JP3694948B2 - Soldering flux, solder paste, and soldering method using them - Google Patents

Description

[0001]
[Technology to which the invention belongs]
  The present invention relates to a flux used when soldering a flip chip IC or an electronic component to a substrate and a soldering method using the same. The present invention also relates to a solder paste in which solder powder is kneaded into a paste and a soldering method using the same.
[0002]
[Prior art]
  Conventionally, a flux containing an organic acid / halide has been used in soldering a HIC (hybrid IC) and a printed circuit board. However, in recent years, chlorofluorocarbons have been promoted from the viewpoint of environmental pollution, and the use of a low-residue non-cleaning flux with a low solid content or alternative cleaning of aqueous systems is becoming mainstream. However, water-based cleaning has a problem that the cleaning performance is poor for an IC having a connection pitch structure that will be further miniaturized in the future, such as HIC. Further, even if the cleaning can be performed, if the drying is insufficient, there is a concern that leakage may occur due to moisture absorption or the like in a severe environment such as in-vehicle use. On the other hand, when there is a resin mold or wire bonding process in the subsequent process, there is a concern that the low residue flux may have an adverse effect without cleaning.
[0003]
  Moreover, in the solder paste, the material composition of the paste is 1. Solder powder, 2. Solvent, 3. It usually consists of solids (rosin, active agent, etc.). Commercially available non-cleaning-type products have been devised to reduce the solid content or not to contain halides, but after soldering, residues such as resin components such as rosin or activator components are always generated. . In particular, residues due to the activator (activator itself or reaction product) significantly degrade reliability. On the other hand, resin residues such as rosin are not a major problem when soldering printed circuit boards (for home appliances, some in-vehicle use, etc.). However, when soldering with HIC, the solder paste with such a small amount of residue, such as flip chip terminal leakage, circuit corrosion, and subsequent wire bonding reliability for products with fine connections As a result, there is a problem from the point of view, so in the end, alternative CFC cleaning and water-based cleaning are currently being implemented.
[0004]
  Therefore, recently, a non-residue type soldering method in which solder paste is reflowed using alcohol has been proposed in Japanese Patent Application Laid-Open No. 2-290693 or Japanese Patent Application Laid-Open No. 2-25291. For example, JP-A-2-90693 discloses a paste obtained by mixing alcohol (monohydric alcohol, polyhydric alcohol, ether) having a boiling point of about 30 ° C. higher than the melting point of solder with solder powder.
[0005]
[Problems to be solved by the invention]
  However, when the inventors of the present invention actually confirmed based on this document, in the non-reducing atmosphere (an atmosphere in which the reducing ability cannot be exerted with respect to the metal oxide) with ether and monohydric alcohol, solder wettability is shown at all. The solder did not spread. Also, when polyhydric alcohol examples disclosed in the examples and triethylene glycol are used, it is necessary to add a considerably large amount of alcohol (about 15 wt%), which is not suitable for use as a printing paste. It was. And even if it soldered using this, it was a level which is hard to say that soldering is favorable. Further, even when the amount of triethylene glycol was about 10 wt% to form a printing paste, the solder did not get wet (the solder did not spread), and the function as a soldering paste was not exhibited. According to the observation by the inventors of the present application with a high-temperature microscope, most of the material having a boiling point of about 30 ° C. higher than the melting point of the solder evaporates before the solder melts, which can sufficiently reduce the surface tension of the solder paste. The solder could not spread. In order to improve solder wetting in the one proposed in Japanese Patent Laid-Open No. 2-25291, soldering is performed in a reducing atmosphere. For that purpose, the temperature of the reflow furnace is set to 300 to 350 ° C. or more. Need to be hot. That is, the solder pastes proposed in these documents can be expected as a material that does not leave a residue, but cannot be expected to have good wetting in a non-reducing atmosphere or at a normal temperature.
[0006]
  Therefore, the object of the present invention is to show good wetting with respect to the base material as the bonded portion, even in a normal temperature profile and in a non-reducing atmosphere, and the residue can be substantially eliminated. It is to provide a new activator suitable for use as a binder in constituting a soldering flux or solder paste.
[0007]
[Means for Solving the Problems]
  The inventors of the present application have found that, when soldering, the component has a reducing power, and by using an organic substance present in a liquid at the start of solder melting, proper soldering can be realized. It was found that the classification of organic substances by analysis by the gravimetry method (hereinafter referred to as TG method) can be specified as a material suitable for an appropriate flux or paste. The TG method is one type of thermal analysis that can accurately detect minute changes in mass. Based on the information obtained from this analysis, the TG method is used to evaluate and classify substances used as soldering flux such as flux or paste. ing. The TG method was carried out using a commercially available SII (Seiko Denshi Kogyo Co., Ltd.) SSC-5200 measuring device. In actual measurement, a small amount of 6 to 7 mg of sample was used.
[0008]
  In order to solve the above problem, the means described in claim 1 can be employed. According to this means, it is a soldering flux, and the flux is 0% by mass when the air or nitrogen gas atmosphere flow rate is 200 ml / min and the temperature rise rate is 10 ° C./min as measured by the TG method. The temperature (hereinafter referred to as the evaporation temperature) is 170 ° C or higher and the melting point (solidus temperature) of the solder or higher and lower than the reflow peak temperature used. 2 groups per molecule and air or nitrogen (N₂) When the gas atmosphere flow rate is 200 ml / min and the temperature rise rate is 10 ° C / min, the temperature when the mass% becomes 0% is 170 ° C or higher, and the solder Including organic substances that are above the solidus temperature and below the reflow peak temperature used,The organic substance includes either an alcoholamine organic substance or a derivative thereof, or an ethanolamine organic substance or a derivative thereof,It is used for soldering in a non-reducing atmosphere. By soldering using this soldering flux, at the temperature at which the solder starts to melt, it does not decompose or evaporate but exists in a liquid state in the solder portion, and at the end of the soldering process, it decomposes or evaporates substantially. It can be made not to remain.
[0009]
  In the conventional concept of specifying flux and paste by boiling point, the present inventors found that (-OH) hydroxyl group-containing material compared to the case where a material that cannot achieve an appropriate wet state of the solder part was included. In the method of specifying the material by the TG method, a material that realizes good wetting of the solder portion and sufficient reduction of the solder surface can be surely selected. Moreover, the evaluation by the TG method shows a characteristic correlated with the vapor pressure of the substance, and an appropriate substance can be specified also by the vapor pressure. These substances act as reducing flux on solder, substrate electrode and component electrode as soldering flux or solder paste flux, decompose oxides on these surfaces, and facilitate soldering To do. In these substances, when the solder melts, the flux is present in a liquid state in the solder portion to realize a wet state, and the reduction reaction spreads the solder smoothly over the entire solder, substrate electrode, and component electrode. And form a reliable solder joint. At the time when the soldering is completed, no residue is generated due to evaporation or decomposition / evaporation of all the flux. Therefore, there is no need for post-cleaning. Moreover, the wettability and spreadability at the time of solder melting are good, and the generation of residues can be suppressed at the end of soldering.
[0010]
  In addition, the soldering flux has at least two (-OH) hydroxyl groups in one molecule, so it has sufficient reducing ability, and it is good even if soldering is performed in a non-reducing atmosphere using this soldering flux. Solder wettability can be obtained.
  The organic substance contains either a polyhydric alcohol organic substance or a saccharide or a derivative thereof, an alcohol amine organic substance or a derivative thereof, or an ethanolamine organic substance or a derivative thereof, whereby a conventional carbonyl group is obtained. Even if it does not contain a contained organic substance or a halogen compound-containing organic substance, the configuration of only the organic substance as the flux found this time has an effect as a flux as in the conventional case. In particular, a glycol organic material having at least two (—OH) hydroxyl groups, a polyhydric alcohol organic material, or a saccharide, or an alcohol amine organic material having at least two (—OH) hydroxyl groups. As a result, it is possible to make soldering easy and reliable by reducing the surface tension of the solder by strongly showing the reducing property when the solder is melted.
[0011]
  According to the means described in claim 2, soldering is performed using a soldering flux composed of a plurality of kinds of substances, which are mixed in an unreacted state. Thereby, from the difference in the vapor pressure or TG characteristic of each component, the role of the flux can be sufficiently exerted in the state where the role of the flux is shifted in terms of time or temperature at the time of melting the solder.
[0012]
[0013]
  According to the means described in claim 3, the organic substance contains an organic substance containing three (—OH) hydroxyl groups per molecule. This makes it possible to spread the solder better, especially when the organic substance contains four (-OH) hydroxyl groups in one molecule, so that the vapor pressure can be kept low. It remains without evaporating at the time of melting, and can fully exhibit its reducing ability.
[0014]
  In addition, organic substances having 3 or more (-OH) hydroxyl groups per molecule can be measured by the TG method when the flow rate of air or nitrogen atmosphere is 200 ml / min and the temperature rise rate is 10 ° C / min. Increase to 235 ° C or higher. Thereby, a solder can be spread more favorably and the quality of soldering can be improved more.
[0015]
[0016]
  Claim 41,3-dioxane-5,5-dimethanol, 1,4-dioxane-2,3-diol, 3-methyl-1,5-pentanediol, 2,5-furandamethanol , N-butyldiethanolamine, ethyldiethanolamine, diethanolamine, tetraethylene glycol, hexaethylene glycol, pentaethylene glycol, 1,2,3-hexanetriol, 1,2,6-hexanetriol, 1,2,4-butanetriol, 2,3,4-trihydroxybenzophenone, 2 ', 3', 4'-trihydroxyacetophenone, 3-methylpentane-1,3,5-triol, triethanolamine, trimethylolpropane, trimethylolethane, pyrogallol, NN-bis (2-hydroxyethyl) isopropanolamine, pentaerythritol,And a material composed of one or a combination of bis (2-hydroxymethyl) iminotris (hydroxymethyl) methane as a main component of the soldering flux.
  Claim 51,3-dioxane-5,5-dimethanol, 1,4-dioxane-2,3-diol, 1,5-pentanediol, 3-methyl-1,5-pentanediol , 2,5-furandiethanol, n-butyldiethanolamine, ethyldiethanolamine, diethanolamine, tetraethylene glycol, FXaethylene glycol, pentaethylene glycol, 1,2,3-hexanetriol, 1,2,6-hexanetriol, 1,2,4-butanetriol, 2,3,4-trihydroxybenzophenone, 2 ', 3' , 4'-trihydroxyacetophenone, 3-methylpentane-1,3,5-triol, glycerin, triethanolamine, trimethylolpropane, trimethylolethane, pyrogallol, N-N-bis (2-hydroxyethyl) isopropanolamine, pentaerythritol, AndBis (2-hydroxymethyl) iminotris (hydroxymethyl) methane is a material composed of one or a combination of two or more, and is used for soldering in a non-reducing atmosphere. .
