DE112021002818T5 - ELECTRICALLY CONDUCTIVE COMPOSITION, ELECTRICALLY CONDUCTIVE SINTERED PART AND ELECTRICALLY CONDUCTIVE SINTERED PART COMPONENT - Google Patents

Abstract

The present invention relates to an electrically conductive composition, a component with a sintered or joined part in which the electrically conductive composition is used, preferably an electronic component, and more preferably an electronic component for mounting in vehicles or for communication devices, electrically conductive A composition containing electroconductive fillers and resin particles, wherein the rate of change in the maximum Feret diameter of the resin particles before and after sintering the electroconductive composition is less than 1.20. The electroconductive composition may contain (A) silver microparticles with an average particle diameter of 10 to 300 nm, and (B) metal particles with an average particle diameter of 0.5 to 10 μm as the electroconductive fillers, and (C) resin particles with an average Contain particle diameters of 2 to 15 microns.

Description

[Technical Field]

The present invention relates to an electrically conductive composition, an electrically conductive sintered part, a component with a sintered or joined part in which the electrically conductive composition is used, a method for joining components and a method for producing an electrically conductive sintered part, in particular an electrically conductive composition applied to electronic components, e.g. B. electronic parts for mounting in vehicles or used for communication equipment, and electronic parts having a sintered part obtained by sintering the electrically conductive composition.

[State of the art]

In the field of electronics, electrically conductive compositions are used, e.g. B. organic resins and electrically conductive fillers such as metal microparticles as adhesives for the formation of adherends in electronic components, z. B. semiconductor components or as electrically conductive pastes for forming circuits on printed circuit boards. After being applied to a component, such electrically conductive compositions are sintered or thermoset to form a sintered or bonded part.

As for the metal microparticles used as electroconductive fillers, it is known from Patent Document 1 that by using micron-sized particles and nanometer-sized particles in combination, electric conductivity and thermal conductivity in the electroconductive composition after sintering are improved.

In Patent Documents 2 and 3, it is stated that by using plate-shaped silver microparticles having a central particle diameter of 0.3 to 15 µm and a thickness of 10 to 200 nm in an electroconductive thermosetting resin composition, a composition excellent in thermal conductivity, low stress, adhesive properties and reflow peel strength can be obtained.

In Patent Document 4, an electroconductive composition for sintering is disclosed, which contains: (A) silver microparticles with a number-average particle diameter of the primary particles of 40 nm to 400 nm, (B) a solvent, and (C) thermoplastic resin particles with a maximum value of the endothermic peak in a DSC chart obtained by measurement using a differential scanning calorimeter is in the range of 80°C to 170°C, where the number average particle diameter of the primary particles of the thermoplastic resin particles is 1 to 50 µm. It is stated that in this electrically conductive composition, the thermoplastic resin particles in the electrically conductive composition melt and deform when the electrically conductive composition is sintered, so that the generation of voids is avoided, which is due to the shrinkage of the electrically conductive composition when the composition is cured can occur, and cracks in the bonded component, cracks in the part to be joined and detachment of the joint interfaces can be avoided.

In Patent Document 5, there is disclosed an electroconductive composition containing electroconductive fillers (B) having an average particle diameter of 0.5 to 10 μm and thermoplastic resin particles (A) which are in a solid state at 25°C. In addition, Patent Document 6 discloses an electroconductive adhesive composition containing: electroconductive fillers (A) with metal particles (a1) having an average particle diameter of 0.5 to 10 µm and silver particles (a2) having an average particle diameter of 10 to 200 nm , and thermoplastic resin particles (B) which are in a solid state at 25°C. It is stated that in the electroconductive adhesive composition disclosed in Patent Document 6, thermal conductivity is improved by the combined use of micron-sized metal particles and nanometer-sized silver particles. In these patent documents, it is stated that by the electrically conductive adhesive composition containing thermoplastic resin particles which are in the solid state at 25°C, the thermoplastic resin particles melt during sintering or thermosetting and the adhesive at the adhesive interface between the cured electrically conductive adhesive and the The bonded material fills the gaps between the bonded materials, thereby improving the bond strength and stress relaxation, and avoiding the occurrence of peeling due to temperature fluctuations. Also, in Patent Document 7, there is disclosed an electroconductive adhesive composition containing micrometer-sized metal particles and nanometer-sized silver particles size as electrically conductive fillers and contains thermoplastic resin particles with an average particle diameter of 2 to 14 µm and a melting point of 130 to 250 °C. Here, too, it is stated that the thermoplastic resin particles melt by heating and fill the intermediate gaps in the cured electrically conductive adhesive, as a result of which detachment of the bonded material can be prevented.

[Detected Fonts]

[patent documents]

• [Patent Document 1] Patent Publication No. JP 2015-162392
• [Patent Document 2] Patent Publication No. JP 2016-65146
• [Patent Document 3] Patent Publication No. JP 2014-194013
• [Patent Document 4] International Publication No. WO 2016/063931
• [Patent Document 5] International Publication No. WO 2019/013230
• [Patent Document 6] International Publication No. WO 2019/013231
• [Patent Document 7] International Publication No. WO 2020/145170

[Overview of the invention]

[Object to be solved by the invention]

In the case of electrically conductive compositions in the prior art, electrically conductive fillers are used which contain silver particles which can be sintered at low temperatures, so that a sintered part or joined part obtained after sintering the electrically conductive composition shows excellent joint strength and good electrical conductivity. On the other hand, in a sintered or bonded member using nanometer-sized silver particles, voids tend to occur inside the bonded member because the shrinkage caused by the sintering of the nanometer-sized silver particles becomes larger. Furthermore, since the distortion between the sintered part and the bonded part increases, the use of nanometer-sized silver particles is detrimental to the long-term reliability of the bonded part in which dissimilar materials such as a silicon chip and a lead frame or substrate are bonded. On the other hand, it is known that by using thermoplastic resin particles having a maximum value of the specific endothermic peak, the thermoplastic resin melts and deforms when sintering the electrically conductive composition, and fills the gaps in the sintered part, thereby avoiding the formation of voids in the joined part, the detachment of the joining part can be avoided and the joint strength can be improved (see 1 and 2 ). However, even if such electrically conductive compositions are used, there is still the problem that relatively large electronic components, e.g. B. with chips from about 5 × 5 mm to 8 × 8 mm in size easily detaches when cold / heat cycles are repeated.

In particular, in the case of electronic components for mounting in vehicles, the operating temperature varies greatly in the range of up to -50°C to 150°C, so that an electrically conductive composition is desired which, even under such severe conditions, has a highly reliable joining part for electronic components large area is obtained.

Accordingly, the present invention has for its object an electrically conductive composition with which a sintered part or joined part is obtained, which has high electrical conductivity and thermal conductivity, and, even if the component has a large area, for a by the repetition of Cold / heat cycles caused detachment of the component from an object to be joined after sintering the electrically conductive composition is less susceptible, and to provide a method for joining the component using the electrically conductive composition or a method for producing an electrically conductive sintered part or joined part.

[solution of the task]

The inventors have found that in a sintered body matrix of the electroconductive composition containing nanometer-sized silver microparticles and micrometer-sized metal particles as contains electrically conductive fillers, the micron-sized particles composed of resin, etc., surprisingly are not significantly deformed due to melting by heating and are uniformly distributed in the sintered part in the state in which the shape before sintering is substantially maintained, whereby these resin particles do not can only reduce the stress but also disperse it, and thus it is possible to achieve both high electric conductivity and long-term joining reliability in the joining part of the dissimilar materials joined using the electrically conductive composition, especially in the joining part for joining chips with a relatively large area, leading to the completion of the present invention.

