TWI552825B - A solder paste composition, a solder paste and a soldering flux - Google Patents

Description

Solder paste composition, solder paste and flux

The present invention relates to a solder paste composition, a solder paste and a flux.

The solder paste is a paste solder material which is homogeneously mixed by alloy solder powder and paste flux. The alloy solder powder most commonly used at present includes Sn-Ag-based, Sn-Pb-based, Sn-Sb-based, Sn-Cu-based, Sn-Bi-based, and Sn-Ag-Cu-based alloys. The flux typically comprises or consists of a resin, a thixotropic agent, an activator, a solvent, and optionally other additives. Flux is a key material for purifying metal surfaces, improving wettability, preventing oxidation of solder materials, ensuring solder paste quality, and/or superior processes for such materials. In addition, the flux has an important influence on the storage stability of the solder paste.

Under normal circumstances, the solder paste hardens or solidifies over time during storage. The storage stability of the solder paste is usually measured by the speed of hardening or solidification. Solder pastes have a high storage stability and generally harden or solidify slowly; conversely, solder pastes have a low storage stability, which exhibits faster hardening or solidification characteristics.

In the existing solder paste, an organic acid, an organic amine small molecule or a halogen-containing compound is used as an activator. The activator interacts with the alloy solder powder during solder paste storage, thus affecting its rheology and other properties. Please note that the above activators can seriously reduce the storage stability of the solder paste.

Regardless of the state of the art, the present invention contemplates providing a flux, a solder paste composition, and a solder paste to overcome the interaction of the activator present in the solder paste with the alloy solder powder during solder paste storage, thereby reducing soldering Technical problems with paste storage stability.

The solder paste of the present invention has excellent soldering properties and also has a high storage stability.

The solder paste of the present invention can significantly improve its storage stability by adding a long chain thiol and/or an organic chelating agent to the flux.

Accordingly, the present invention is directed to a flux comprising or consisting of a resin, a thixotropic agent, an activator, a solvent, and a long chain thiol and/or an organic chelating agent.

The terms "resin", "thixotropy", "activator", "solvent", "long-chain thiol" or "organic chelating agent" mean that one or more than one of the ingredients may be present in the present invention. In the flux.

In the present invention, the long-chain thiol is a compound having at least one -SH functional group having a carbon chain length of greater than or equal to 7 carbon atoms, wherein the carbon atoms are preferably covalently bonded to each other. . In a specific embodiment, the long chain thiol is selected from the group consisting of one or more compounds of the formula R(CH ₂ ) _n SH wherein R is methyl, carboxyl, or hydroxyl ( Hydroxyl), formyl or amido, n is 7 to 21, preferably 12 to 18; more preferably, the long chain thiol is hexanethiol, octyl A mixture of octanethiol, decanethiol, dodecanethiol, octadecanethiol, and/or the like is selected. Mixtures of different long chain thiols can also be used in the flux of the present invention.

In the present invention, the organic chelating agent is preferably selected from the group consisting of o- naphthisodiazine chelating agents. More preferably those, the organic chelating agent is selected from 1,10 - phenanthroline (1-10- o -naphthisodiazine), 2,9- dimethyl-4,7-diphenyl-1,10 -2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, 4,7-dimethyl-1,10- o -phenanthroline (4,7-dimethyl-1) , 10- o -naphthisodiazine), 4,7- diphenyl-1,10 - phenanthroline (4,7-diphenyl-1,10- o -naphthisodiazine ) and / or mixtures of the like.

In the present invention, the content of the long-chain thiol and/or organic chelating agent is an appropriate content for forming a single-molecular protective film on the surface of the alloy solder powder particles, which does not affect other performances of the solder paste. Preferably, the long chain thiol and/or organic chelating agent is present in an amount of from 0.2% by weight to 10% by weight, more preferably from 0.5% by weight to 5% by weight, based on the total of the flux. When the amount is less than 0.2% by weight, the formation of the monomolecular protective film on the surface of the alloy solder powder particles may be incomplete; when the amount is more than 10% by weight, the long-chain mercaptan and/or the organic chelating agent may adversely affect other properties of the solder paste. Such as welding performance or printing performance.

In one embodiment, the flux comprises a mixture of at least one long chain thiol of the invention and at least one organic chelating agent of the invention.

In the present invention, the resin is selected from the group consisting of rosin resins, acid modified rosin resins, hydrogenated rosin resins, disproportionated rosin resins, and/or polymeric rosin resins. (polymerized rosin resins), and/or mixtures thereof. The resin content can be a conventional amount in the art. Preferably, the resin is present in an amount of from 10% by weight to 60% by weight based on the total amount of the flux, and more preferably in an amount of from 30% by weight to 55% by weight.

Furthermore, the flux of the present invention comprises at least one thixotropic agent. The thixotropic agent is selected from the group consisting of polyamides, hydrogenated castor oils and/or amide modified hydrogenated castor oils, and/or mixtures thereof . The thixotropic agent level can be a conventional amount in the art. Preferably, the thixotropic agent is present in an amount of from 1% by weight to 10% by weight based on the total amount of the flux.