  Thereby, by performing reflow soldering, it is possible to improve the wettability and spreadability of the solder and to prevent generation of a residue after soldering. In particular, if at least one of these materials containing 3 or more (—OH) hydroxyl groups in one molecule is mixed with solder powder and used as a paste, it exhibits good wettability and Stable quality can be maintained even in harsh environments. In addition, even when a resin is mixed to form a paste when the solder paste is prepared, no residue other than the resin is generated at the end of the soldering, and a reliable soldering can be obtained. Can do. As described above, by using a substance having at least three (—OH) hydroxyl groups in one molecule as a flux activator at the time of soldering, thixotropy can be obtained, and the component retainability can be further improved.
[0017]
  Claim 6According to the means described in (1), a distilled material among the (—OH) hydroxyl group-containing organic materials is used as the main component of the soldering flux. As a result, impurities such as high-temperature components (oxides) present in the flux are removed, the purity of the flux can be improved, the insulation resistance value can be stabilized, and high-quality soldering can be achieved. be able to. This means that the raw material which is the main component of the soldering flux may be distilled and used, and even if a commercially available material is used, the residue can be almost eliminated at the end of soldering.
[0018]
  Claim 7According to the method described in, when the air or nitrogen gas atmosphere flow rate is 200 ml / min, the temperature rise rate is 10 ° C / min, the evaporation temperature is 235 ° C or higher, and the solder solidus is measured by the TG method. A solvent having a temperature equal to or higher than the temperature and equal to or lower than the reflow peak temperature to be used is mixed with the solder powder to form a paste. This solvent contains at least three (-OH) hydroxyl groups per molecule, and air or nitrogen (N₂) When the gas atmosphere flow rate is 200 ml / min and the temperature rise rate is 10 ° C / min, the temperature when the mass% becomes 0% is 235 ° C or higher and the solder Contains organic substances that are above the solidus temperature and below the reflow peak temperature used.The organic material includes either an alcoholamine organic material or a derivative thereof, or an ethanolamine organic material or a derivative thereof.
  Thereby, the wettability at the time of solder paste melting can be made favorable.
  Solder paste may not play a role as a paste if it is highly evaporable. Therefore, it is difficult to evaporate during solder melting, that is, air or nitrogen gas flow rate 200ml / min, temperature in measurement by TG method. When the rate of increase is 10 ° C / min, the mass% at the solder melting point (180 ° C for eutectic solder) is preferably 89% or more, or the vapor pressure at the solder melting point is 20mmHg or less. Further, in the solder paste, the surface area of the solder becomes large, so that when the organic substance of the present invention as a binder is used, a larger reducing power is required. Therefore, good soldering can be realized by using a flux containing at least three (-OH) hydroxyl groups per molecule. When these materials are used as a flux, the wettability of the paste is very good. It contains at least three alcohols containing (-OH) hydroxyl group per molecule, and the evaporation temperature is 235 when the air or nitrogen gas atmosphere flow rate is 200ml / min and the temperature rise rate is 10 ℃ / min as measured by the TG method. A specific substance of ℃ or higher is mixed with solder powder as a binder and used as a paste. Thereby, the evaporability can be lowered as a flux at the time of melting the solder, and the wettability at the time of melting the solder paste can be improved.
  Also,Claim 8According to the means described in (1), the solvent comprises a solvent containing at least one of trimethylolpropane and trimethylolethane, and solder powder. Thereby, since there is no adjacent (—OH) hydroxyl group and no amine group, oxidation does not occur, and the reliability of the soldered portion can be improved.
[0019]
  Claim 9The solder paste according to claim 8 or 9 is used for soldering in a non-reducing atmosphere. Thereby, even if soldering is performed in a non-reducing atmosphere, good wettability can be obtained and almost no residue can be obtained.
[0020]
[0021]
  Claim 10According to the means, the solvent is composed of a plurality of kinds of substances, and they are mixed in an unreacted state to constitute a solvent for the solder paste. By performing soldering using a solder paste containing this solvent, the role of the solvent is sufficiently shifted in terms of time or temperature when melting the solder due to the difference in vapor pressure or TG characteristics of each component. It can be demonstrated.
[0022]
  Claim 11According to the means described in (1), an organic substance having a molecular structure in which at least three carbon atoms are interposed between all (—OH) hydroxyl groups and (—OH) hydroxyl groups is used. Thereby, since there are no adjacent (—OH) hydroxyl groups, oxidation of the organic substance hardly occurs, and the reliability of the soldered portion can be improved.
[0023]
[0024]
[0025]
  Claim 12According to the means described in the above, the solvent is measured by the TG method when the air or nitrogen gas atmosphere flow rate is 200 ml / min and the temperature rise rate is 10 ° C./min. It should be not lower than the reflow peak temperature to be used above the solidus temperature of the solder. The solvent has at least three (-OH) hydroxyl functional groups per molecule, and air or nitrogen (N₂) When the gas atmosphere flow rate is 200 ml / min and the temperature rise rate is 10 ° C / min, the temperature when the mass% becomes 0% is 235 ° C or higher and the solder Contains organic substances that are above the solidus temperature and below the reflow peak temperature used.The organic material includes either an alcoholamine organic material or a derivative thereof, or an ethanolamine organic material or a derivative thereof.The solvent and solder powder are kneaded to form a solder paste. This solder paste is supplied to the soldering part of the workpiece, and the workpiece is placed in an atmosphere capable of raising the temperature. The temperature in the atmosphere is raised to the first temperature, the first temperature is maintained for a predetermined time, and the temperature is raised to a second temperature higher than the first temperature at an average rate of 10 ° C./min or higher. By performing soldering by such a method, the solvent does not evaporate before the solder is melted, the solvent is present in the soldered portion, and the surface tension of the solder can be reduced.
  Claim 13According to the means described in 1,2,6-hexanetriol, 1,2,4-butanetriol,PentaerytritoLeSoldering is performed using at least one of them as the main component of the solvent of the solder paste. Thereby, since these materials have a large reducing power, the wettability when the solder is melted can be improved.
  Claim 14According to the means described in the above, at least one first component selected from tetraethylene glycol, hexaethylene glycol, and pentaethylene glycol, 1,2,6-hexanetriol, 3-methylpentane-1,3,5- A mixture of at least one second component among triol, glycerin, trimethylolpropane, and trimethylolethane is used as the main component of the solder paste solvent. Thereby, more preferable solder wettability is obtained.
[0026]
  Claim 15According to the means described above, soldering is performed by setting the first temperature in relation to the temperature at which the organic substance of the solvent exerts a reducing power on the metal oxide in the soldering portion. Thereby, the reduction | restoration by a solvent functions effectively and can acquire favorable wettability.
[0027]
  Claim 16According to the means described in (1), the first temperature is set to 160 ° C. or higher and the solder melting point or lower and soldering is performed. Thereby, reduction | restoration by a solvent is performed effectively, better wettability of solder can be obtained, and the reliability of a soldering part can be improved.
[0028]
  Claim 17According to the means described above, soldering is performed at a second temperature of 240 ° C. Thereby, the solvent evaporates after completion of soldering and does not remain on the substrate surface, and the reliability of the soldered portion can be further improved.
[0029]
  Claim 18According to the means described above, soldering is performed while maintaining the first temperature for 10 seconds or more and 5 minutes or less. Thereby, compared with the case where it solders without providing holding time, a reduction | restoration effect | action works more effectively and the favorable wettability of solder can be obtained. More preferably,Claim 19In other words, the soldering is performed while maintaining the first temperature for 1 to 2 minutes.
[0030]
  Claim 20According to the means, the step of distilling the organic substance of the solvent before supplying the solder paste and then kneading the solvent and the solder powder to form the solder paste is provided. Thereby, the purity of the solvent is increased, and variations in insulation resistance can be reduced.
[0031]
[0032]
[0033]
  Claim 21According to the means described in the above, the flux is air or nitrogen (N₂) Reflow used when the gas atmosphere flow rate is 200 ml / min and the temperature rise rate is 10 ° C / min, and the evaporation temperature is 170 ° C or higher and the solder solidus temperature or higher. Below peak temperature. The flux has at least two (-OH) hydroxyl functional groups per molecule, and air or nitrogen (N₂) When the gas atmosphere flow rate is 200 ml / min and the temperature rise rate is 10 ° C / min, the temperature when the mass% becomes 0% is 170 ° C or higher, and the solder Contains organic substances that are above the solidus temperature and below the reflow peak temperature used.The organic material includes either an alcoholamine organic material or a derivative thereof, or an ethanolamine organic material or a derivative thereof.This flux is attached to the soldering portion of the workpiece, the solder is supplied, and the workpiece is placed in an atmosphere capable of raising the temperature. Then, the temperature is raised at an average rate of 10 ° C./min or more at least in the temperature range above the solidus temperature of the solder. Thereby, since the flux exists without evaporating when the solder is melted, the surface tension of the solder is not lowered, and good soldering is obtained.
  Claim 22According to the means described in the above, the flux is composed of at least one of 1,5-pentanediol, 3-methyl-1,5-pentanediol, and diethylene glycol, and soldering is performed by a flow method or a dip method. As a result, at the end of soldering, some amount of these materials remains on the surface of the board, but because the board is heated, they completely evaporate in tens of seconds, regardless of the size and shape of the land portion. Good soldering can be realized.
[0034]
  Claim 23According to the means described in the above, soldering is performed while maintaining the same temperature for a predetermined period in a temperature range below the solidus temperature of the solder. Thereby, the reduction ability of the flux can be effectively exhibited.
[0035]
  Claim 24According to the means described in (1), the temperature is maintained at 160 ° C. or higher and below the melting point of the solder for 10 seconds or more and 5 minutes or less. Thereby, the flux reducing ability can be more effectively exhibited.
[0036]
  Claim 25According to the means, the soldering is performed by increasing the temperature to 240 ° C. at an average temperature increase rate of 10 ° C./min or more in a temperature range equal to or higher than the solidus temperature of the solder. Thereby, the flux does not evaporate after the soldering is completed, and the flux does not remain on the substrate surface.