• [1] Elektrisch leitfähige Zusammensetzung, die elektrisch leitfähige Füllstoffe und Harzpartikel enthält, wobei die Änderungsrate des maximalen Feret-Durchmessers der Harzpartikel vor und nach dem Sintern der elektrisch leitfähigen Zusammensetzung weniger als 1,20 beträgt.
• [2] Elektrisch leitfähige Zusammensetzung nach Abschnitt [1], wobei die Änderungsrate des maximalen Feret-Durchmessers im Bereich von 0,9 bis 1,1 liegt.
• [3] Elektrisch leitfähige Zusammensetzung nach Abschnitt [1] oder [2], wobei die Temperatur, bei der die elektrisch leitfähige Zusammensetzung gesintert wird, im Bereich von 80°C bis 300°C liegt.
• [4] Elektrisch leitfähige Zusammensetzung nach einem der Abschnitte [1] bis [3], die (A) Silbermikropartikel mit einem mittleren Partikeldurchmesser von 10 bis 300 nm als die elektrisch leitfähigen Füllstoffe enthält.
• [5] Elektrisch leitfähige Zusammensetzung nach Abschnitt [4], die (B) Metallpartikel mit einem mittleren Partikeldurchmesser von 0,5 bis 10 µm als die elektrisch leitfähigen Füllstoffe enthält.
• [6] Elektrisch leitfähige Zusammensetzung nach Abschnitt [5], die als die Harzpartikel (C) Harzpartikel mit einem mittleren Partikeldurchmesser von 2 bis 15 µm enthält.
• [7] Elektrisch leitfähige Zusammensetzung nach Abschnitt [6], wobei das Harz, aus dem die Harzpartikel (C) bestehen, aus der Gruppe eines thermoplastischen Harzes, eines wärmehärtenden Harzes und eines Silikonharzes ausgewählt wird.
• [8] Elektrisch leitfähige Zusammensetzung nach Abschnitt [7], wobei das thermoplastische Harz aus der Gruppe von Polyolefinen und Polyamiden ausgewählt wird.
• [9] Elektrisch leitfähige Zusammensetzung nach einem der Abschnitte [6] bis [8], wobei der mittlere Partikeldurchmesser der Harzpartikel (C) 1 bis 85% der Dicke eines Sinterteils bzw. Fügeteils entspricht, der nach dem Sintern der elektrisch leitfähigen Zusammensetzung erhalten wird.
• [10] Elektrisch leitfähige Zusammensetzung nach einem der Abschnitte [6] bis [9], wobei die elektrisch leitfähige Zusammensetzung die Silbermikropartikel (A) zu 5 bis 50 Masse-%, die Metallpartikel (B) zu 35 bis 85 Masse-% und die Harzpartikel (C) zu 0,1 bis 10 Masse-% bezogen auf die Masse der elektrisch leitfähigen Zusammensetzung enthält.
• [11] Elektrisch leitfähige Zusammensetzung nach einem der Abschnitte [1] bis [10], wobei die elektrisch leitfähige Zusammensetzung ferner (D) ein Bindemittelharz zu 0,5 bis 10 Masse-% bezogen auf die Masse der elektrisch leitfähigen Zusammensetzung enthält.
• [12] Elektrisch leitfähige Zusammensetzung nach einem der Abschnitte [5] bis [11], wobei das Verhältnis der Silbermikropartikel (A) zu den Metallpartikeln (B) in der elektrisch leitfähigen Zusammensetzung im Bereich von 5:95 bis 60:40 im Massenverhältnis liegt.
• [13] Elektrisch leitfähige Zusammensetzung nach einem der Abschnitte [1] bis [12], die ferner mindestens eine Komponente enthält, die aus der Gruppe bestehend aus einem Härtungsmittel, einem Härtungsbeschleuniger, einem Lösungsmittel, einem Antioxidationsmittel, einem UV-Absorber, einem Klebrigmacher, einem Viskositätseinsteller, einem Dispergiersmittel, einem Haftvermittler, einem Zähigkeitsvermittler und einem Elastomer ausgewählt wird.
• [14] Verfahren zum Fügen von Bauteilen unter Verwendung einer elektrisch leitfähigen Zusammensetzung nach einem der Abschnitte [1] bis [13], umfassend einen Schritt zum Sintern der elektrisch leitfähigen Zusammensetzung, so dass die Änderungsrate des maximalen Feret-Durchmessers der Harzpartikel nach dem Sintern bezogen auf den maximalen Feret-Durchmesser der Harzpartikel vor dem Sintern weniger als 1,20 beträgt.
• [15] Verfahren zur Herstellung eines elektrisch leitfähigen Sinterteils bzw. eines elektrisch leitfähigen Fügeteils unter Verwendung einer elektrisch leitfähigen Zusammensetzung nach einem der Abschnitte [1] bis [13], umfassend einen Schritt zum Sintern der elektrisch leitfähigen Zusammensetzung, so dass die Änderungsrate des maximalen Feret-Durchmessers der Harzpartikel nach dem Sintern bezogen auf den maximalen Feret-Durchmesser der Harzpartikel vor dem Sintern weniger als 1,20 beträgt.
• [16] Verfahren nach Abschnitt [14] oder [15], wobei die Temperatur, bei der die elektrisch leitfähige Zusammensetzung gesintert wird, im Bereich von 80°C bis 300°C liegt.
• [17] Verfahren nach einem der Abschnitte [14] bis [16], wobei die Aufheizgeschwindigkeit beim Sintern der elektrisch leitfähigen Zusammensetzung 1 bis 10°C/min beträgt.
• [18] Verwendung der elektrisch leitfähigen Zusammensetzung nach einem der Abschnitte [1] bis [13] zur Bildung eines Fügeteils von Bauteilen, einer elektrisch leitfähigen Schicht oder einer Schaltung.
• [19] Sinterteil bzw. Fügeteil, der elektrisch leitfähige Füllstoffe und Harzpartikel enthält, wobei das Sinterteil bzw. das Fügeteil durch Sintern der elektrisch leitfähigen Zusammensetzung nach einem der Abschnitte [1] bis [13] erhalten wird, wobei bezogen auf die Schnittfläche des Sinterteils bzw. Fügeteils der Anteil der elektrisch leitfähigen Füllstoffe 60 bis 95 Flächen-% beträgt, der Anteil der Harzpartikel 1 bis 35 Flächen-% beträgt, der Anteil der Komponenten verschieden von den Harzpartikeln und den elektrisch leitfähigen Füllstoffen und den Zwischenspalten 4 bis 25 Flächen-% beträgt, und der mittlere Partikeldurchmesser der Harzpartikel 2 bis 15 µm beträgt.
• [20] Bauteil mit einem Sinterteil bzw. Fügeteil nach Abschnitt [19].

The embodiments of the present invention are as follows:

• [1] An electroconductive composition containing electroconductive fillers and resin particles, wherein the rate of change of the maximum Feret diameter of the resin particles before and after sintering the electroconductive composition is less than 1.20.
• [2] The electrically conductive composition according to item [1], wherein the rate of change of the maximum Feret diameter is in the range of 0.9 to 1.1.
• [3] The electrically conductive composition according to item [1] or [2], wherein the temperature at which the electrically conductive composition is sintered is in the range of 80°C to 300°C.
• [4] The electroconductive composition according to any one of [1] to [3], which contains (A) silver microparticles having an average particle diameter of 10 to 300 nm as the electroconductive fillers.
• [5] The electroconductive composition according to item [4], which contains (B) metal particles having an average particle diameter of 0.5 to 10 µm as the electroconductive fillers.
• [6] The electrically conductive composition according to item [5], which contains, as the resin particles (C), resin particles having an average particle diameter of 2 to 15 µm.
• [7] The electrically conductive composition according to item [6], wherein the resin constituting the resin particles (C) is selected from the group consisting of a thermoplastic resin, a thermosetting resin and a silicone resin.
• [8] The electrically conductive composition according to item [7], wherein the thermoplastic resin is selected from the group consisting of polyolefins and polyamides.
• [9] The electroconductive composition according to any one of [6] to [8], wherein the average particle diameter of the resin particles (C) corresponds to 1 to 85% of the thickness of a sintered compact obtained after sintering the electroconductive composition .
• [10] The electrically conductive composition according to any one of paragraphs [6] to [9], wherein the electrically conductive composition, the silver microparticles (A) to 5 to 50% by mass, the metal particles (B) to 35 to 85% by mass and the Resin particles (C) at 0.1 to 10% by mass based on the mass of the electrically conductive composition.
• [11] The electroconductive composition according to any one of [1] to [10], wherein the electroconductive composition further contains (D) a binder resin at 0.5 to 10% by mass based on the mass of the electroconductive composition.
• [12] The electroconductive composition according to any one of [5] to [11], wherein the ratio of the silver microparticles (A) to the metal particles (B) in the electroconductive composition is in the range of 5:95 to 60:40 by mass .
• [13] The electroconductive composition according to any one of [1] to [12], further containing at least one component selected from the group consisting of a curing agent, a curing accelerator, a solvent, an antioxidant, an ultraviolet absorber, a tackifier , a viscosity adjuster, a dispersant, a coupling agent, a toughener and an elastomer.
• [14] A component joining method using an electroconductive composition according to any one of [1] to [13], comprising a step of sintering the electroconductive composition so that the rate of change of the maximum Feret diameter of the resin particles after sintering based on the maximum Feret diameter of the resin particles before sintering is less than 1.20.
• [15] A method for producing an electrically conductive sintered part or an electrically conductive joining part using an electrically conductive composition according to any one of paragraphs [1] to [13], comprising a step of sintering the electrically conductive composition so that the rate of change of the maximum Feret diameter of the resin particles after sintering relative to the maximum Feret diameter of the resin particles before sintering is less than 1.20.
• [16] The method according to item [14] or [15], wherein the temperature at which the electroconductive composition is sintered is in the range of 80°C to 300°C.
• [17] The method according to any one of [14] to [16], wherein the heating rate when sintering the electroconductive composition is 1 to 10°C/min.
• [18] Use of the electrically conductive composition according to any one of paragraphs [1] to [13] for forming an adherend of components, an electrically conductive layer or a circuit.
• [19] A sintered compact or bonded compact containing electrically conductive fillers and resin particles, the sintered compact or bonded compact being obtained by sintering the electrically conductive composition according to any one of [1] to [13], based on the sectional area of the sintered compact or joining part, the proportion of electrically conductive fillers is 60 to 95% by area, the proportion of resin particles is 1 to 35% by area, the proportion of components other than the resin particles and the electrically conductive fillers and the intermediate gaps is 4 to 25% by area %, and the mean particle diameter of the resin particles is 2 to 15 µm.
• [20] Component with a sintered part or joining part according to Section [19].