Another component of the flux of the present invention is at least one activator. The activator is selected from the group consisting of halogen-containing compounds, organic acid compounds, and/or organic amine compounds, and/or mixtures thereof. The activator content can be a conventional amount in the art. Preferably, the activator is present in an amount of from 0.5% by weight to 30% by weight based on the total amount of the flux.

Another component of the flux of the present invention is at least one solvent. In one embodiment, the solvent is a diol monoether and/or a diol diether solvent, such as diethylene glycol monohexyl ether and/or poly Polyethylene glycol dibutyl ether or the like. The solvent content can be a conventional amount in the art. Preferably, the solvent is present in an amount of from 10% to 60% by weight based on the total amount of the flux.

The flux of the present invention also contains other conventional additives such as plasticizers and/or antioxidants.

The flux of the present invention may be in the form of a mixture of all components, or may be in the form of a multi-container package or kit, wherein each component is contained in a separate container or a plurality of components assembled in one or more containers.

In the present invention, the flux can be prepared by conventional methods in the art, for example, by heating and mixing each component.

The invention also relates to a solder paste composition comprising the flux of the invention and at least one alloy solder powder. The alloy solder powder is selected from a lead-free alloy solder powder or a lead-containing alloy solder powder. The term "lead-free alloy solder powder" means that the alloy solder powder does not substantially contain lead, which means that the lead content is less than 5 wt%, preferably less than 1 wt%, based on the total amount of the alloy solder powder. More preferably less than 0.01 wt%.

Preferably, the volume ratio of the flux to the alloy solder powder is from 0.8:1 to 1.2:1. The lead-free solder powder is preferably selected from the group consisting of Sn-Ag-Cu, Sn-Ag, Sn-Cu, Sn-Zn, and/or Sn-Bi alloys. The lead-containing solder powder is preferably a Sn-Pb-based alloy. The alloy solder powder is preferably in the form of a spherical powder, wherein the spherical powder preferably has an average particle size of from 1 μm to 45 μm.

In the present invention, the term "average particle size" refers to a D ₅₀ value of a cumulative volume distribution curve in which 50% of the particle volume diameter is smaller than the stated value. The average particle size or a D ₅₀ value of the present invention by a laser diffraction-based assay (laser diffractometry) was measured, which is preferably measured using a Malvern 2000 from Malvern Instruments Limited Mastersizer. In this technique, the particle size dissolved in the suspension or emulsion is determined by diffraction of a laser beam based on the application of the Fraunhofer or Mie theory. In the present invention, the system using the Mie theory or Mie theory amended measure non-spherical particles, the average particle size and D ₅₀ values based or scattering measurements using, its angle relative to the incident laser beam of 0.02 to 135 degrees.

In the present invention, the solder paste composition is in the form of a multi-container package or kit in which each component is contained in a separate container or a plurality of components assembled in one or more containers. In a specific embodiment, the solder paste composition comprises at least two containers. The long chain mercaptan and/or organic chelating agent is used as the first part, and the alloy solder powder is used as the second part. The two parts are preferably not stored in the same container to avoid any physical or chemical contact. For example, the solder paste composition is in the form of a two-container package in which one container contains a flux and the other container contains an alloy solder powder. In another embodiment, the solder paste composition is in the form of a three-container package, wherein one container contains a long-chain thiol and/or an organic chelating agent, and the other container contains other components of the flux of the present invention, and The third container contains alloy solder powder.

The invention also relates to a solder paste which is a mixture of all of the components of the solder paste composition of the present invention.

In the solder paste of the present invention, the entire particle surface of the alloy solder powder is preferably covered with a monomolecular film. The monomolecular film is self-assembled and assembled from one or more long chain thiols and/or organic chelating agents.

The solder paste of the present invention also contains conventional additives such as plasticizers and/or antioxidants and the like.

The solder paste of the present invention can be prepared by mixing the flux of the present invention and an alloy solder powder.

The solder paste storage temperature is preferably from 0 ° C to 5 ° C to provide a high storage stability during long-term storage.

The examples of the present invention show that the solder paste of the present invention preferably has a viscosity change of less than ± 6% when stored at 30 ° C for 4 days. In contrast, the traditional solder paste has an 84.1% increase in viscosity compared to storage conditions. It is pointed out that the solder paste of the present invention has an excellent storage stability.

The storage stability of the solder paste of the invention is remarkably increased, and has better storage properties and excellent soldering properties. Compared with the existing solder paste, the solder paste of the present invention can be prepared by a simple preparation step.

All materials and reagents used in the present invention are commercially available unless otherwise stated.

Preparation of flux:

The solvent, resin, activator and thixotropic agent of the present invention are added to a stainless steel reaction vessel in proportion. The mixture was stirred at 100 ° C to 150 ° C until all ingredients were completely dissolved. Thereafter, the mixture is rapidly cooled, and a portion of the volatilized solvent is added and stored in a sealed manner.

Preparation of solder paste:

11.5 wt% flux and 88.5 wt% alloy solder powder were placed in a double planetary stirrer, heterogeneously stirred at room temperature, and dispensed in a 500 gram solder paste jar.

