the desired low melting point composition by heating and melting. Moreover, it can also be set as the form in which the solid solution, double halide, and glass phase which are obtained by heating, melting, and cooling such a mixture are formed. When a solid solution, a double halide, or a glass phase is formed, it becomes a composition that can be easily softened and melted by heating in a shorter time, and therefore, such a composition is more preferable.

  The composition of the present invention can also be produced by preparing a plurality of aqueous solutions containing an appropriate combination of cations and anions contained in the product, mixing them, reacting them, and collecting the precipitate. Can do.

The composition of the present invention can be processed into powder, beads, sheets, rods, etc. and used as a sealing material. From the viewpoint of improving workability, it can be mixed with water, an organic solvent, a dispersant, a thickener and the like and used as a paste-like sealing material. As the organic solvent, terpineol, cellosolve, isobornylcyclohexanol and the like can be used. In addition, from the viewpoint of improving various characteristics or adding performance, a form including a filler can also be used. For example, in order to impart conductivity, it may be in a form containing a conductive filler such as a metal (for example, metallic silver) or carbon nanotube, and high in order to impart thermal conductivity. It can be of a form containing a filler having thermal conductivity (for example, aluminum nitride, silicon carbide, etc.), and in order to suppress thermal expansion, it is a non-alkali filler with a low thermal expansion coefficient ( For example, quartz glass, ZrW ₂ O ₈ , manganese nitride, Bi _0.95 La _0.05 NiO ₃ or the like may be used. These fillers may be blended as a part of the composition of the present invention in accordance with the performance required according to the use mode / use environment of the sealing object in which the composition of the present invention is used. However, these fillers are consistently used in the manufacturing process of the composition of the present invention, in the heat treatment for sealing, and also in the usage environment of the target to be sealed (electronic equipment, etc.) after sealing. Since it is a solid particle and does not affect the composition of parts other than the filler, the positive or negative ionic valence of the atoms constituting the filler is not involved in the definition of the composition of the present invention.

  When the composition of the present invention is used for sealing, the surface to be sealed can be composed of various metals and nonmetals (such as inorganic oxides).

  When the composition of the present invention is used for sealing, the working atmosphere may be in the presence or absence of oxygen. Therefore, since the sealing step with the composition of the present invention can be performed in the air, adjustment of the atmosphere is unnecessary, which is preferable in terms of simple operation. At the time of sealing, pressure can be applied to the object to be sealed to further improve the adhesion, and vibration such as ultrasonic waves can be applied to the sealing material to promote softening and melting.

  Hereinafter, the features of the present invention will be described more specifically with reference to examples. However, the present invention is not intended to be limited to these examples.

[Example 1]
In order to obtain the composition shown in the column of Example 1 in Table 1, using AgI, AgO _1/2 and PO _5/2 as raw materials, the raw materials are weighed to a total of 5 g, and pulverized and mixed in a mortar. To powder. 5 g of the produced powder was put in a magnetic crucible. The crucible was placed in a furnace heated to 600 ° C. in the atmosphere as shown in Table 1, and held for 20 minutes. The dissolved contents were poured onto a graphite plate at room temperature to obtain a bulk. The rapidly cooled bulk was pulverized with a mortar to obtain a composition of the present invention.

[Examples 2-11, Comparative Examples 1-7]
A powder was obtained in the same manner as in Example 1 except that part of the production conditions were changed to the conditions shown in Tables 1 to 3, and used as the composition of the present invention.

[Evaluation of physical properties]
1. Evaluation of flowability 0.04 g of the composition powder of any of Examples 1 to 11 and Comparative Examples 1 to 7 is placed on one of two glass plates (soda lime glass) of 25 mm square and 1.3 mm thickness. The other glass plate was overlaid on top. Those glass plates stacked with the powder in between were placed in an electric furnace. The temperature was raised to a predetermined temperature (specific temperature between 200 ° C. and 300 ° C.) at 5 ° C./min, then held at the same temperature for 1 hour, heating was stopped and cooling was performed. The overlapping glass plates taken out from the furnace were visually observed, and the flowability was evaluated according to the following criteria.

<Flowability evaluation method>
(A) The shape of the particles before heating is maintained, and the particles are not joined together. : Not softened (b) Particles are partly joined, but there are many voids in the powder. : Softened (c) The whole powder is melted to form a film having a uniform thickness with almost no voids. : Flowed (1) It did not soften at 225 ° C or lower, and flowed at any temperature of 250 to 300 ° C. : Good (2) Softened at 225 ° C but did not flow, but flowed at any temperature of 250 to 300 ° C. : Possible (3) It flowed at 225 ° C. or lower, or did not flow at any temperature of 300 ° C. or lower. : Impossible

<Result>
The evaluation results are shown in Tables 1-3.

  As shown in Tables 1 and 2, the compositions of Examples 1 to 11 did not flow by heat treatment at 225 ° C or lower temperature (200 ° C), and any temperature of 250 to 300 ° C. Then it flowed. On the other hand, any composition of the comparative example flowed at a temperature of 225 ° C. as shown in Tables 2 to 3, or was not flowed even at 300 ° C.

The low-melting-point composition of the present invention can be used for reflow soldering using lead-free solder in the sealing of crystal resonators, LED elements, and other various electrical and electronic components. It is useful in that.

Claims (6)

A low-melting-point composition comprising Ag, P, I, and O as essential components, wherein a cation and an anion are bonded to each other, a formula MQ _{m / q} [wherein M is a valence m Cation and Q represent an anion having a valence of q. When the anion other than the oxide ion (O ²⁻ ) is all bound to the Ag ion, the proportion of these compounds is as follows:
AgI: 20-85 mol%,
AgO _1/2 ... 15-50 mol%,
PO _5/2 ... 4-18 mol%,
ΣAgQ _{1 / q} ·· 80-96 mol%,
ΣMO _{m / 2} ... 15 to 70 mol%, and (ΣMO _{m / 2} −AgO _1/2 ) / AgO _1/2 ... 0.3 to 0.65 (mol / mol)
And substantially free of PbO, AgF and AgCl.
Low melting point composition.   The low melting point composition according to claim 1, which is substantially free of alkali metal oxide.   A low melting point sealing material comprising the lead-free low melting point composition according to claim 1 or 2.   A sealing method for a sealing target, comprising: preparing a sealing target; applying the lead-free low melting point sealing material of claim 3 to the surface of the sealing target; and heating the low melting point sealing material And then allowing to cool and solidify by cooling.   The sealing method according to claim 4, wherein the heating is performed in an atmosphere containing oxygen. The sealing method according to claim 4 or 5, wherein the surface to be sealed to which the low-melting-point sealing material is applied is composed of a metal or an inorganic oxide.