[Effects of the Invention]

According to the invention, by applying an electrically conductive composition to a component, preferably an electronic component, more preferably an electronic component for mounting in vehicles or an electronic component for communication devices, and by sintering the electrically conductive composition, so that the maximum Feret diameter of the in of the resin particles contained in the electrically conductive composition before sintering is below a certain rate of change, a sintered part can be obtained which has high electrical conductivity and thermal conductivity, and even if it is a large-area component, e.g. B. is a silicon chip, is less susceptible to detachment from an adherend after sintering or heat setting of the electrically conductive composition.

character list

• 1 shows the view of a component with a joining part in which an electrically conductive composition according to the prior art is used.
• 2 shows the view of a component with a joining part in which an electrically conductive composition according to the prior art is used.
• 3 shows the view of a component with a joining part in which an electrically conductive composition according to the invention is used.
• 4 shows the view of the measurement of the Feret diameter for particles of different shapes.
• 5 Fig. 12 shows the view of the results of DSC (Differential Scanning Calorimetry) measurement of the resin particles.
• 6 Fig. 12 shows the view of the results of the DSC measurement of the resin particles.
• 7 Fig. 12 shows the view of the results of the DSC measurement of the resin particles.
• 8th Fig. 12 shows the view of the results of the DSC measurement of the resin particles.
• 9 Figure 12 shows electron micrographs of prior art resin particles before and after heating.
• 10 Fig. 12 shows electron micrographs of the resin particles of the present invention before and after heating.
• 11 12 shows electron micrographs of the cut surface of the electroconductive composition of the present invention and the comparative example after sintering.
• 12 Fig. 12 shows the view of pore distribution and cracks of the electrically conductive composition according to the invention after sintering.

[Embodiments of the invention]

The electroconductive composition of the present invention contains electroconductive fillers and micrometer-sized particles composed of a resin, etc., the particles before and after heating or sintering the electroconductive composition having a rate of change in maximum Feret diameter of less than 1.20 % having. In the present invention, the rate of change of the maximum Feret diameter of the resin particles before and after the sintering is preferably less than 1.10 from the viewpoint of the peeling strength, and is more preferably in the range of 0.9 to 1.0. That is, the particles used in the electroconductive composition of the present invention, which are made of resin, etc., are particles whose original shape can be substantially retained at the temperature at which the electroconductive composition is sintered or thermoset. without the particles being melted and deformed.

In general, there are different description methods for specifying the size of the particles. When the particle shape is spherical, the particle diameter refers to the diameter, however, with a polygonal particle or particle with a distorted shape, it is not always possible to define the particle diameter in the same way as with spherical particles. As a criterion for defining the particle diameter of a polygonal particle, there is the unidirectional particle diameter. The unidirectional particle diameter is a particle diameter that can be analyzed by microscopic observation of a projection image of the particle, which includes Feret's diameter. The Feret diameter is expressed by a straight line connecting any two points on the contour of the selected particle, in other words, by the length of a perpendicular line pinched by two parallel lines in a given direction, the longest of these lines or perpendicular lines is denoted as the maximum Feret diameter, and the shortest is denoted as the minimum Feret diameter. The maximum Feret diameter is also known as the maximum thickness length (maximum caliper). The measurement of the Feret diameter of the resin particles of the present invention can be made by observing the cut surface of a member to which the electroconductive composition is applied, for example, with a scanning electron microscope (SEM) or an optical microscope with a high magnification (digital microscope) and from from the images obtained, the contour of the particles is specified using the image analysis software Image-J, and 100 to 200 particles are selected from which the shape of the particles can be positively confirmed.

According to the invention, the rate of change in the maximum Feret diameter of the particles can be calculated according to the following equation by taking the average value of the maximum Feret diameter of the particles before sintering the electrically conductive composition and the average value of the maximum Feret diameter of the particles after sintering the electrically conductive composition: rate of change of maximum Feret diameter = mean value of maximum Feret diameter after heating or sintering / mean value of maximum Feret diameter before heating or sintering In 4 a particle surrounded by a solid line is polygonal, and a particle surrounded by a dotted line is circular or oval. The circle-equivalent diameters of the particle surrounded by the solid line and the particle surrounded by the dotted line are the same. 4 shows as an example the major axis 15, the minor axis 11, the maximum Feret diameter 14 and the minimum Feret diameter 10. As can be seen from the illustration in FIG 4 is clear, when the particle is compared to other particles of the same circular equivalent diameter, the maximum Feret diameter of a particle does not necessarily coincide with the major (major) axis of such particle, and the minimum Feret diameter of a particle does not necessarily coincide with the minor (minor) axis of the particle.

The micron-sized particles composed of a resin, etc., used in the present invention may be composed of a resin such as a thermoplastic resin, a thermosetting resin, a silicone resin, etc., or another material capable of absorbing stress, e.g. B. of an inorganic material such as tin, gold or an alloy of tin and gold, as long as the rate of change of the maximum Feret diameter of the particle before and after sintering the electrically conductive composition is less than 1.20, preferably 0.9 to 1, 1, more preferably 1.0, ie the requirement that the maximum Feret diameter of the particles does not change substantially is met. The person skilled in the art can, taking into account the intended use of the electrically conductive together setting, the method of application and the desired physical properties, e.g. B. thermal conductivity, electrical conductivity, etc., select a suitable material.

The above particles are preferably resin particles from the viewpoint of peeling strength. When resin particles are used, under conditions where the electroconductive composition is sintered considering the sintering temperature of the electroconductive composition and the melting point of the resin, a resin whose rate of change of the maximum Feret diameter of the particle is 1.20, preferably should be selected 0.9 to 1.1, more preferably not exceeding 1.0.

The temperature at which the electroconductive composition is sintered depends on the electroconductive fillers used, the kind of resin particles and the particle diameter, but usually ranges from 80°C to 300°C. When the sintering temperature is lower than the temperature around 80°C, the electroconductive composition does not harden, and when the sintering temperature exceeds about 300°C, the resin particles melt and deform, or the molten resin flows into voids or pores, so that the Effects of the present invention are not obtained. The sintering of the electrically conductive composition can also take place in two stages at different temperatures. When using resin particles, the electrically conductive composition can, for example, in the first stage (pre-firing) at a temperature of about 80 to 200° C., advantageously about 130 to 200° C., more advantageously about 140 to 180° C. for a certain period of time heated and held, and then in the second stage (sintering), the sintering can also be at a higher temperature than the above temperatures, e.g. B. at greater than or equal to 150 ° C, advantageously at greater than or equal to 180 ° C, and even more advantageously at greater than or equal to 200 ° C. The heating rate in the pre-firing and sintering is usually 1 to 10°C/min, preferably 3 to 7°C/min, and more preferably 5°C/min. The heating rate up to the first stage (pre-firing) and the heating rate from the first stage (pre-firing) to the second stage (sintering) need not be the same. The sintering can be carried out under an air or inert gas atmosphere, e.g. B. under a nitrogen atmosphere. If the surface of the component to be joined is a material that easily forms an oxide film, e.g. e.g. copper, it is preferred to carry out the sintering under an inert gas atmosphere, e.g. B. under nitrogen purge to avoid the formation of an oxide film or discoloration. In this case, the oxygen concentration under a nitrogen atmosphere is less than or equal to 500 ppm, preferably less than or equal to 80 ppm, and more preferably less than or equal to 50 ppm from the viewpoint of preventing oxidation or discoloration of the surface of the member to be joined. Oxidation or discoloration of the copper with the above oxygen concentration does not substantially occur. However, when oxygen is present at a concentration of about 0.1% (1000 ppm), discoloration of the copper is observed. Furthermore, if oxygen is present at about 0.1% under a sintering atmosphere, the combustion of organic matter such as e.g. B. additives, which are contained in the electrically conductive composition. When the oxygen concentration under the sintering atmosphere exceeds 0.1%, the sintering result is the same as that of sintering under an air atmosphere. In this case, the copper will be completely discolored. The time to sinter the electrically conductive composition is typically between 15 and 180 minutes. The time for sintering the electrically conductive composition is not particularly limited as long as the electrically conductive composition is heat-cured and a sintered part is obtained. if e.g. For example, if sintering takes place after pre-firing, the respective sintering times can be 15 to 120 minutes, preferably 30 to 90 minutes and more preferably 60 minutes from the point of view of process control. In addition to or instead of the pre-firing, the sintering can also be carried out in that the heating is carried out at a constant heating rate, e.g. B. 1 to 10 ° C / min, preferably 3 to 7 ° C / min, and after reaching the sintering temperature, the sintering temperature is maintained for a certain time. In this case, the sintering time is z. B. 30 to 180 minutes, preferably about 60 to 120 minutes. The temperature, the heating or heating rate and the sintering atmosphere during sintering can vary depending on the type of electrically conductive fillers and resin particles used in the electrically conductive composition, the particle diameter, solvents and additives such as other resins and the material of the component to be joined and be selected by those skilled in the art according to the circumstances on the basis of the above information.