Example 1

In this embodiment, 88.5 wt% of the alloy solder powder Sn-3.0Ag-0.5Cu, and 11.5 wt% of the flux were used, and the flux contained a long-chain thiol and/or an organic chelating agent.

The special formulation of the flux is as follows:

Example 2

In this embodiment, 88.5 wt% of the alloy solder powder Sn-3.0Ag-0.5Cu, and 11.5 wt% of the flux were used, and the flux contained a long-chain thiol and/or an organic chelating agent.

The special formulation of the flux is as follows:

Example 3

In this embodiment, 88.5 wt% of the alloy solder powder Sn-3.0Ag-0.5Cu, and 11.5 wt% of the flux were used, and the flux contained a long-chain thiol and/or an organic chelating agent.

The special formulation of the flux is as follows:

Comparative example

In this example, 88.5 wt% of alloy solder powder Sn-3.0Ag-0.5Cu, and 11.5 wt% flux were used, which flux did not contain long chain mercaptans and/or organic chelating agents.

The special formulation of the flux is as follows:

Storage stability and wettability

The storage stability and weld wettability of all the examples and comparative examples were measured.

Malcom viscosity:

The viscosity before and after storage was measured using a Malcom PCU-201 viscometer. The viscosity was compared at a rotational speed of 10 rpm to show a change in viscosity.

% change in viscosity = (10 rpm viscosity after storage - 10 rpm viscosity before storage) / 10 rpm viscosity before storage

When the solder paste of the above example was stored at 30 ° C for 4 days, its storage stability was measured by Malcom viscosity. The test and comparison results are shown in Table 1.

As can be seen from the results of Table 1, the solder pastes of the present invention (Examples 1 to 3) exhibited a better storage stability than Comparative Example 1.

This means that the addition of long-chain thiols and/or o -phenanthroline can significantly improve the storage stability of the solder paste, wherein the solder wettability still performs well.

Claims (17)

A flux comprising a resin, a thixotropic agent, an activator, a solvent, and a long chain thiol and/or an organic chelating agent, wherein the long chain thiol is one or more of the formula R ( A group consisting of CH ₂ ) _n SH compounds, wherein R is a methyl group, a carboxyl group, a hydroxyl group, a decyl group or a decylamino group, and n is 7 to 21, and the organic chelating agent is an adjacent- A phenanthroline chelating agent. The flux according to claim 1, wherein the long-chain thiol is selected from the group consisting of one or more compounds having the formula R(CH ₂ ) _n SH, wherein R is a methyl group, Carboxy, hydroxy, carbenyl or decylamino, and n is from 12 to 18. The flux according to claim 1, wherein the long-chain thiol is hexyl mercaptan, octyl mercaptan, mercaptan mercaptan, dodecyl mercaptan and/or octadecyl mercaptan, and/or the like The mixture was chosen. The flux according to claim 1 or 2, wherein the organic chelating agent is selected from the group consisting of 1,10- o -phenanthroline and 2,9-dimethyl-4,7-diphenyl. 1,10-morphoporphyrin, 4,7-dimethyl-1,10- o -phenanthroline and 4,7-diphenyl-1,10- o -phenanthroline, and / Or a mixture thereof. The flux according to claim 1 or 2, wherein the long-chain thiol and/or organic chelating agent is present in an amount of from 0.2% by weight to 10% by weight based on the total amount of the flux. The flux according to claim 1 or 2, wherein the resin is selected from the group consisting of rosin resins, acid-modified rosin resins, hydrogenated rosin resins, disproportionated rosin resins and/or polymerized rosin resins, and/or a mixture of such. The flux according to claim 1 or 2, wherein the resin is present in an amount of from 10% by weight to 60% by weight based on the total amount of the flux. According to the flux described in item 1 or 2 of the patent application, wherein The agent is selected from the group consisting of polyamidamines, hydrogenated castor oils and/or guanamine-modified hydrogenated castor oils and/or mixtures thereof. The flux according to claim 1 or 2, wherein the thixotropic agent is present in an amount of from 1% by weight to 10% by weight based on the total amount of the flux. The flux according to claim 1 or 2, wherein the activator is selected from the group consisting of halogen-containing compounds, organic acids and/or organic amine compounds and/or mixtures thereof. The flux according to claim 1 or 2, wherein the activator is present in an amount of from 0.5% by weight to 30% by weight based on the total amount of the flux. The flux according to claim 1 or 2, wherein the solvent is selected from the group consisting of glycol monoethers and/or glycol diether solvents. The flux according to the first or second aspect of the invention, wherein the solvent is present in an amount of from 10% by weight to 60% by weight based on the total amount of the flux. The flux according to claim 13, wherein the solvent is diethylene glycol monohexyl ether and/or polyethylene glycol dibutyl ether. A solder paste composition in the form of a kit comprising the flux according to any one of claims 1 to 14 and at least one alloy solder powder. The solder paste composition according to claim 15, wherein the volume ratio of the flux to the alloy solder powder is from 0.8:1 to 1.2:1. A solder paste which is a mixture of all the components of the solder paste composition according to claim 15 or claim 16.