[0037]
  Claim 26According to the means, the organic substance constituting the flux is distilled and then the flux is supplied together with the solder to the soldering portion of the workpiece. Thereby, impurities such as high-temperature components in the flux can be removed, and the insulation resistance value of the flux can be stabilized.
[0038]
[0039]
  Claim 27According to the means, the organic substance contained in the flux has at least three (—OH) hydroxyl groups in one molecule, and air or nitrogen (N₂) When the gas atmosphere flow rate is 200 ml / min and the temperature rise rate is 10 ° C / min, the temperature when the mass% becomes 0% is 235 ° C or higher and the solder It is higher than the solidus temperature and lower than the reflow peak temperature used, and is soldered by a flow method or a dip method. Thereby, almost no flux remains and can be soldered well regardless of the shape and size of the land portion.
[0040]
【Example】
(First Example)
  Hereinafter, the present invention will be described based on specific examples. FIG. 1 is a schematic cross-sectional view showing how the flip chip IC 1 and the chip component 2 are soldered to the substrate electrode 3 of the substrate 4 in the reflow process. The organic substance 6 (for example, 100% 1,2,6-hexanetriol) specified by the present invention was applied from the state in which the substrate 5 provided on the substrate 4 was precoated with solder 5 in advance, such as solder plating. The flip chip IC 1 and the chip component 2 are arranged in the state. In this state, the substrate 4 is passed through a reflow furnace (not shown) to melt the solder 5 and soldering is performed (FIG. 1 (a)).
[0041]
  When reflowing and soldering, hydrogen (H₂) Use gas and nitrogen gas. Or air may be sufficient. This is because in the soldering of the present invention, soldering is performed by covering the periphery of the melted solder 5 with the specified organic substance 6, so even if it is oxidized after soldering, the soldering itself This is because it has no effect. Further, as a temperature profile pattern in this reflow process, as shown in FIG. 2, a commonly used pattern of room temperature → about 235 to 250 ° C. (peak temperature) → room temperature may be used. In this embodiment, the atmosphere is an atmosphere in the furnace, but the inventors of the present application have confirmed that the same soldering is possible even in reflow on an air atmosphere and on a hot plate. In a detailed investigation of the soldered partial cross-section of the soldering formed in this way, the inventors of the present application have confirmed that a joint equivalent to soldering by flux that has been used normally has been formed. Confirmed by line element analysis.
[0042]
  As shown in FIG. 3, when the solder 21 melts, the flux used for soldering or the flux for paste is in a state where the flux 22 covers the upper surface of the solder material, so that the solder 21 quickly contacts the electrode surface. It is to let it spread out wet. If this is not the case, the solder 21 will be rounded on the electrode surface in an attempt to maintain a spherical shape with surface tension. That is, it is necessary to realize a wet state that quickly spreads as a liquid.
[0043]
  At that time, as shown in FIG. 3, the surface tension works at the end portion of the solder 21 in the liquid state on the substrate 23, and the interfacial tension between the substrate 23 and the flux 22 in the direction of the circle 1, The interfacial tension between the liquid solder 21 and the flux 22 is acting in the direction and the interfacial tension between the liquid solder 21 and the substrate 23 is acting in the direction of the circle 3, but the surface of the solder 21 where the flux 22 is melted is covered. When the flux 22 is also in a liquid state, the interfacial tension in the two round directions decreases, and the solder 21 spreads on the substrate 23. That is, the flux 22 plays a role of reducing the oxide film on the surface of the solder 21 when the solder 21 is melted and increasing the wet state of the solder 21. Therefore, when the solder 21 melts, the flux 22 needs to be spread around the solder in a liquid state.
[0044]
  Conventionally, as described above, rosin (pine pine), halides, or organic substances such as organic acids have been used as a material for realizing such a function. In view of this, the inventors of the present application have studied materials that do not generate residues, and have been able to identify a flux centered on organic materials as shown below.
[0045]
  That is, when the flux is specified, the characteristics obtained by the TG method (mass% at 180 ° C. when the flow rate of air or nitrogen gas atmosphere is 200 ml / min and the temperature rise rate is 10 ° C./min) are more than a certain amount (18% The above-mentioned materials centering on organic substances are useful as a flux, and the condition that the mass% by the TG method at 180 ° C. is 18% or more is that the vapor pressure is almost 95 mmHg. It became clear by investigation of inventors. Also, the paste needs to be a substance that does not easily evaporate, and the glycerin vapor pressure of 20 mmHg is insufficient, and needs to be less than this value.
[0046]
  Assuming the case where various organic substances are used as a flux in order to show a specific material having such characteristics, FIG. 4 shows the solder spread rate and the measurement by the TG method (condition: nitrogen gas atmosphere flow rate 200 ml / min. The relationship with the TG characteristic value (mass%) at 180 ° C. at a temperature increase rate of 10 ° C./min. In addition, the material name corresponding to the number in FIG. 4, each solder spread rate, and the mass% data in 180 degreeC by TG method are shown in FIG.
[0047]
  The solder spreading rate shown in FIG. 4 is defined by measurement as shown in FIG. That is, a solder ball having a diameter of 1 mm (residue of Sn63% Pb) 55a is placed on a thick film Cu conductor 53 together with an organic substance (solvent) 56 to be measured (FIG. 6 (a)), and a peak temperature of 235 ° C. in a nitrogen atmosphere. The result is a percentage based on the average value Z of the solder diameters that have spread as a result (FIG. 6B). As shown in FIG. 6 (c), the spread of the solder is not always uniform, so the average value Z (Z = (X + Y) / 2) of the spread is calculated and the spread ratio is ((Z− 1) / 1) × 100 (%). Since the solder ball diameter is 1 mm, a spreading rate of 100% means that the solder diameter has spread to 2 mm.
[0048]
  The percentage by the TG method indicates the characteristics of the target material, and the TG method is one of thermal analysis and is a technique for accurately measuring the evaporation characteristics of the target material by mass. The TG method is a precise balance in which a change in mass of a sample is precisely defined by a differential thermobalance, and precisely measures the mass of a substance that evaporates in units of 0.1 μg. This is different from the boiling point measurement, and since the substance evaporates more and more until reaching the boiling point, the characteristic which should be called evaporation characteristic (TG characteristic) of the substance is clarified. And what is understood from this evaporation characteristic is that classification that cannot be discriminated only by the normally known boiling point becomes possible. For example, as shown in FIG. 7, an octylene glycol (structural formula: Pr—CH (OH) CH (C) having the same boiling point (b.p) and higher than the eutectic solder melting point by 60 ° C.₂H_Five) CH₂OH, b.p = 244 ° C) and diethylene glycol (structure: HO- (CH₂)₂-O- (CH₂)₂-OH, b.p = 244 ° C) (The heating rate is 10 ° C / min and the atmospheric flow rate is 200 ml / min). In this case, both of them start to evaporate earlier than the boiling point, and all of them evaporate below the boiling point, so that the so-called boiling state does not occur.
[0049]
  The rate of mass change during evaporation decreases with a similar curve. The temperatures at which the masses reach 50% are approximately 160 ° C. and 185 ° C., respectively, as shown in FIG. Since the melting point of the solder is approximately 180 ° C., in the case of octylene glycol, the solder has already completely evaporated at the stage where the solder starts to melt, and does not function as a flux. Therefore, soldering is not possible even if it is actually used for soldering. On the other hand, diethylene glycol melts during evaporation, lowers the surface tension of the solder and flows well and becomes wet, and when soldering is completed, all the diethylene glycol will evaporate, leaving no residue. . That is, in the solder wetting start area A shown in FIG. 7, the organic material (solvent) needs to be surely present in a liquid state.
[0050]
  As described above, there are several examples in which even a polyhydric alcohol containing two (—OH) hydroxyl groups and having substantially the same boiling point is divided into a wetted material and a non-wetting material in the solder ball test. An example is shown in FIG. FIG. 8 shows that the difference in boiling point is about several degrees Celsius, while there is a difference of several tens of degrees Celsius at the evaporation temperature (mass% = 0%). Moreover, the evaporation temperature does not increase in the order of substances having the highest boiling points, and there are substances that are reversed, such as ethyldiethanolamine and 1,5-pentanediol. As can be seen from the comparison of these materials, by examining the evaporation temperature by the TG method, it can be determined whether or not the solder ball is wet depending on whether the evaporation temperature is higher or lower than the melting point of the solder. I can say that.
[0051]
  Another reason why the evaporation temperature cannot be predicted from the boiling point will be described. FIG. 9 describes the characteristics of a material whose evaporation temperature is almost the same as 190 ° C. The boiling points of these materials range from 243 ° C. to 276 ° C. and 40 ° C. or more, indicating that the evaporation temperature cannot be predicted from the boiling point. FIG. 9 shows that even when the evaporation temperature is higher than the melting point of the solder, the wettability may not be exhibited depending on the number of (—OH) hydroxyl groups. That is, it can be seen that the suitability to the flux cannot be determined simply based on the boiling point value.
[0052]
  From the above viewpoints, the inventors of the present application have found that the boiling point is not a standard for specifying the material, and the TG characteristic is a standard. Since this TG characteristic is related to evaporation, it also corresponds to the vapor pressure. Since the vapor pressure depends on the temperature, the reference temperature should be a temperature at which the solder melts. As described above, when using a substance centered on an organic substance as a flux, it is preferable not to judge the suitability from the boiling point, but to judge and classify the data based on the data obtained from the TG method. It becomes possible only by classification by the result.
[0053]
  Accordingly, based on the TG characteristics as shown in FIG. 7, as shown in FIG. 4, the residual amount (mass%) of each substance at 180 ° C. and the substance used in the soldering flux are shown in FIG. As a result of comparison with the defined solder spread ratio, it has been shown that many organic substances are useful as paste fluxes. In addition, among the points indicating the individual organic substances shown in FIG. 4, those having only one (—OH) hydroxyl group had a solder spreading rate of 0% and could not be soldered. FIG. 9 described above shows the material characteristics at an evaporation temperature of approximately 190 ° C. (above the eutectic solder melting point). From this figure, the number of (—OH) hydroxyl groups can also be compared. According to this, it can be seen that all those having two (—OH) hydroxyl groups are wet, but one having one or zero (—OH) hydroxyl groups does not show any wetting. That is, an organic material having weak or no reducibility to the solder surface and the substrate (substrate electrode surface) has no effect as a flux. And in the case of two (-OH) hydroxyl groups, it was confirmed that solder spreads and soldering can be carried out when the TG characteristic is 18% or more.