[Electrically Conductive Fillers (A) Silver Microparticles]

The electrically conductive composition according to the invention contains silver microparticles in nanometer size, advantageously silver microparticles with an average particle diameter of 10 to 300 nm, as the electrically conductive fillers (A).

The average particle diameter of the silver microparticles (A) of the present invention is preferably 20 to 180 nm, more preferably 30 to 170 nm, still more preferably 40 to 160 nm from the viewpoint of sinterability. When the average particle diameter of the silver microparticles (A) is less than 10 nm and the silver microparticle (A) has a coating on the surface, removal of the coating may become difficult and thus sintering may be disturbed. If the mean particle diameter of the silver microparticles (A) exceeds 300 nm, sintering may be disturbed due to a correspondingly decreasing specific surface area.

The tap density of the silver microparticles (A) is not particularly limited, but is preferably greater than or equal to 4 g/cm ³ , more preferably greater than or equal to 5 g/cm ^{3 , and still more preferably greater than or equal to 4 g/cm 3} from the viewpoint of sinterability of the electroconductive composition equal to 5.5 g/cm ³ . From the viewpoint of avoiding precipitation of the silver microparticles (A) when storing the electroconductive composition for a long period of time, the tap density is preferably less than or equal to 8 g/cm ³ , more preferably less than or equal to 7.5 g/cm ³ , and still more preferably less than or equal to 7 g/cm ³ . The tap density of the silver microparticles (A) can e.g. B. can be calculated by measurement according to the method for measuring the tap density of metal powder according to JIS standard Z2512:2012.

The shape of the silver microparticles (A) is not particularly limited and can be, for. B. flaky, plate-shaped, spherical, cubic or rod-shaped. When the silver microparticles (A) are flaky or plate-shaped, a sintered compact excellent in electrical conductivity and/or thermal conductivity is obtained after sintering the electrically conductive composition. Since the flaky or plate-like silver microparticles are sintered mainly in the minor axis direction, the internal stress is smaller than when using spherical silver microparticles, and a sintered part excellent in reflectivity is obtained by highly orienting the silver microparticles. Further, since the flaky or plate-like silver microparticles are less affected by the presence of oxygen, the sintering can be performed either under air atmosphere or inert gas atmosphere such as nitrogen. In the control of the oxygen concentration under a sintering atmosphere, sintering is carried out with an oxygen concentration of e.g. B. 1000 ppm, preferably 500 ppm, more preferably 80 ppm, and most preferably 50 ppm. Also, the pre-firing before the sintering can be carried out under an air atmosphere or an inert gas atmosphere, or under an inert gas atmosphere having the same oxygen concentration as mentioned above.

The surface of the silver microparticles (A) can also be coated. As a coating agent for such a coating z. B. amines, carboxylic acids, etc., although these are well known to those skilled in the art. A coating agent of carboxylic acids is preferable from the viewpoints of facilitating the curing of the electroconductive composition after sintering and improving the heat dissipation of the sintered compact because it can be easily eliminated at the time of sintering. As carboxylic acids z. B. monocarboxylic acids, polycarboxylic acids and oxycarboxylic acids, etc. can be mentioned. As the carboxylic acid, saturated and/or unsaturated fatty acids having a carbon number of 12 to 24 are preferable from the viewpoint of dispersibility into the resin or solvent.

One coating agent can be used, or two or more coating agents can be used together. As a method for coating the silver microparticles (A) with the coating agent, e.g. Examples include stirring and mixing the silver microparticles (A) and the coating agent in a mixer, impregnating the silver microparticles (A) in a solution of the coating agent, etc., although these are known to those skilled in the art.

The content of silver microparticles (A) in the electroconductive composition of the present invention is not particularly limited, but is preferably 5 to 50% by mass from the viewpoint of suppressing shrinkage due to sintering, and from the viewpoint of improving electroconductivity and/or or the thermal conductivity more preferably 10 to 40% by mass, particularly preferably 15 to 35% by mass, based on the total mass of the electrically conductive composition.

[Electrically Conductive Fillers (B) Metal Particles]

Electrically conductive composition according to the invention also contains, as electrically conductive fillers (B), metal particles of micrometer size, advantageously metal particles with an average particle diameter of 0.5 to 10 μm.

The average particle diameter of the metal particles (B) according to the invention is preferably 0.6 to 8 μm, more preferably 0.7 to 7 μm, and even more preferably 0.8 to 6 μm from the viewpoint of the rheology of the electrically conductive composition. If the average particle diameter of the metal particles (B) is less than 0.5 μm, the effect of suppressing shrinkage upon sintering of the electroconductive composition is reduced and the adhesion between the bonded member and the sintered part is reduced. If the average particle diameter of the metal particles (B) exceeds 10 μm, the sinterability of the electroconductive composition is deteriorated, thereby reducing the adhesion between the bonded member and the sintered member.

The mean particle diameter distribution of the metal particles (B) may have a single peak or multiple peaks.

The BET specific surface area of the metal particles (B) is not particularly limited, but is preferably 0.1 to 3 m ² /g, more preferably 0.2 to 2 m ² /g, and still more preferably 0.3 to 1 m ² /G. From the viewpoint of ensuring a surface area in contact with the adhered member, the BET specific surface area of the metal particles (B) is preferably greater than or equal to 0.1 m ² /g. From the viewpoint of reducing the use amount of (D) binder resin and/or solvent, which will be described later, the BET specific surface area of the metal particles (B) is preferably less than or equal to 3 m ² /g. The BET specific surface area of the metal particles (B) can be measured by the BET 1-point method using a BET specific surface area measuring device.

The tap density of the metal particles (B) is not particularly limited, but is preferably greater than or equal to 4 g/cm ³ , more preferably greater than or equal to 5 g/cm ³ , and still further from the viewpoint of adhesive strength of the electroconductive composition to the adhered member preferably greater than or equal to 5.5 g/cm ³ . From the viewpoint of avoiding precipitation of the metal particles (B) when storing the electroconductive composition for a long period of time, the tap density is preferably less than or equal to 8 g/cm ³ , more preferably less than or equal to 7.5 g/cm ³ , and still more preferably less than or equal to 7 g/cm ³ . The tap density of the metal particles (B) can, for. B. can be calculated by measurement according to the method for measuring the tap density of metal powder according to JIS standard Z2512:2012.

The shape of the metal particles (B) is not particularly limited and can, for. B. flaky, plate-shaped, spherical, cubic or rod-shaped. When the flake or plate form is employed as the form of the metal particles (B), a sintered compact excellent in electrical conductivity and/or thermal conductivity is obtained after sintering the electrically conductive composition. Since flaky or plate-shaped metal particles are sintered mainly in the minor axis direction, the internal stress is smaller than when spherical silver microparticles are used, and a sintered part excellent in reflectance is obtained by highly orienting the metal particles. Further, since the flaky or plate-like metal particles are less affected by the presence of oxygen, the sintering can be performed under an inert gas atmosphere such as nitrogen.

The metal constituting the metal particles (B) of the present invention is not particularly limited as long as it can contribute to the electrical conductivity of the sintered compact. Metals that can contribute to the electrical conductivity can be metals well known to those skilled in the art, such as silver, copper, nickel, aluminum, chromium, gold, platinum, palladium, tungsten, molybdenum, etc., as individual metals, as mixtures, as alloys and/or used as oxides. The alloys of the above metals may be binary or ternary alloys, and the alloys may also contain elements other than the above metals. Carbon nanotubes can also be used as the material constituting the metal particles (B). Furthermore, the metal particles (B) may be a mixture of two or more kinds.