[0054]
  In the case of organic substances having three (-OH) hydroxyl groups (mainly polyhydric alcohols), the solder spread ratio exceeds 70% and the TG characteristics substantially exceed 80%. In the case of an organic substance (mainly sugars) having four (-OH) hydroxyl groups, the vapor pressure is low and it can be used as a solder paste. Since this is difficult to evaporate, it is easy to realize as a paste.
[0055]
  Thus, the characteristic regarding the temperature of the organic material made into object is acquired. That is, as shown in the characteristics shown in FIG. 4, a material classification different from the classification based on the boiling point (bp) can be performed, so that a more accurate classification for applying as a flux can be performed, and many materials can be applied. I was able to make it clear.
[0056]
  The spread rate of the solder is also related to the temperature at which the mass% by the TG method becomes 0%. FIG. 10 shows the relationship between the solder spread rate and the temperature (evaporation temperature) at which the mass% becomes 0% as measured by the TG method (conditions of nitrogen gas atmosphere flow rate 200 ml / min, temperature rise rate 10 ° C./min). From FIG. 10, it is understood that in order for the solder to spread out, a substance having two or more (—OH) hydroxyl groups in one molecule and having an evaporation temperature higher than 185 ° C. may be selected. The details of the material names corresponding to the numbers in FIG. 10, the respective solder spread ratios, the mass% data at 180 ° C. and the temperature data at mass% = 0% by the TG method are shown in FIG. It is.
[0057]
  In addition, among the materials shown in FIGS. 5 and 10, as a representative, 1,2,6-hexanetriol (number 24 in the figure), tetraethylene glycol (number 18 in the figure), trimethylolpropane (number in the figure) No. 33), trimethylolethane (No. 32 in the figure), and glycerin (No. 30 in the figure) change in mass% by the TG method are shown in FIG. 11, FIG. 12, FIG. 13, FIG. In each figure, the characteristic line TG indicates mass% by the TG method, and the characteristic line DTG indicates the rate of change of the characteristic line TG. For reference, a characteristic line DTA representing an endothermic amount is also shown in each figure. As shown in FIGS. 11 to 15, TG% decreases as the temperature rises, eventually reaches 0%, and is completely evaporated. Data on each material was collected using the temperature at this time as the evaporation temperature, and FIG. 5 was obtained based on the data. FIG. 10 was obtained based on FIG. The inventors of the present application have acquired a lot of data in addition to the data shown in FIG. 5, and a list of these data is shown in FIG.
[0058]
  FIG. 17 and FIG. 18 show the organic substances that have been confirmed to have a high solder spread ratio and good soldering, including the organic substances shown in FIG. FIG. 17 is a list of substances that can obtain the characteristics of the present invention with a single substance when distilled, and FIG. 18 shows the characteristics of the present invention with a single substance even when not distilled. This is a list of substances that can be used. In addition, among the items in FIGS. 17 and 18, “Presence / absence of residue in TG” indicates whether or not the TG characteristic is 0%. “Vapor pressure at 180 ° C.” indicates literature values, and those not in literature are parenthesized estimates.
[0059]
  Among the commercially available organic substances shown in FIG. 17, a trace amount of residue remains in the TG characteristic, such as 1,2,4-butanetriol and 3-methylpentane-1,3,5-triol. However, when it is used after distillation, almost no residue is observed, confirming that there is no problem. Further, among the organic substances shown here, those that do not react with each other may be mixed and used. This is because when each organic substance works as a flux, the role of the flux may be sufficiently exerted in the state of time or temperature deviation when the solder is melted due to the difference in vapor pressure or TG characteristics. It is.
[0060]
  In addition, even organic substances not shown in FIGS. 17 and 18 have many materials having the characteristics of the present invention, and any of them can be used as flux or paste flux. Therefore, it is possible to provide many soldering mounting methods that are free of residue and do not require post-cleaning. In particular, the fact that it is effective as a flux or paste flux even if it does not contain any organic substances conventionally used, such as carbonyl group-containing organic substances and halogen compound-containing organic substances, means that the application range is greatly expanded. FIG. 19 shows organic substances that did not fall under the present invention. In FIG. 4, the material has a solder spreading rate of 0% (bottom horizontal axis). The present inventors have confirmed that these cannot be soldered.
[0061]
  By the way, the conditions for classifying the organic materials that can be used as the flux, that is, the conditions of the TG method are conditions for specifying the target substance as the flux, and are not necessarily the conditions to be implemented in the actual process. In the actual process, there are various methods such as how to raise the temperature of the reflow furnace and changing the temperature rise characteristics in the middle. Therefore, the specified organic substance may be used in accordance with the actual use conditions. The conditions measured by the TG method this time are almost the same as the following environment (in a 4-zone nitrogen reflow furnace, reflow is performed at a temperature profile of about 90 ° C / min and 160-170 ° C for about 1 min). The present inventors have confirmed that this is an environment by observing the amount of evaporation of the material.
[0062]
  In the above description, eutectic solder (Sn: about 63% Pb balance) having a melting point of about 180 ° C. is used as the solder. However, a solder composition having a solidus temperature of about 180 ° C. (for example, Sn is about The inventors of the present application have confirmed that soldering can be performed under the same conditions even if it is 18-97.5% Pb balance). The above solder is Sn-Pb type (including additives such as Ag, In, Cu, Bi, Sb), but other solders such as Bi type and In type low temperature solders have a melting point of 130 ° C. Attempts to perform solder ball tests using solder at 139 ° C and 165 ° C. These materials showed no reducing power at their respective melting points and began to wet at about 170 ° C. This is also clear from the fact that the oxide film cannot be removed unless the representative examples of these materials are 165 to 170 ° C. or higher (see FIG. 27 described later). Therefore, the soldering flux conditions are as follows: mass% by TG method at a melting point of 170 ° C. or higher is 18% or more, and (—OH) hydroxyl groups are two or more in one molecule and are liquefied during soldering, TG It is sufficient that the temperature (evaporation temperature) at which the mass% by the method becomes 0% is 170 ° C. or more, the solder melting point or more, and two (—OH) hydroxyl groups in one molecule.
[0063]
  Further, it has been confirmed that soldering can be performed as in the first embodiment, even when using about 10 g of erythritol dissolved in about 5 g of tetraethylene glycol with the remainder of Sn10% Pb, which is a high-temperature solder. The substrate electrode is an electrode made of at least one of solder, Sn, Cu, Ag, Ni, Au, Pt, Pd, or an alloy thereof, or a thick film conductor, and is usually used. Most materials can be applied.
[0064]
  (Second embodiment)
  As the solder supply method, solder plating is used in the first embodiment, but the effect of soldering is the same even when the solder pellet (solder foil) 7 is formed and applied together with the specified flux 6. The inventors of the present application have confirmed (see FIG. 1B). As one specific example, tetraethylene glycol (100%) is preliminarily applied as a solvent 6 to a land (substrate electrode) 3 on which the chip component 2 is mounted using a dispenser. Next, a foil-like solder (pellet) 7 having a size substantially equal to that of the land 3 is placed on the solvent 6, and the chip component 2 is mounted thereon. With respect to the flip chip IC1, since the solder bumps 5 are formed in advance on the flip chip IC1, it is not necessary to place a solder foil. The substrate 4 mounted in this manner is passed through a reflow furnace and soldered.
[0065]
  In addition, although said application | coating method is implemented with dispenser, printing may be sufficient. Further, the inventors of the present application have confirmed that even if only the land 3 is applied or the entire substrate 4 is applied, it evaporates completely after reflow. Regarding the order of application, a step of applying a flux after placing the solder foil may be taken. The reflow environment may be Air or an inert atmosphere, and may be soldered in a furnace or reflowed on a hot plate. In this example, tetraethylene glycol was described as an example of the flux. However, even if other materials as shown in FIGS. 17 and 18 shown in the first example are used as the flux, The present inventors have confirmed that the present invention can be applied to soldering.
[0066]
  (Third embodiment)
  Next, the case where the solder paste 8 is used will be described (see FIG. 1C). The solder paste 8 is a solder powder mixed with a solvent as a paste, and is used by applying a cream-like solder paste to the soldering area. Since the solder powder increases the surface area of the solder, it requires a greater reducing power when the solder is melted. Therefore, when the organic material of the present invention is used as a solvent for the solder paste 8, it is necessary that there are three (—OH) hydroxyl groups. In addition, at this time, it is necessary to have liquidity. In the case of paste, in order to obtain a semi-kneaded state, it is necessary to contain a solvent at about 10 wt% with respect to the solder. That is, as compared with each of the above embodiments, the amount of the solvent that acts as a flux is small, and the same temperature profile may evaporate quickly. Therefore, even if it has a large reducing power, it does not make sense if the solvent is not present at the time of soldering, and therefore a paste having a low vapor pressure is suitable as a paste. In fact, glycerin alone having a mass% by the TG method of about 82% and a vapor pressure of about 20 mmHg at 180 ° C. was not effective as a paste.
[0067]
  The following are the pastes with good results. For example, about 9 wt% (9 g) of 1,2,6-hexanetriol, which is a polyhydric alcohol, is used as an example of a solvent in about 100 g of solder powder of 25 to 40 μm Sn62% Ag2% Pb balance (JISH62Ag2). Knead. Since this solvent has a high viscosity of 2584 cps at room temperature, a paste that can be printed with a metal mask and a mesh mask can be obtained without adjusting the viscosity. The solder paste is printed on the substrate 4 using a metal mask and a mesh mask, and then the chip component 2 and the flip chip IC 1 are mounted, and in that state, the solder paste is passed through a reflow furnace and soldered.
[0068]
  (Fourth embodiment)
  As a specific example of another solder paste, about 12.3 g of trimethylolpropane (also known as 1,1,1-trispropane or 1,1,1-hydroxymethylpropane), which is solid at room temperature, is sufficiently ground using a mortar. When dissolved in about 6.2 g of tetraethylene glycol used as a solvent and stirred well, it becomes a gel. This is put into 138.9 g of the remaining solder powder of 25 to 40 μm of Sn62% Ag2% Pb and kneaded sufficiently. Using this as a solder paste, soldering is performed in a reflow furnace through a printing process as in the third embodiment. In this example, two specific organic substances are mixed to share a reducing property and a liquid property (wetting property) to make it easy to use.
[0069]
  As the solder paste, the following are examples of combinations in which more preferable solder wetting has been confirmed by experiments. 1. 1,2,6-hexatriol simple substance. 2. Triethanolamine alone. 3. A mixed system of tetraethylene glycol and trimethylolpropane. 4). Mixed system of diethanolamines, tetraethylene glycol and 1,2,6-hexatriol glycerin. 5. The mixed system with the other solvent shown in FIG.17 and FIG.18 which added the triethanolamine more than trace amount (0.045% or more to 100%). 6. Mixed system of 1,2,6-hexatriol and trimethylolpropane. 7). A mixed system of trimethylolpropane, water and tetraethylene glycol. These 1. ~ 7. Both are about 8-12wt% of the solder powder and become a paste state with a viscosity comparable to that of commercially available solder pastes (however, samples that are solids depend on solubility, but other than solder) Is about 8 to 14 wt% of the ingredients).
[0070]
  In the examples of the paste shown in the third and fourth examples, it was also found that the generation of solder balls is suppressed in addition to the effect that no residue is generated. This is because the composition material of this proposal does not contain any resin, so the solder balls left far away due to the rise in temperature rise are absorbed without trouble when melting the solder and do not remain after soldering as solder balls. is there. This has been found by comparing the present plan with a commercially available paste under a high-temperature microscope.
[0071]
  (Fifth embodiment)
  The group of the inventors of the present application has already shown a method for manufacturing a protruding electrode using a flux in Japanese Patent Application Laid-Open No. 64-5039. In this case as well, the organic substance specified by the present invention can be applied. For example, as shown in the schematic structural cross-sectional view of FIG. 20, land portions 82 are formed at 200 μm pitch in the same arrangement as the electrodes 83 of the flip chip IC 84 by solder plating on the transfer substrate 81 side. . On the IC 84 side, a flip-chip IC 84 is used in which titanium (Ti) / copper (Cu) is continuously deposited on the Al wiring electrode as a barrier electrode after forming a passivation film, and then a copper (Cu) electrode 83 is formed by plating. The flip chip IC 84 is adsorbed by a dedicated chip mounter 85, and, for example, tetraethylene glycol as a solvent is transferred by a tray having a thickness of about 30 μm, and then positioned in a jig by a recognition device and transferred to the transfer substrate 81 Move to move. While the IC chip 84 side is heated to about 240 ° C., the transfer is performed by lowering the solder on the transfer substrate 81 side. The solder electrode 83 thus transferred allows the solvent to evaporate, and can be transferred without washing and without residue.
[0072]
  (Sixth embodiment)
  The case where it applies to the vehicle-mounted HIC board | substrate based on each said Example is shown. An example is shown in which a flip chip IC and a chip component are mounted on a ceramic substrate for HIC formed of a copper (Cu) conductor and having a distance between electrodes of a minimum width of 100 μm. For example, the flux or paste of the above-described embodiment is applied or printed on the electrode part. A chip component and a flip chip IC are mounted on this with a dedicated mounter. Then, reflow is performed using a nitrogen furnace. Reflow uses a temperature profile pattern that is held at about 160 ° C. for 1 minute and has a peak temperature of about 235 ° C. The heating rate is about 60 ° C./min.
[0073]
  After being soldered in this way, wire bonding mounting is performed. At this time, it is known that even without cleaning, the bonding strength is comparable to that of a conventional cleaned product, and the tensile strength is ensured. In addition, the inventors of the present application have confirmed that the product made in this way has no leaks and the like, and exhibits the same characteristics in terms of quality as a conventional cleaning product. Further, the inventors of the present invention have confirmed that there is no residue in the vicinity of the soldered portion visually, and that there is no peak that appears to be an organic substance in microscopic FT-IR (Fourier Transformation-Infrared) analysis (ie, there is no flux component). are doing.
[0074]
  (Seventh embodiment)
  The flux components shown so far have a configuration that does not contain an organic acid / halogen compound. An example is shown in which a small amount of an organic acid is added to the flux component at about 240 ° C. so that the mass% by the TG method is 0%. The organic acid reacts with the metal oxide to form a salt, so it does not become completely residue-free. However, if the mass% by the TG method is 0%, the organic acid itself is evaporated or thermally decomposed, so a trace amount of residue It can be soldered with. Therefore, an organic acid or the like that is thermally decomposed and evaporated is added to the flux material configured in the embodiments described so far.
[0075]
  For example, the above-described flux constituent materials shown in FIGS. 17 and 18 are capric acid (CH_Three-(CH₂)₈-COOH: aka decanoic acid) is added to the flux by soldering in the same reflow process. It has been found that the flux added in this way further improves the wettability, and shows a particularly good wettability especially in the case of a paste.
[0076]
  As described above, the substance that can be added to the flux of the present invention without inferior to the present invention must be such that at least the mass% before and after the peak temperature is 0% as measured by the TG method. The present inventors have confirmed that with carboxylic acids such as lactic acid and oleic acid, the mass% by the TG method does not become 0%, and several tens of μg to several mg remain as a residue and cannot be used. In addition to the carboxylic acid shown above, the inventors of the present application confirmed that a material such as adipic acid whose mass% by the TG method is 0% at around 240 ° C. is also effective.
[0077]
  (Eighth Example)
  The above description is all explained in the reflow soldering process, but the flow process is the same as the soldering process, and the effect of the flux is the same. FIG. 21 shows how the circuit components 31 to 33 are soldered to the substrate wiring 35 of the substrate 34 in the flow process. As the flow process, for example, soldering by jet soldering is shown. After temporarily mounting circuit components 31 to 33 such as shrink-type ICs and chip components fixed to the back surface of the substrate 34 on the substrate 34 (see FIG. 21A), the flux is applied from the back surface of the printed circuit board 34. (Here, for example, glycerin among the materials shown in FIGS. 17 and 18) is applied over the entire surface. The substrate 34 is subjected to a preheating step of heating at about 150 ° C., passing through a jet solder bath, brought into contact with the molten solder at about 240 ° C., and dried with a fan. In this way, the flux of the circuit board 31 to 33a of the circuit components 31 to 33a and the substrate wiring 35 are electrically connected to each other by the solder 36 by the flow soldering. There is almost no residue, and plays the same role (reduction action, improvement of wetting) as shown in the reflow process.
[0078]
  (Ninth Example)
  For example, about 8 g of rosin and about 15 g of 1,2,6-hexanetriol are mixed as resin components with about 200 g of the remaining solder powder of 25 to 40 μm of Sn62% Ag2% Pb, and sufficiently kneaded to form a paste. Using this paste, printing is performed on a printed circuit board in the same manner as in the third embodiment. In the product soldered in this way, only a resin component remains as a residue, but other components are evaporated and decomposed, and soldering with good reliability becomes possible. That is, by adopting the material of the present plan in place of the activator and solvent of the commercial paste, it is possible to perform soldering that surpasses the commercial low residue flux in terms of reliability. Also, in terms of solderability, good results were obtained compared to the case where no resin was used. In this example, rosin was used as the resin, but similar results were obtained even when an acrylic resin was used in addition to rosin. Further, 1,2,6-hexanetriol was used as a component other than the resin, but a mixture of tetraethylene glycol and a solvent capable of dissolving rosin such as butyl carbitol or α-terpineol may be substituted.
[0079]
  (Tenth embodiment)
  For example, about 12.5 g of trimethylolpropane sufficiently ground in a mortar is dissolved in about 15.3 g of tetraethylene glycol while slightly adding temperature. Trimethylolpropane does not completely dissolve, but can be applied sufficiently as it is. Using this solvent, a Sn 60% Pb remaining solder is applied on a substrate supplied in advance, and a chip component and a flip chip IC having 400 μm pitch Sn 40% Pb remaining bumps are mounted thereon. Then, reflow is performed using a belt reflow furnace in an inert atmosphere. SEM (Scanning Electron Microscopy) observation and FT-IR show that in a normal profile (see Fig. 2) with a peak temperature of about 240 ° C, all the solvent evaporates after soldering and does not remain as a residue at all. The inventors have confirmed by analysis.
[0080]
  Tetraethylene glycol, which is a divalent alcohol, is not very viscous at room temperature. However, when trimethylolpropane is added as a solid at room temperature, the viscosity increases, and thixotropic properties are obtained. Will be better. Thus, it was found that polyhydric alcohols that are solid at room temperature are also effective as thixotropic agents. Polyhydric alcohols that are solid at room temperature include trimethylolethane and 1,2,3-hexanetriol in addition to the above materials, and these materials were also found to be effective as thixotropic agents. The mixing ratio of the solvent and the solid is about 1: 1 in this embodiment, but similar joining is possible even if the amount of trimethylolpropane is increased. Further, as shown in the second embodiment, tetraethylene glycol alone is also effective, but mixing with trimethylolpropane has a stronger reducing power and can be soldered more reliably.
[0081]
  (Eleventh Example)
  Dissolve about 12.6 g of trimethylolethane, which has been thoroughly crushed in a mortar, in about 9.7 g of tetraethylene glycol. This trimethylolethane does not completely dissolve, but becomes a milky white gel-like liquid. To this, 25 to 40 μm of Sn60% Pb remaining eutectic solder powder is mixed using a spatula (metal spatula for stirring), and then sufficiently mixed using a kneader. As the kneading machine, a self-revolving type manufactured by Japan Unix Co., Ltd. was used, and kneading was performed for about 30 minutes. The product made in this way becomes a paste and is at a printable level. This paste is used to print on a ceramic substrate for measuring insulation resistance. This substrate has a counter electrode formed of a Cu thick film at a pitch of 100, 200, and 300 μm, and can measure an insulation resistance after reflow. The reflow was performed using a belt reflow furnace in a nitrogen atmosphere. Trimethylolethane has a melting point of 200 ° C. However, according to the TG method, sublimation started to be remarkable from about 150 ° C before 200 ° C, showed a reducing power before the solder melted, and showed good wettability. . After that, PCBT (Pressure Cooker Bias Test) was performed. The conditions were about 120 hours under severe test conditions of a temperature of 121 ° C., a humidity of 85%, and a voltage applied to the counter electrode of 24V.
[0082]
  In addition to the above materials, a similar test was conducted using a mixed paste in which 1,2,6-hexanetriol, triethanolamine and trimethylolpropane were mixed with tetraethylene glycol. Also, as a soldering method other than paste, PCBT is also used for samples that have been pre-frozen after the solder is supplied to the substrate electrode side by dipping or the like and then thoroughly washed and coated with the same material such as 1,2,6-hexanetriol. Went. The results are shown in FIG. 22 for the paste and FIG. 23 for the flux. In such a severe test, what is almost the same as the initial state is a flux other than trimethylolpropane paste, trimethylolethane paste and paste soldering, and these materials and soldering methods are particularly severe such as in-vehicle. It can be said that it is suitable when used in an environment. In particular, in the paste, a decrease in insulation resistance was observed for materials other than trimethylolpropane and trimethylolethane. This is due to the material structure. That is, first, the material does not contain an amine group, secondly, it does not contain (OH) hydroxyl groups that are close to each other in the molecule, and a material that satisfies these two conditions can provide more reliable soldering. Will provide.