The ratio of the silver microparticles (A) and metal particles (B) in the electroconductive composition of the present invention is not particularly limited, but is preferably in the range of 5:95 to 60:40, more preferably in the range from the viewpoint of balance between thermal conductivity and joining properties from 10:90 to 50:50, and more preferably in the range from 15:85 to 40:60 in mass ratio.

[(C) resin particles]

In the present invention, (C) resin particles having an average particle diameter of 2 to 15 μm are used as the particles having the above Feret maximum diameter change rate.

From the viewpoint of stress relaxation and suppression of crack propagation in the sintered part after sintering the electroconductive composition, the average particle diameter of the resin particles (C) is preferably greater than or equal to 3 μm, and more preferably greater than or equal to 4 μm. From the viewpoint of stress distribution in the sintered compact and the thickness of the sintered compact after sintering the electroconductive composition, the average particle diameter of the resin particles (C) is preferably less than or equal to 13 μm, and more preferably less than or equal to 12 μm. If the average particle diameter of the resin particles (C) is too large, the number of resin particles (C) per volume of the electroconductive resin composition becomes small and uniform distribution of the resin particles (C) becomes difficult, thereby impairing the stress dispersing effect. If the average particle diameter of the resin particles (C) is large, the thickness of the sintered compact cannot be reduced adequately, so that the heat generated from the bonded component cannot be dissipated efficiently.

When joining components, the thickness of the joining part can be a maximum of about 200 µm depending on the intended use, but is usually between 10 µm and 50 µm. Therefore, considering the shrinkage rate of about 15% that occurs when the electroconductive composition is thermoset, the average particle diameter of the resin particles (C) is in the viewpoint of a uniform distribution of the resin particles (C) and a uniform relaxation and distribution of the stress Joining part and thus the suppression of detachment preferably in the range of less than or equal to 85% of the thickness of the joining part after heat curing.

The shape of the resin particles (C) is preferably spherical or substantially spherical, but may be cubic, columnar, prismatic, conical, pyramidal, flaky and so on.

The melting point of the resin particles (C) is preferably higher than the sintering temperature of the electroconductive composition or the electroconductive fillers from the viewpoint of the rate of change of the maximum Feret diameter, and is 140 to 250°C, preferably 170°C to 250°C. According to the invention, it has surprisingly been found that the sintering conditions are controlled in such a way that when joining the component to be bonded, e.g. a substrate with a chip using an electroconductive composition containing electroconductive fillers and resin particles as adhesives, the rate of change of the maximum Feret diameter of the resin particles in the electroconductive composition is 1.20 or less, preferably 0.9 to 1.1, more preferably 1.0, whereby a more reliable sintered part or joined part is obtained as a joined part or a joining method according to the prior art. Accordingly, the present invention provides: a method for joining a component to be bonded, e.g Joining part obtained by sintering or heat curing of the electrically conductive composition, and a component with the sintering part or joining part, in particular an electronic component, e.g. B. a component for assembly in vehicles or communication devices.

As the resin constituting the resin particles (C), a resin selected from the group consisting of the thermoplastic resin, thermosetting resin and silicone resin can be used. As the above resin, resins well known to those skilled in the art can be used. As the thermoplastic resin, particles of polyamides, e.g. B. nylon resins such as nylon 11, nylon 12 and nylon 6, AS resin, ABS resin, AES resin, vinyl acetate resin, polystyrene, polyolefin resins such as polyethylene and polypropylene, polyvinyl chloride, acrylic resin, methacrylic resin, polyvinyl alcohol resin, polyvinyl ether, polyacetal, polycarbonate, polyethylene terephthalate , polybutylene terephthalate, polyvinyl butyral, polysulfone, polyetherimide ethyl cellulose, cellulose acetate, various fluororesins, polyolefin elastomer, saturated polyester resin, etc.

As thermosetting resins z. B. urea resin such as polyurethane resin, polyimide resin, phenolic resin, epoxy resin, melamine resin, unsaturated polyester resin and alkyd resin are mentioned.

Silicone resins are also called silicone polymer and represent a series of resins with organopolysiloxane as the main chain.

The above resins constituting the resin particles (C) may be used alone or in combination with two or more of the above resins. It can also be a homopolymer of a single monomer or a copolymer of two or more monomers that make up the resin.

From the viewpoint of effectively preventing the sintered compact from detaching from the bonded compact, resin particles having a melting point or DSC peak of between 140 and 250°C, preferably 170 to 250°C are preferable. As resin particles with a melting point in the range from 140 to 250 ° C z. B. nylon 12, nylon 11, nylon 6, polyethylene, polypropylene, vinyl acetate resin, saturated polyester resin, etc. Among them, nylon 12, nylon 11, nylon 6 and polyethylene are more preferably used, nylon 12, nylon 11 and nylon 6 are more preferably used, and nylon 12 and nylon 11 are more preferably used.

According to the present invention, the resin particles (C) can also be made at a temperature of 80°C or more and 300°C or less, preferably 140°C or more and 250°C or less by controlling the conditions when sintering the electroconductive composition , more preferably also at a temperature of greater than or equal to 165° C., at which the electrically conductive composition is sintered, the particle shape before sintering being essentially retained. Accordingly, the rate of change of the maximum Feret diameter of the resin particle after sintering relative to the maximum Feret diameter of the resin particle before sintering of the electroconductive composition is less than 1.20, preferably from 0.9 to 1.1, and more preferably 1. 0 As conditions for sintering the electrically conductive composition, the sintering temperature, the sintering time and the sintering atmosphere are given. If the sintering is divided into pre-firing and sintering, a component to which the electrically conductive composition of the present invention is applied is heated to a predetermined pre-firing temperature at a specific heating rate, and after reaching the pre-firing temperature for a specific time, e.g. B. from 15 minutes to 90 minutes, preferably 30 minutes to 60 minutes, heated at the predetermined pre-firing temperature. After pre-firing, the component to which the electrically conductive composition is applied is then heated to the sintering temperature at a specific heating rate, and after the sintering temperature has been reached over a specific time, e.g. B. from 15 minutes to 90 minutes, preferably 30 minutes to 60 minutes, heated at the predetermined sintering temperature. Alternatively, the electrically conductive composition can be sintered by heating to the predetermined sintering temperature at a specified heating rate without pre-firing. Pre-firing here means heating and keeping at a certain temperature, not necessarily sintering. Pre-firing and sintering can be carried out under an inert gas atmosphere, e.g. B. under nitrogen atmosphere with an oxygen concentration of less than or equal to 1000 ppm, preferably less than or equal to 500 ppm, more preferably less than or equal to 80 ppm, most preferably less than or equal to 50 ppm. By sintering the electrically conductive composition under the above conditions, the resin particles contained in the electrically conductive composition retain substantially the original shape before sintering without being melted during sintering and filling gaps in the sintered part as in the method according to in the prior art, and these are evenly distributed in the electroconductive resin composition before and after the heating or sintering, so that the stress in the sintered compact or joined compact obtained after the sintering is reduced and diffused . In addition, the sintered part or the joining part after sintering the electrically conductive composition in the prior art method no longer has the particle diameter of the resin particles before sintering, since the resin particles melted during sintering and penetrated into intermediate gaps of the sintered part during the method of the present invention, the mean particle diameter of the resin particles (C) after sintering substantially retains the original value, 2 to 15 µm. Therefore, in comparison with a joint obtained by a prior art electroconductive composition, the propagation of cracks in the joint is avoided even in the case of a member having a large area, and thus detachment of bonded parts and joints, e.g. B. between a silicon chip and the part to be joined or between the part to be joined and a lead frame or a substrate. In this way, an electronic component with high joining reliability, preferably an electronic component with excellent joining reliability with the joining partner, specifically an electronic component for assembly in vehicles or for communication devices with excellent joining reliability with the joining partner is obtained.

The content of resin particles (C) in the electroconductive composition is preferably greater than or equal to 0.1% by mass, more preferably greater than or equal to, from the viewpoint of effectively preventing detachment of the sintered compact from the bonded compact after cold/heat cycle 0.5% by mass, more preferably greater than or equal to 1% by mass, and particularly preferably greater than or equal to 2% by mass, based on the mass of the electrically conductive composition. The content of the resin particles (C) is preferably less than or equal to 10% by mass, more preferably less than or equal to 7% by mass, and still, from the viewpoint of preventing the reduction in thermal conductivity of the sintered compact or adherend after curing of the electroconductive composition more preferably less than or equal to 5% by mass based on the mass of the electrically conductive composition.