[0083]
  FIG. 24 shows the structural formula of 1,2,6-hexanetriol, the structural formula of trimethylolpropane, and the structural formula of trimethylolethane, respectively. 1,2,6-hexanetriol has a close (-OH) hydroxyl group (see FIG. 24 (a)), but trimethylolpropane or trimethylolethane has no close (-OH) hydroxyl group. , (—OH) At least three carbon atoms are present between hydroxyl groups (see FIGS. 24B and 24C). If there are (-OH) hydroxyl groups close to each other in the structure, the oxidation of the solvent itself is more likely to proceed, and the alcohol group becomes a carbonyl group at the oxidized site, forming a Sn salt, etc., reducing reliability. It becomes a factor. This can be easily imagined from the fragment ions of the spectrum by MS (Mass Spectrometry). That is, while there is a relatively strong carbonyl or aldehyde fragment peak presumed to be due to the close (-OH) hydroxyl group from the spectrum peak by MS of 1,2,6-hexanetriol, trimethylol It is not found strongly in propane or trimethylolethane. In other words, 1,2,6-hexanetriol is more likely to oxidize within the molecule, and a trace amount of metal salt is produced in pastes that have many opportunities to come into contact with Sn oxides (Sn ions) like pastes. Therefore, a decrease was observed in a strict reliability test.
[0084]
  On the other hand, triethanolamine is a material having a structure similar to trimethylolpropane. This material has very good wettability due to the presence of amine groups, but it works in the direction that oxidation tends to occur like 1,2,6-hexanetriol. The result was similar to that of 6-hexanetriol.
[0085]
  (Twelfth embodiment)
  Add about 24.6g of trimethylolpropane to about 9.7g of tetraethylene glycol to about 200g of solder powder of Sn62% Ag2% Pb remainder of 25-40μm, then mix with a spatula, and then use a revolving kneader Knead. Using this paste, it is printed and coated in the same manner as in the third embodiment, and then reflowed in a nitrogen atmosphere furnace. The reflow profile at this time is shown in FIG. As shown in FIG. 25, the profile was maintained at around 165 ° C. for 1 minute, and the other temperature raising speed was about 90 ° C./minute. Thus, by providing a time for holding at about 170 ° C., better solderability could be obtained. The temperature to be held can be determined based on the temperature (see FIG. 27) at which trimethylolpropane starts to show reducing power with respect to the electrode material.
[0086]
  FIG. 26 shows a flow of a method for measuring an oxide film removing ability. A material is applied to a Cu oxide or Sn oxide substrate and then reflowed using XPS (X-ray Photoelectron Spectroscopy). The method of measuring the oxide film thickness is shown. FIG. 27 shows the measurement results when trimethylolpropane and trimethylolethane were applied on an oxidized Cu substrate using the method shown in FIG. According to FIG. 27, in the case of trimethylolpropane, the reduction reaction starts from about 160 ° C. and can be completely removed at 175 ° C. For this reason, holding the temperature at about 170 ° C. is effective. The inventors of the present application have also investigated the same reducing ability in the trimethylolethane paste, and found that the wettability is exhibited even when maintained at about 165 ° C. On the other hand, in the trimethylolpropane paste, the wettability as high as about 170 ° C retention profile was not obtained with the about 165 ° C retention profile. Thus, it has been found that the profile for holding the material applied on the metal oxide in the reduction region is an important process for ensuring wettability, and the holding temperature differs for each material.
[0087]
  Further, as shown in FIG. 28, the inventors of the present application have investigated not only the oxide film thickness removing ability of the Cu substrate but also the oxide film thickness removing ability of various materials for Sn. In this embodiment, reflow is performed with the temperature profile shown in FIG. 25. However, soldering is possible even if no holding time is provided. As for the holding time, good effect was exhibited by holding for about 10 seconds, and better wettability was shown compared to the case of not holding. The holding time is about 10 seconds to 5 minutes, more preferably about 1 to 2 minutes. Regarding the rate of temperature increase, since the data on the change in mass% by the TG method is data measured at 10 ° C./min, it is desirable that at least the average of the actual rate of temperature increase is 10 ° C./min or more. In particular, it is desirable to raise the temperature at an average of 10 ° C./min or more from the temperature at which evaporation begins. For example, in the case of eutectic solder, since the TG characteristic data (FIGS. 11 to 15) of each material starts to evaporate remarkably from about 170 ° C., when the temperature profile of the reflow is raised from the holding temperature, the temperature rise If the speed is low, the solvent evaporates before the solder is melted, and the effect of lowering the surface tension of the solder cannot be expected when the solder is melted. Therefore, it is necessary to define the rate of temperature rise at least above the temperature at which evaporation of the solvent becomes intense. On the contrary, at a temperature lower than that, there is almost no evaporation of the solvent material, so that it is not necessary to define the rate of temperature rise.
[0088]
  As a measure for measuring the reducing ability, in addition to the number of (—OH) hydroxyl groups in one molecule, the proportion of (—OH) hydroxyl groups in the molecule can be considered. FIG. 29 shows the relationship between (—OH) hydroxyl group / molecular weight × 100 (%) and the amount of oxide film thickness that can be removed. FIG. 29 shows that there is a reducing ability (about 1 to 2 nm) capable of removing a natural oxide film from a material having a value of (—OH) hydroxyl group / molecular weight × 100 exceeding about 17.5%. It was also found that the reducing ability increased as the proportion of (-OH) hydroxyl group in the molecule increased. From this figure, it can be seen that the reduction capacity required for the paste (3 or more (-OH) hydroxyl groups) is approximately 38% or more in terms of (-OH) hydroxyl group / molecular weight × 100.
[0089]
  (Thirteenth embodiment)
  A commercially available 1,2,6-hexanetriol is distilled under reduced pressure of a rotary pump. Although distillation can be performed at about 180 to 190 ° C. under a pressure of about 5 mmHg, since the purpose is to remove only impurities such as high-temperature components (oxides), it is effective even if precision distillation is not used. 1,2,6-hexanetriol is slightly yellow in the commercial product, but is colorless and transparent after distillation. This material is coated with 300,150,75,50μm pitch Cu thick film facing each other, and the above distilled 1,2,6-hexanetriol and undistilled 1,2,6 on the evaluation substrate that can measure the insulation resistance. -After applying hexanetriol, it was reflowed in a nitrogen atmosphere furnace. FIG. 30 shows the result of comparing the initial insulation resistance depending on the presence or absence of the distillation treatment of each material. From FIG. 30, it can be seen that the insulation resistance value of the non-distilled material has a remarkable variation and the insulation resistance is also a low value. On the other hand, it was found that an alcohol having a high boiling point such as ethanol has a level that can be used without distillation even if it is commercially available with a normal purity.
[0090]
  Tetraethylene glycol and glycerin were also distilled as materials other than 1,2,6-hexanetriol, and the insulation resistance was measured. On the other hand, since trimethylolpropane and trimethylolethane were solid at room temperature, an attempt was made to improve the purity by a recrystallization method, but the effect was not obtained so much. Thus, it was found that the same effects as other materials can be obtained by forced distillation in the same manner as a room temperature liquid material. Forcible distillation was performed by using a distiller (glass apparatus) that normally distills liquid under reduced pressure, removing the Liebig tube (cooling part), and scraping off the material adhering to the inside of the glass. In the case of trimethylol ethane, it sublimates before the melting point, and it has been found that the same effect can be obtained by using a material collected by sublimation. In addition, since trimethylolpropane has a melting point of 58 ° C., it can be easily collected as a liquid if it is distilled while heating the instrument with a dryer or the like.
[0091]
  (14th embodiment)
For example, as shown in FIG. 31, 1,2,4-butanetriol distilled as the specific organic substance 18 is thinly applied with a cotton swab or the like on a wiring pattern formed of Cu conductors 13 at a pitch of 250 μm. A flip chip IC 11 (224 bumps formed) in which solder bumps 15 are formed at a pitch of 250 μm on this wiring is mounted using a high-precision mounter. The electrode 15 of the flip chip IC 11 is formed by forming the remaining Sn71% Pb solder on the Cu bump. After mounting, it was reflowed at a peak temperature of about 240 ° C. in a nitrogen atmosphere furnace. As a result, it was found that there is no solder on the Cu conductor 13 side, and soldering can be performed well even at a fine pitch of 250 μm. By increasing the reflow peak temperature by about 10-20 ° C and using 1,2,6-hexanetriol or pentaethylene glycol as the coating material, in addition to the above IC electrode materials, the composition of about 100% Sn or AgSn eutectic solder Good soldering can be performed.
[0092]
  A highly viscous polyhydric alcohol material such as 1,2,6-hexanetriol has poor wettability with respect to the substrate, and for a huge chip of about 15 to 20 mm such as a driver IC, Depending on the method of application, there may be a case where a bonding failure occurs. Therefore, good soldering is possible by soldering using the following method. 1,2,6-hexanetriol is used as a solvent with poor wettability with respect to the substrate, tetraethylene glycol is used as a solvent with good wettability with respect to the substrate, and a mixed solution is prepared with each compounding ratio being 10: 1 (mass ratio). . Since this mixed solution has a lower surface tension with respect to the substrate than 1,2,6-hexanetriol, it can be applied thinly and uniformly to the substrate. After that, a flip chip IC is mounted on a mounter, and reflow is performed in nitrogen. The inventors of the present application have confirmed that these mixed solutions are also effective as a dip flux.
[0093]
  Examples of solvents that have poor wettability with respect to the substrate include 1,2,4-butanetriol, 3-methylpentane-1,3,5-triol, glycerin, and the like. Examples include 5-pentanediol, tetraethylene glycol, triethylene glycol, diethylene glycol, and 3-methyl-1,5-pentanediol. When these solvents are mixed at a desired blending ratio, the wettability with respect to the substrate is improved, the solvent can be applied thinly and uniformly, and as a result, the solderability can be improved.