In the present specification, the mean particle diameter of the metal particles (B) and the resin particles (C) is the particle diameter whose cumulative volume percent measured with a laser diffraction and scattering particle size analyzer is 50% by weight (50% mean particle diameter of the particle diameter distribution) (D50). For such measurements z. For example, Laser Diffraction and Scattering Particle Size Analyzer MT-3000 manufactured by Nikkiso Co., Ltd. can be used. The mean particle diameter of the silver microparticles (A) is the 50% mean particle diameter (D50) of the particle diameter distribution measured by dynamic light scattering. Such particle diameters can e.g. B. can be measured with the Nanotrac particle size distribution measuring device, manufactured by Nikkiso Co., Ltd..

The melting point of the resin particles (C) is determined depending on the type of resin and is well known to those skilled in the art. To measure the melting point of the resin z. B. a differential scanning calorimeter (DSC) can be used. In 5 until 8th DSC peaks of the resin particles (c1), (c3), (c4) and (c11) listed in Table 1 are shown, respectively.

The electroconductive composition of the present invention may contain any of the following components in addition to silver microparticles (A), metal particles (B) and resin particles (C).

[(D) Binder Resin]

The electroconductive composition of the present invention may further contain a binder resin (D) as occasion demands. In addition, containing the binder resin (D) can impart fluidity and adhesiveness to the electroconductive composition. The binder resin (D) may be used alone from the viewpoint of workability, or as long as it is liquid after dissolving in a solvent, thermoplastic resins such as e.g. B. polyolefin, polyvinyl butyral, polyvinyl alcohol, ethyl cellulose, saturated polyester resin, acrylic resin, etc., thermosetting resins such as. B. epoxy resin, phenol resin, urethane resin and polyimide resin, etc., or silicone resins can be used, although they are not particularly limited. These resins can be used alone or in combination of two or more kinds. From the viewpoint of heat resistance, since the sintering temperature is high, the binder resin (D) is preferably a thermosetting resin, and particularly preferably an epoxy resin.

The content of the binder resin (D) is less than or equal to 10% by mass, more preferably less than or equal to 8% by mass, and still more preferably less than or equal to 6% by mass based on the mass of the electroconductive composition. When the content of the binder resin (D) is less than or equal to 10% by mass based on the mass of the electroconductive composition, a network by constriction of silver microparticles (A) and/or metal particles (B) is easier to form, and a stable electrical Conductivity and thermal conductivity are preserved. Further, the binder resin is preferably used in an amount of greater than or equal to 0.5% by mass based on the mass of the electroconductive composition from the viewpoints of fluidity and adhesiveness.

<hardener>

In addition to the above components, the electroconductive composition of the present invention may also contain a curing agent. As a curing agent z. Examples include amine-based curing agents such as tertiary amines, alkyl ureas and imidazoles, and phenol-based curing agents.

The content of curing agent is less than or equal to 2% based on the mass of the electrically conductive composition. In this way, the residue of the uncured curing agent becomes less and the adhesion with the component to be bonded becomes better.

<Curing Accelerator>

The electroconductive composition of the present invention may additionally contain a curing accelerator. As the curing accelerator, for example, imidazoles such as 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-methyl-4-methylimidazole, 1-cyano-2-ethyl-4-methylimidazole, etc. , tertiary amines, triphenylphosphines, urea-based compound, phenols, alcohols and carboxylic acids, etc. Two or more kinds of curing accelerators can be used in combination.

When a curing accelerator is used, its content is usually less than or equal to 0.5% by mass based on the mass of the electroconductive composition.

<Solvent/Diluent>

The electrically conductive composition according to the invention can additionally contain a solvent or diluent in order to process the electrically conductive composition into a paste and to facilitate application. When a solvent or diluent is used, a solvent or diluent which does not dissolve the resin particles is used in order that the shape of the resin particles can be maintained in the paste. As for the other points, the solvent or diluent to be used is not particularly limited, but from the viewpoint of volatility upon sintering, a solvent or diluent having a boiling point of 350°C or less is preferred, and a solvent or diluent having a Boiling point of less than or equal to 300°C is more preferable. As a solvent or diluent, the substances well known to those skilled in the art, such as. As acetates, ethers and hydrocarbons, specifically dibutyl carbitol and butyl carbitol acetate, can be used.

The content of the solvent or diluent is usually less than or equal to 15% by mass, and preferably less than or equal to 10% by mass, based on the electroconductive composition from the viewpoint of workability.

<Additives>

In addition to the components mentioned above, the electrically conductive composition according to the invention can also contain additives well known to those skilled in the art, such as e.g. B. antioxidant, UV absorber, tackifier, viscosity adjuster, dispersant, coupling agent, toughening agent and elastomer, etc., as far as the effects of the present invention are not impaired.

The electroconductive composition of the present invention can be prepared by mixing and stirring the above silver microparticles (A), metal particles (B), resin particles (C) and binder resin (D) as needed and other components as needed in any order. As a method for this, for example, methods well known to those skilled in the art, such as B. two-roll mill, three-roll mill, sand mill, roller mill, ball mill, colloid mill, jet mill, bead mill, kneader, homogenizer and impellerless mixer can be applied.

According to the invention, a sintered part is obtained by applying the electrically conductive composition according to the invention to a component and sintering or heat treatment, which has high electrical conductivity and thermal conductivity and is less susceptible to detachment of the component to be bonded. The electroconductive composition of the present invention contains at least the electroconductive fillers and the resin particles, and it has been found that the electroconductive composition is applied to the member and sintered under conditions where the rate of change of the maximum Feret diameter of the resin particles after sintering based on the maximum Feret diameter of the resin particles before sintering is less than 1.20, preferably in the range of 0.9 to 1.1 and even more preferably 1.0, the electrically conductive composition is sintered, whereby the detachment in particular of chips with a large area, e.g. B. chips with a size of 7 × 7 mm or 8 × 8 mm surprisingly can be effectively prevented. In the sintered part obtained according to the invention of the present application, the proportion of electrically conductive fillers (metal surface) is 60 to 95 area % based on the cut surface and the proportion of resin particles (resin particle area) is 1 to 35 area %. The remaining 4 to 25% by area (other area) are residues from gaps, binder resin, etc. The "residues from binder resin, etc." B. from resin particles (C), by heating and sintering partially melted, and additives such as curing agent, curing accelerator, antioxidant, UV absorber, tackifier, viscosity adjuster, dispersant, coupling agent, toughener, and elastomer or solvent. As stated above, according to the present invention, the rate of change of the maximum Feret diameter of the resin particles in the electroconductive composition after sintering is less than 1.20, the resin particles are not substantially deformed during sintering, so that the average particle diameter before sintering is maintained . The protruding metal surface, the surface of the resin particles and other surfaces are obtained by observing the cut surface of the sintered compact by SEM.

Consequently, the subject matter of the present invention is a sintered part or joined part, which is obtained by sintering the electrically conductive composition according to the method according to the invention, and a component with the sintered part or joined part, preferably an electronic component with the sintered part or joint part, more preferably an electronic component with the sintered part or joining part for assembly in vehicles or for communication devices.

Next, examples of the method of using the electroconductive composition of the present invention will be explained.

If the electrically conductive composition according to the invention on components such. B. silicon chips, electronic components for assembly in vehicles, etc., by those skilled well-known methods, such. B. Dispensing, metal mask, screen printing, spin coating, etc. is applied to form a layer of the electrically conductive composition, and then the electrically conductive composition is used to bond a component, the component is placed in such a way that the layer of electrically conductive composition is in contact with the joining partner (e.g. a lead frame) of the component, and then under the conditions where the rate of change of the maximum Feret diameter of the resin particles after sintering with respect to the maximum Feret diameter of the resin particles before Sintering is less than 1.20, the electrically conductive composition is heat-treated (sintered), whereby the electrically conductive composition of the present invention becomes a member having the sintered part or bonded part, which has high electrical conductivity and thermal conductivity and is resistant to peeling due to repetitive Less susceptible to cold/heat cycles, even if the component has a large area.

The temperature at which the electroconductive composition of the present invention is sintered is not particularly limited as long as the electroconductive composition is thermoset; H. is sintered, but temperatures in the range of 80°C to 300°C are advantageous. The heating rate is usually 1 to 10°C/min, preferably 3 to 7°C/min, and more preferably 5°C/min. The sintering of the electrically conductive composition can also take place in two stages. For example, in the first stage (pre-firing), sintering occurs at a relatively low temperature, e.g. B. 80 to 200 ° C, advantageously 130 to 200 ° C, more advantageously 140 to 180 ° C and in the subsequent second stage (sintering), the sintering z. B. at a higher temperature than in the first stage, z. B. at greater than or equal to 150 ° C, advantageously greater than or equal to 180 ° C, and more advantageously greater than or equal to 200 ° C, in order to stabilize the shape as a sintered part or joined part.

In order to avoid a state in which the sintered part or the joined part shrinks and becomes too hard due to an excessive progress of the connection of the silver microparticles (A) and/or the metal particles (B), the sintering temperature is preferably lower than or equal to 300° C. more preferably less than or equal to 275°C, and even more preferably less than or equal to 250°C.

The time for heating the electroconductive composition is not particularly limited as long as the electroconductive composition is sintered and the sintered part or the bonded part is obtained, but it is usually 15 minutes to 180 minutes.

The heating can be done in air or in an inert gas atmosphere such as argon or nitrogen. Heating in air facilitates removal of the coating agent on the surface of the silver microparticles (A) and hence sintering, but the silver microparticles (A) and/or the metal particles (B) are easily oxidized and an oxide film is formed, posing a danger that the electrical conductivity and thermal conductivity of the resulting electrically conductive, cured adhesive can be impaired. If a member to be bonded (e.g., Cu substrate) that is easily oxidized when heated in air is used, joining may be disturbed by, for example, oxidation of the member to be bonded or the member to be adhered may be discolored, and there is also a fear that the surrounding members, which are easily oxidized, will oxidize and deteriorate.

Therefore, in order to avoid the occurrence of the above problems, it is preferable to carry out the heating in an inert gas atmosphere, e.g. B. in a nitrogen atmosphere to make. When sintering is performed in a nitrogen atmosphere, the oxygen concentration in the nitrogen atmosphere is less than or equal to 1000 ppm, preferably less than or equal to 500 ppm, more preferably less than or equal to 80 ppm, and most preferably less than or equal to 50 ppm. The oxygen concentration in the nitrogen atmosphere during sintering can also be 0 ppm.

To the bonded component, z. B. to efficiently dissipate heat generated by a semiconductor device, the layer of the electrically conductive composition is preferably thin. For example, the thickness of the electrically conductive composition after sintering is preferably less than or equal to 50 μm, more preferably less than or equal to 40 μm, and even more preferably less than or equal to 30 μm.

On the other hand, a thicker layer of the electrically conductive composition is desirable in order to relieve internal stresses that are due to the difference in thermal expansion coefficients between the component to be bonded, e.g. B. a substrate, and the sintered part to attenuate in the direction of the thickness of the sintered part. Specifically, the thickness of the electrically conductive composition after sintering is preferably greater than or equal to 5 μm, more preferably greater than or equal to 10 μm, and even more preferably greater than or equal to 20 μm.

According to the invention, the average particle diameter of the resin particles (C) should be selected according to the thickness of the layer of the electroconductive composition applied to the component, since the shape or particle diameter of the resin particles (C) is maintained at a certain rate of change after sintering . When the thickness of the electroconductive composition layer is large, resin particles (C) having a relatively large average particle diameter can be used, while when an electroconductive composition layer having a small thickness is desired, the average particle diameter of the resin particles (C) is preferably correspondingly small. The appropriate mean particle diameter of the resin particle (C) can be selected by those skilled in the art based on the purpose of use, the composition, the layer thickness, etc. of the electroconductive composition according to the circumstances.

The thermal conductivity of the sintered part or joined part obtained by sintering the electrically conductive composition according to the invention is preferably greater than or equal to 20 W/m·K, more preferably greater than or equal to 35 W/m·K, and even more preferably greater than or equal to 50 W/m K to ensure the thermal conductivity of the bonded component. As the method for calculating the thermal conductivity, the method given in the following working examples can be used.

As a method of evaluating that when a member to be bonded, such as B. an electronic component is bonded using the electrically conductive composition of the present invention, even in the cold / heat cycle, i. H. with repeated temperature changes from high and low temperatures, little detachment occurs, various methods are given. The methods specified in the following exemplary embodiments can be used, for. B. be used to perform a cold/heat cycle test and measure the percentage of detachment area after the test. When measured by this method, the peeling area ratio is preferably less than or equal to 20%, more preferably less than or equal to 15%, more preferably less than or equal to 10%, and most preferably less than or equal to 5% from the viewpoint of heat resistance.

[embodiments]

The present invention is explained in more detail by the following examples, but the present invention is not limited by these examples.

A. Preparation of the Electrically Conductive Compositions

Conductive compositions (Sample Nos. 1 to 28) were prepared by kneading with a three-roll mill using the materials listed below, each in the amounts (% by mass) shown in Table 2.

[(A) Silver microparticles]

• a1. Spherical particles, mean particle diameter d50 = 90 nm, manufactured by Tanaka Kikinzoku Kogyo K.K.
• a2. Spherical particles, mean particle diameter d50 = 150 nm, manufactured by Tanaka Kikinzoku Kogyo K.K.
• a3. Spherical particles, mean particle diameter d50 = 250 nm, manufactured by Tanaka Kikinzoku Kogyo K.K.

[(B) metal particles]

• b1. Flaky silver particles, average particle diameter d50 = 5.5 µm, tap density 7.0 g/cm ³ , manufactured by Tanaka Kikinzoku Kogyo KK
• b2. Flaky silver particles, average particle diameter d50 = 4 µm, tap density 6.7 g/cm ³ , manufactured by Tanaka Kikinzoku Kogyo KK
• b3. Spherical silver particles, average particle diameter d50 = 0.8 µm, tap density 5.5 g/cm ³ , manufactured by Tanaka Kikinzoku Kogyo KK
• b4. Spherical copper particles, average particle diameter d50 = 5 µm, tap density 5.0 g/cm ³ , manufactured by Mitsui Mining & Smelting Co., Ltd.

[(C) resin particles]

• c1. Silicone resin "KMP-600" manufactured by Shin-Etsu Silicone Co., Ltd. Rate of change of maximum Feret diameter at 165°C: 0.9
• c2. Thermoplastic resin "TR-1" (polyamide) manufactured by Toray Industries, Inc., Rate of change of maximum Feret diameter at 140°C: 1.01
• c3: Thermoplastic resin "PPW-5" (polypropylene) manufactured by Seishin Enterprise Co., Ltd., rate of change of maximum feret diameter at 140°C: 1.02, rate of change of maximum feret diameter at 165°C: 1 ,22
• c4. Thermoplastic resin particle “SP-500” (polyamide) manufactured by Toray Industries, Inc., rate of change of maximum feret diameter at 150°C: 1.02, rate of change of maximum feret diameter at 165°C: 0.96
• c5: Thermoplastic resin particle "SP-10" (polyamide) manufactured by Toray Industries, Inc.
• c6. Thermoplastic resin "SP500" (polyamide) classified, manufactured by Toray Industries, Inc.
• c7. Thermoplastic resin particle "SP-10" (polyamide) classified, manufactured by Toray Industries, Inc.
• c9. Thermoplastic Resin Particle (Comparative Example) "PM-200" (polyethylene) manufactured by Mitsui Chemicals, Inc.
• c10. Thermoplastic Resin (Comparative Example) "Oragasol 3501EXD" (polyamide) manufactured by ARKEMA.
• c11. Thermoplastic Resin (Comparative Example) "PW Powder" (polyester) manufactured by Tanaka Kikinzoku Kogyo K.K.

The various properties of the above resin particles are shown in Table 1 below: [Table 1] example resin particles (C) resin particles (c1) resin particles (c2) resin particles (c3) resin particles (c4) resin particles (c5) resin name KMP-600 TR-1 PPW-5 SP500 (Regular) SP10 (Normal) resin type silicone resin polyamide polypropylene 12 nylon 12 nylon particle diameter (d 50) 5µm 13 µm 5 µm 5 µm 10 microns DSC tip Without 210-220°C 142∼152°C 165∼175°C 165∼175°C particle shape Spherical Spherical indefinite shape Spherical Spherical Rate of change of maximum Feret diameter at sintering temperature Good Good Good Good Good [Table 1 continued] comparative example resin particles (c6) resin particles (c7) resin particles (c9) ( WO2016/063931 , resin of embodiment 15) Resin particles (c10) ( WO2016/063931 , resin of embodiment 12) resin particles (c11) SP500 (Classified) SP10 (Classified) PM-200 Oraqaso13501 EXD PW Powder (P01CW35) 12 nylon 12 nylon polyethylene nylon copolymer polyester 3 µm 15 µm 10 microns 10 microns 15 µm 165∼175°C 165∼175°C 130∼140°C 137∼147°C 70∼80℃ Spherical Spherical Spherical Spherical indefinite shape Good Good Bad Bad Bad

In "Rate of change in maximum Feret diameter at sintering temperature" of Table 1, the term "good" means that the rate of change in maximum Feret diameter after heating the electrically conductive composition under specified conditions compared to the maximum Feret diameter of the particle before Sintering was less than 1.2. The term "poor" means that the rate of change was greater than or equal to 1.20.