[0094]
(15th Example)
  In a ceramic substrate having a wiring formed of an Ag or Cu-based thick film, for example, 1,2,6-hexanetriol of the materials shown in FIGS. 17 and 18 is applied onto at least the wiring as a flux material. As shown in FIG. 32, this substrate 44 is vertically immersed in a solder bath 47 containing molten solder 45 made of the composition of the remaining Sn62% Ag2% Pb and held at about 235 ° C. After being immersed for about 2 seconds, when pulled up at an angle of about 45 degrees with respect to the liquid level, a slight amount of material remains on the surface of the substrate 44. In this state, the substrate 44 is again immersed vertically in the solder bath 47 for about 3 seconds, and is slowly pulled up at an angle of about 45 degrees with respect to the liquid level. The substrate 44 dipped in this manner can be soldered satisfactorily regardless of the shape and size of the land portion with little flux material remaining depending on the amount of material applied. Even if it remains, the amount is very small and not carbonized, so it can be removed with ethanol or the like, or it is evaporated after the subsequent component mounting reflow, and finally does not remain as a residue. By using this substrate 44 to mount components by the method shown in the first embodiment, no cleaning is possible in all the steps.
[0095]
  In the present embodiment, a thick film is used as the substrate wiring material. However, the inventors of the present application have confirmed that it is possible to use a plated metal that can be soldered to the substrate wiring material. . In the above description, the material is applied to the substrate 44 side. However, soldering can be performed in the same manner by supplying the material directly to the upper surface of the solder bath 47 and dipping the substrate 44 there. The present inventors have confirmed.
[0096]
(16th Example)
  100% 1,5-pentanediol (with 2 (-OH) hydroxyl groups, evaporation temperature (mass% = 0% temperature)) is 190.8 for ceramic substrate with wiring made of Ag or Cu thick film D) perpendicular to the liquid surface. After soaking for about 5 seconds, pull up vertically from the liquid. Then, the substrate is kept vertical for about 30 seconds, and this substrate is slowly vertically immersed in a solder bath maintained at about 235 ° C. composed of the composition of the remaining Sn62% Ag2% Pb. When held in the solder bath for about 2 seconds and then pulled up vertically, a small amount of 1,5-pentanediol remains on the surface of the substrate, but the substrate is heated. Pentanediol will completely evaporate.
[0097]
  The substrate thus dipped can be satisfactorily soldered regardless of the size and shape of the land portion without leaving any solvent on the surface. In the dip using propylene glycol (evaporation temperature = about 150 ° C.) whose evaporation temperature by the TG method is lower than 190 ° C., the solvent has already evaporated when it is pulled up after immersion, and a large amount of solder residue adheres to the substrate. On the other hand, with glycerin (evaporation temperature = 230 ° C.) whose evaporation temperature by the TG method is higher than 190 ° C., good soldering is possible, but a solvent that could not be evaporated in one dip remains. Therefore, in a solder bath maintained at about 235 ° C, a material having two or more (-OH) hydroxyl groups and an evaporation temperature of about 190 ° C can be soldered with one dipping, and It can be said that it is a material that can be completely evaporated.
[0098]
  Even a material having an evaporation temperature of 190 ° C. or higher can be subjected to non-cleaning dip soldering in the same manner as the above material by adding a drying step after dipping. By using the substrate thus dipped and mounting the components by the method shown in the first embodiment, no cleaning is possible in all steps. The inventors of the present application obtained similar results to 1,5-pentanediol even with 3-methyl-1,5-pentanediol, diethylene glycol, etc. as materials having TG characteristics equivalent to 1,5-pentanediol. It is confirmed that In this embodiment, the ceramic substrate is used as the substrate, but the inventors of the present application have confirmed that the same dip is possible even with a printed circuit board.
[0099]
(17th Example)
  Next, an example in which wettability is exhibited by mixing solvents that do not exhibit wettability alone will be described below. For example, a mixed system of n-dodecanol and octylene glycol. These materials are materials that do not exhibit wettability alone. In other words, n-dodecanol has only one (-OH) hydroxyl group, so it has poor reducing power, but the temperature at which the mass% becomes 0% is 190 ° C, so it has the effect of reducing the surface tension when the solder is melted. To do. On the other hand, octylene glycol has a function of reducing the surface tension when solder is melted because the temperature at which the mass% becomes 0% is 180 ° C. However, it has two (-OH) hydroxyl groups, so it has a reducing power. Is enough. Thus, it is good also considering the mixed system of the material which supplements the fault of both as a flux. Actually, a material in which about 10 g of n-dodecanol and about 20 g of octylene glycol were sufficiently mixed was prepared, and when the component was mounted by using the mixed material by the method shown in the first embodiment, it was surely soldered. I was able to. As a material, soldering was possible even by substituting alkane (n-hexadecane) containing no (—OH) hydroxyl group in place of the above-mentioned n-dodecanol.
[0100]
  As indicated above, according to the present invention, among soldering fluxes containing at least two (—OH) hydroxyl groups per molecule, 170 ° C. or higher under predetermined conditions as measured by the TG method. By using a soldering flux containing at least one substance whose mass% in the solder melting point is 18% or more, solder wettability and spreadability can be improved, and soldering without residue can be performed. In addition, among soldering fluxes containing at least two (—OH) hydroxyl groups in one molecule, the temperature at which the mass% becomes 0% under a predetermined condition as measured by the TG method is the melting point of the solder (solid phase Also, by using a soldering flux containing at least one kind of substance having a temperature of (linear temperature) or higher and 170 ° C. or higher, solder wettability and spreadability are good, and soldering without residue can be performed. It is also effective to perform soldering by the dipping method using this soldering flux.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a state of soldering by reflow.
FIG. 2 is a schematic diagram showing a temperature profile during reflow.
FIG. 3 is an explanatory view showing a state of solder wetting.
FIG. 4 is a relational diagram showing the relationship between the solder wetting spread rate of organic substances and the mass% by the TG method at 180 ° C.
FIG. 5 is a correspondence diagram showing correspondence between numbers in FIG. 4 and materials.
FIG. 6 is an explanatory diagram showing the definition of the solder spread ratio.
FIG. 7 is a characteristic diagram of thermal gravimetry in octylene glycol and diethylene glycol.
FIG. 8 is an explanatory diagram showing the relationship between the evaporation temperature and wettability of a material having the same boiling point among materials having two (—OH) hydroxyl groups.
FIG. 9 is an explanatory diagram showing characteristics such as an evaporation temperature, the number of (—OH) hydroxyl groups, and a solder spreading ratio in a material having substantially the same boiling point.
FIG. 10 is a relationship diagram showing the relationship between the solder wetting spread rate of the organic substance and the temperature (evaporation temperature) when the mass% by the TG method is 0%.
FIG. 11 is a characteristic diagram of thermal gravimetry in 1,2,6-hexanetriol.
FIG. 12 is a characteristic diagram of thermal gravimetry in tetraethylene glycol.
FIG. 13 is a characteristic diagram of thermal gravimetry in trimethylolpropane.
FIG. 14 is a characteristic diagram of thermal gravimetry in trimethylolethane.
FIG. 15 is a characteristic diagram of thermal gravimetry in glycerin.
FIG. 16 is an explanatory diagram showing the relationship between the solder wetting spread rate of an organic substance and the temperature (evaporation temperature) when the mass% by TG method and the mass% by TG method at 180 ° C. are 0%.
FIG. 17 is a list of substances having the characteristics of the present invention as a single substance (when distilled).
FIG. 18 is a list of substances having the characteristics of the present invention as a single substance (when not distilled).
FIG. 19 is a list showing examples of substances that do not have the characteristics of the present invention as a single substance.
FIG. 20 is a schematic sectional view showing the structure of a fifth embodiment.
FIG. 21 is a schematic sectional view showing a state of soldering by a flow.
FIG. 22 is a graph showing a PCBBT test result of a paste.
FIG. 23 is a graph showing the results of a flux PCBT test.
FIG. 24 is a structural diagram showing the structure of 1,2,6-hexanetriol, the structure of trimethylolpropane, and the structure of trimethylolethane.
FIG. 25 is a schematic diagram showing a temperature profile during reflow.
FIG. 26 is an explanatory view showing a method for measuring the Cu oxide film removal ability.
FIG. 27 is a relational diagram showing the relationship between the thickness of Cu oxide film from which trimethylolpropane and trimethylolethane have been removed and the temperature.
FIG. 28 is a relationship diagram showing the relationship between the Sn oxide film thickness that was removed when the Sn plated substrate was held at 180 ° C. for 1 minute and the material.
FIG. 29 is a relationship diagram showing the relationship between the proportion of (—OH) hydroxyl groups in the molecular weight and the thickness of Sn oxide film that can be removed.
FIG. 30 is a characteristic diagram showing initial insulation resistance depending on whether or not each material is distilled.
FIG. 31 is a schematic sectional view showing mounting of a fine flip chip in a fourteenth embodiment.
FIG. 32 is a schematic diagram showing a solder dipping method.
[Explanation of symbols]
1 Flip chip IC (FC-IC)
2 Chip parts
3 Substrate electrode
4 Substrate
5 Solder (IC side doubles as FC electrode)
6 Specified organic substances (flux)
7 Solder pellets
8 Solder paste containing specific organic substances
11 Flip chip IC
13 Cu conductor
14 Ceramic substrate
15 Solder bump
18 Specific organic matter
21 Solder
22 Flux (specified organic substances)
23 Substrate
31-33 Circuit parts
34 Substrate
35 Substrate wiring
36 Solder
44 substrates
45 Solder
47 Solder bath
53 Thick film Cu conductor
55a Solder ball
56 Solvent
81 Transfer substrate
82 Land part
83 electrodes
84 Flip chip IC (FC-IC)
85 Dedicated chip mounter with pulse heater and suction head

Claims (27)

A soldering flux,
The flux is the temperature at which the mass% becomes 0% as measured by the thermal gravimetry method when the air or nitrogen (N ₂ ) gas atmosphere flow rate is 200 ml / min and the temperature rise rate is 10 ° C./min. Is above the reflow peak temperature to be used because it is 170 ° C or higher and the solder solidus temperature or higher,
As its components, there are at least two (-OH) hydroxyl functional groups per molecule, and the thermal when the air or nitrogen (N ₂ ) gas atmosphere flow rate is 200 ml / min and the temperature rise rate is 10 ° C / min. Including the organic substance whose temperature when the mass% becomes 0% is 170 ° C. or higher and higher than the solidus temperature of the solder and lower than the reflow peak temperature used, as measured by the gravimetry method,
The organic material includes either an alcoholamine organic material or a derivative thereof, or an ethanolamine organic material or a derivative thereof,
A soldering flux characterized by being used for soldering in a non-reducing atmosphere. 2. The soldering flux according to claim 1, wherein the soldering flux is made of a plurality of types of substances and they are mixed in an unreacted state. The organic substance has three or more (-OH) hydroxyl functional groups per molecule, thermal gravitation when air or nitrogen (N ₂ ) gas atmosphere flow rate is 200 ml / min and temperature rise rate is 10 ° C / min. 3. The soldering flux according to claim 1, wherein the temperature at which the mass% becomes 0% as measured by a metric method is 235 ° C. or more and the reflow peak temperature to be used or less. A soldering flux,
1,3-dioxane-5,5-dimethanol, 1,4-dioxane-2,3-diol, 3-methyl-1,5-pentanediol, 2,5-furandumethanol, n-butyldiethanolamine, ethyldiethanolamine , Diethanolamine, tetraethylene glycol, hexaethylene glycol, pentaethylene glycol, 1,2,3-hexanetriol, 1,2,6-hexanetriol, 1,2,4-butanetriol, 2,3,4-trihydroxy Benzophenone, 2 ', 3', 4'-trihydroxyacetophenone, 3-methylpentane-1,3,5-triol, triethanolamine, trimethylolpropane, trimethylolethane, pyrogallol, NN-bis (2-hydroxyethyl ) isopropanolamine, pentaerythritol,及 beauty bis (2-hydroxymethyl) iminotris (hydroxymethyl) one or a plurality of methane Flux for soldering, characterized in that it consists of a combination of. A soldering flux,
1,3-dioxane-5,5-dimethanol, 1,4-dioxane-2,3-diol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2,5-furandamethanol, n- butyl diethanolamine, ethyl diethanolamine, diethanolamine, tetraethylene glycol, f hexa ethylene glycol, pentaethylene glycol, 1,2,3-hexanetriol, 1,2,6-hexanetriol, 1,2,4-butanetriol, 2,3,4-trihydroxybenzophenone, 2 ', 3', 4'-trihydroxyacetophenone, 3-methylpentane-1,3,5-triol, glycerin, triethanolamine, trimethylolpropane, trimethylolethane, pyrogallol, N-N-bis (2-hydroxyethyl) isopropanolamine, pentaerythritol,及 beauty bis (2-hydroxymethyl) iminotris (hydroxymethyl Consists of one or more combinations of methyl) methane,
A soldering flux characterized by being used for soldering in a non-reducing atmosphere. The soldering flux according to claim 1 , wherein the organic substance is a distilled product. Solder powder,
The temperature when the mass% is 0% when the air or nitrogen (N ₂ ) gas atmosphere flow rate is 200 ml / min and the temperature rise rate is 10 ° C / min. And consisting of a solvent that is above the solidus temperature of the solder and below the reflow peak temperature used,
When the solvent component has at least three (-OH) hydroxyl functional groups per molecule, the air or nitrogen (N ₂ ) gas atmosphere flow rate is 200 ml / min, and the temperature rise rate is 10 ° C / min. Measured by thermal gravimetry method, contains organic substances whose mass% is 0% at a temperature of 235 ° C or higher and higher than the solidus temperature of solder and lower than the reflow peak temperature used. ,
Solder paste characterized in that the organic substance includes an alcoholamine organic substance or a derivative thereof, or an ethanolamine organic substance or a derivative thereof . Solder powder,
When the flow rate is 200 ml / min and the temperature rise rate is 10 ° C / min when the air or nitrogen (N ₂ ) gas atmosphere flow rate is 10 ° C / min , the temperature when the mass% becomes 0 % is 235 ° C or more And consisting of a solvent that is above the solidus temperature of the solder and below the reflow peak temperature used,
9. The solder paste according to claim 8, comprising at least one of trimethylolpropane and trimethylolethane as a component of the solvent. The solder paste according to claim 7 or 8 , wherein the solder paste is used for soldering in a non-reducing atmosphere. The solder paste according to claim 7 , wherein the solvent is composed of a plurality of kinds of substances and they are mixed in an unreacted state. The solder paste according to claim 7 , wherein the organic substance has a molecular structure in which at least three carbon atoms are interposed between all (-OH) hydroxyl groups and (-OH) hydroxyl groups. Solder powder,
The temperature when the mass% is 0% when the air or nitrogen (N ₂ ) gas atmosphere flow rate is 200 ml / min and the temperature rise rate is 10 ° C / min. And preparing a solder paste composed of a solvent that is higher than the solidus temperature of the solder and lower than the reflow peak temperature to be used,
The solvent has at least three (-OH) hydroxyl functional groups per molecule, thermal gravitation when air or nitrogen (N ₂ ) gas atmosphere flow rate is 200 ml / min and temperature rise rate is 10 ° C / min. Including the organic substance whose temperature when the mass% becomes 0% is not less than 235 ° C. and above the solidus temperature of the solder and not more than the reflow peak temperature used, as measured by the measurement method,
The organic material includes either an alcoholamine organic material or a derivative thereof, or an ethanolamine organic material or a derivative thereof,
The paste is supplied to the soldering part of the workpiece, the workpiece is placed in an atmosphere capable of raising the temperature, the temperature is raised to a first temperature, the first temperature is maintained for a predetermined time, and the first temperature is increased. A soldering method, wherein the temperature is increased to a second temperature higher than the temperature at an average temperature increase rate of 10 ° C / min or more. Solder powder,
1,2,6-hexanetriol, 1,2,4-butanetriol, and based on at least one of Bae Ntaeritorito Le, air or nitrogen (N ₂₎ gas atmosphere flow rate 200 ml / min, temperature rise rate Reflow peak temperature when the temperature when the mass% is 0 % when measured at 10 ° C / min is 235 ° C or higher and above the solidus temperature of the solder. Prepare a solder paste consisting of the following solvent,
The paste is supplied to the soldering part of the workpiece, the workpiece is placed in an atmosphere capable of raising the temperature, the temperature is raised to a first temperature, the first temperature is maintained for a predetermined time, and the first temperature is increased. A soldering method, wherein the temperature is increased to a second temperature higher than the temperature at an average temperature increase rate of 10 ° C./min or more. Solder powder,
A first component of at least one of tetraethylene glycol, hexaethylene glycol, and pentaethylene glycol; 1,2,3, hexanetriol, 3-methylpentane-1,3,5-triol, glycerin, trimethylolpropane, Thermal gravimetry with a mixture of at least one second component of trimethylolethane as the main component , air or nitrogen (N ₂ ) gas atmosphere flow rate of 200 ml / min , and temperature rise rate of 10 ° C / min. Prepare a solder paste consisting of a solvent whose temperature when its mass% reaches 0 % is 235 ° C or higher and higher than the solidus temperature of the solder and lower than the reflow peak temperature used. And
The paste is supplied to the soldering part of the workpiece, the workpiece is placed in an atmosphere capable of raising the temperature, the temperature is raised to a first temperature, the first temperature is maintained for a predetermined time, and the first temperature is increased. A soldering method, wherein the temperature is increased to a second temperature higher than the temperature at an average temperature increase rate of 10 ° C./min or more. 15. The first temperature according to claim 12 , wherein the first temperature is set in relation to a temperature at which the organic substance of the solvent exerts a reducing power on the metal oxide of the soldered portion. The soldering method in any one. The soldering method according to any one of claims 12 to 14 , wherein the first temperature is a temperature not lower than 160 ° C and not higher than a melting point of the solder. The soldering method according to claim 12 , wherein the second temperature is 240 ° C. The soldering method according to claim 12 , wherein the predetermined time for maintaining the first temperature is 10 seconds to 5 minutes. The soldering method according to claim 12 , wherein the predetermined time for maintaining the first temperature is 1 to 2 minutes. Before the step of supplying the solder paste, the method includes the step of kneading the solder powder and the solvent to prepare the solder paste, and the step includes a step of distilling the organic substance of the solvent before kneading. The soldering method according to claim 12 , wherein the soldering method is performed. When the flow rate of air or nitrogen (N ₂ ) gas is 200 ml / min and the rate of temperature rise is 10 ° C / min, the temperature when the mass% is 0% is 170 ° C or higher. And a flux that is above the solidus temperature of the solder and below the reflow peak temperature to be used,
This flux has at least two (-OH) hydroxyl functional groups per molecule, thermal gravitation when air or nitrogen (N ₂ ) gas atmosphere flow rate is 200 ml / min, and temperature rise rate is 10 ° C / min. Including the organic substance whose temperature when the mass% becomes 0% is 170 ° C. or higher and higher than the solidus temperature of the solder and lower than the reflow peak temperature used, as measured by the measurement method,
The organic material includes either an alcoholamine organic material or a derivative thereof, or an ethanolamine organic material or a derivative thereof,
The flux is attached to the soldered part of the workpiece, the solder is supplied, and the workpiece is placed in an atmosphere capable of raising the temperature, and at least in the temperature range equal to or higher than the solidus temperature of the solder, an average of 10 ° C./min A soldering method, wherein the temperature is increased at the above temperature increase rate. A flux consisting of at least one of 1,5-pentanediol, 3-methyl-1,5-pentanediol and diethylene glycol is attached to the soldered part of the workpiece,
Solder is supplied by flow method or dip method,
A method for soldering, wherein the work is placed in an atmosphere capable of raising a temperature, and the temperature is raised at an average rate of 10 ° C./min or higher at least in a temperature range equal to or higher than a solidus temperature of the solder. The soldering method according to claim 21 or 22 , wherein the step of raising the temperature includes a step of maintaining the same temperature for a predetermined period in a temperature range equal to or lower than a solidus temperature of the solder. 24. The soldering method according to claim 23 , wherein the temperature to be held is a temperature not lower than 160 ° C. and not higher than the melting point of the solder, and the predetermined period for holding is not shorter than 10 seconds and not longer than 5 minutes. The soldering method according to any one of claims 21 to 24 , wherein in the temperature raising step, the temperature is raised to 240 ° C. The soldering method according to any one of claims 21 to 25 , further comprising a step of distilling the organic substance before the step of supplying the flux. The organic substance contained in the flux has at least three (—OH) hydroxyl functional groups per molecule, an air or nitrogen (N ₂ ) gas atmosphere flow rate of 200 ml / min, and a temperature increase rate of 10 ° C. / When measured by the thermal gravimetry method when min, the temperature when the mass% becomes 0% is 235 ° C or more, and is above the solidus temperature of the solder and below the reflow peak temperature used. ,
The soldering method according to claim 21 , wherein the solder is supplied by a flow method or a dip method.

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