9 shows electron micrographs of the resin particles (c3) according to the prior art and 10 Fig. 12 shows electron micrographs of the resin particles (c1) according to the present invention before and after heating. In each view, the upper tier shows the state before heating (room temperature) and the lower tier shows the state after heating at 165°C for 30 minutes. Out of 9 it is clear that the particle shape of the resin particles PPW-5 of c3 changes greatly after heating, with the change rate of the maximum Feret diameter of the resin particles of c3 being 1.20. On the other hand, goes out 10 clearly shows that the KMP-600 resin particle of c1 substantially retains its original shape even after heating, with the rate of change of the maximum Feret diameter of the resin particle of c1 being 0.99.

[(D) Binder Resin]

• d1. "EPICLON 830-S" (liquid epoxy resin at room temperature) manufactured by Dainippon Ink and Chemicals, epoxy equivalence 169 g/eq.
• d2 “ERISYS GE-21” (room temperature liquid epoxy) manufactured by CVC, epoxy equivalence 125 g/eq.

In addition to the above (A) to (D), a phenol-based curing agent (MEH8000H, manufactured by Meiwa Plastic Industries, Ltd.), 2-phenyl-4,5-dihydroxymethylimidazole (2PHZ, curing accelerator, manufactured by Shikoku Chemicals Corporation), and as the solvent, dibutyl carbitol (Solvent 1 manufactured by Tokyo Chemical Industry Co., Ltd.) or butyl carbitol acetate (Solvent 1 manufactured by Tokyo Chemical Industry Co., Ltd.) is used.

B. Evaluation of physical properties

The electroconductive compositions obtained in A (Sample Nos. 1 to 28) were each coated on a 10×10 mm silver-plated copper lead frame, and a 5×5 mm or 7×7 mm silver-sputtered silicon chip was then placed on this coated surface. Under a nitrogen atmosphere, the temperature was raised from room temperature to 250°C at a heating rate of 3 to 7°C/min, and by heating for 60 minutes at this temperature, a metal joined body was obtained in which the copper lead frame and the silicon chip were replaced by the sinter-hardened electroconductive composition (Examples 1 to 21 and Comparative Examples 1 to 8). The thermal conductivity λ of the obtained metal joined body is shown in Table 2.

Regarding thermal conductivity λ (W/m·K), thermal diffusion a was measured with Laser Flash Heat Constant Meter TC-7000 (manufactured by ULVAC-RIKO, Inc.) according to ASTM-E1461, specific gravity d at room temperature was determined according to calculated by the pycnometer method, and the specific heat Cp at room temperature was measured with the differential scanning calorimeter DSC-7020 (Seiko Instruments & Electronics Ltd.) according to JIS-K7123 2012 and calculated from the relationship λ = a × d × Cp .

The obtained metal joined body was subjected to a cold/heat cycle test and the peeling area was measured. In the cold/heat cycle test, the metal joined body was held at -50°C for 30 minutes and then at 150°C for 30 minutes, and this treatment was regarded as one cycle and repeated for 2000 cycles. Then, the rate of peeling area of the silicon chip resulting after the cold/heat cycle test was measured. The peeling area ratio was determined by obtaining images of the peeled state of the metal adherend after the cold/heat cycle test with the ultrasonic image inspection machine Fine SAT (Hitachi Power Solutions Co., Ltd.) and shading these images with the binarization software Image-J converted into two levels, white and black, using the following relationship: $$\begin{array}{l}\text{Percentage of detachment area}\left(\%\right)=\text{OJ}\ddot{\text{O}}\text{solution flat}\left(\text{Number of black pixels}\right)\hfill \\ ÷\text{silicon chips}\ddot{\text{a}}\text{che}\left(\text{Number of black pixels}+\text{Number of white pixels}\right)\times \hfill \\ 100\hfill \end{array}$$

[Fortsetzung Tabelle 2] Ausführungsbeispiel 1 Ausführungsbeispiel 2 Ausführungsbeispiel 3 1 2 3 - 26,55 - 61,95 - 63,64 - 35,40 - - - - 26,55 26,55 27,27 - - - - - - 0,88 0,88 0,91 0,44 0,44 0,45 0,35 0,35 0,36 0,09 0,09 0,09 - - - 7,08 7,08 7,27 2,65 2,65 2,65 - - - - - - - - 130 130 90 Gut Gut Gut Gut Gut Gut [Fortsetzung Tabelle 2] Ausführungsbeispiel 4 Ausführungsbeispiel 5 Ausführungsbeispiel 6 4 5 6 - - - 63,64 62,78 61,95 - - - - - - 27,27 26,91 26,55 - - - - - - 0,91 0,90 0,88 0,45 0,45 0,44 0,36 0,36 0,35 0,09 0,09 0,09 - - - 6,36 6,73 7,08 - - - 0,91 1,79 2,65 - - - - - - - - - - - - - - - 150 140 125 Gut Gut Gut Gut Gut Gut [Fortsetzung Tabelle 2] Ausführungsbeispiel 7 Ausführungsbeispiel 8 Ausführungsbeispiel 9 7 8 9 - - 26,55 60,34 44,25 - - - 35,40 - - - 25,86 44,25 26,55 - - - - - - 0,86 0,88 0,88 0,43 0,44 0,44 0,34 0,35 0,35 0,09 0,09 0,09 - - - 7,76 7,08 7,08 - - - 4,31 2,65 2,65 - - - - - - - - - - - - - - - 80 155 140 Gut Gut Gut Gut Gut Gut [Fortsetzung Tabelle 2] Ausführungsbeispiel 10 Ausführungsbeispiel 11 Ausführungsbeispiel 12 10 11 12 29,13 21,51 26,79 - - - 38,83 53,76 35,71 - - - 19,42 10,75 26,79 - - - - - - 0,97 1,08 0,45 0,49 0,54 7,37 0,39 0,43 0,18 0,10 0,11 0,04 - - - 7,77 8,60 - - - - 2,91 3,23 2,68 - - - - - - - - - - - - - - - 125 110 150 Gut Gut Gut Gut Gut Gut [Fortsetzung Tabelle 2] Ausführungsbeispiel 13 Ausführungsbeispiel 14 Ausführungsbeispiel 15 13 14 15 26,79 27,03 - - - - 35,71 36,04 35,40 - - 26,55 26,79 27,03 26,55 - - - - - - - 1,80 0,88 - 0,90 0,44 - 0,72 0,35 - 0,18 0,09 - - - 8,04 5,86 7,08 - - - 2,68 0,45 2,65 - - - - - - - - - - - - - - - 200 130 100 Gut Gut Gut Gut Gut Gut [Fortsetzung Tabelle 2] Ausführungsbeispiel 16 Ausführungsbeispiel 17 Ausführungsbeispiel 18 16 17 18 26,55 26,55 26,55 - - - 35,40 35,40 35,40 - - - - - 26,55 26,55 - - - 26,55 - 0,88 0,88 0,88 0,44 0,44 0,44 0,35 0,35 0,35 0,09 0,09 0,09 - - - 7,08 7,08 7,08 2,68 - - 2,65 2,65 2,65 - - - - - - - - - - 80 100 125 Gut Gut Gut Gut Gut Gut [Fortsetzung Tabelle 2] Ausführungsbeispiel 19 Ausführungsbeispiel 20 Ausführungsbeispiel 21 19 20 21 - 26,55 - 61,95 - 61,95 - 35,40 - - - - 26,55 26,55 26,55 - - - - - - 0,88 0,88 0,88 0,44 0,44 0,44 0,35 0,35 0,35 0,09 0,09 0,09 - - - 7,08 7,08 7,08 - - - - 2,65 - - 2,65 - - 2,65 - - - - 130 140 100 Gut Gut Gut Gut Gut Gut [Fortsetzung Tabelle 2] Vergleichsbeispiel 1 Vergleichsbeispiel 2 Vergleichsbeispiel 3 22 23 24 26,55 26,55 - - - 63,64 35,40 35,40 - - - - - - 27,27 - - - 26,55 26,55 - 0,89 0,88 0,91 0,45 0,44 0,45 0,36 0,35 0,36 0,09 0,09 0,09 7,08 - - - 7,08 7,27 - - - - - - - - - - - - - - - - 2,68 - - - 2,65 - 90 120 180 Gut Gut Gut Schlecht Schlecht Schlecht [Fortsetzung Tabelle 2] Vergleichsbeispiel 5 Vergleichsbeispiel 6 Vergleichsbeispiel 7 Vergleichsbeispiel 8 25 26 27 28 42,86 - - - 63,64 55,52 57,14 - - - - - - 27,27 87,38 23,79 - - - - - - 0,88 0,91 0,86 0,44 0,45 0,43 0,35 0,36 0,34 0,09 0,09 0,09 - - - 7,08 7,27 9,71 8,62 - - 2,65 - 2,91 10,34 - - - - - - - - - - 2,65 100 60 170 35 Gut Schlecht Schlecht Gut Schlecht Schlecht Schlecht Schlecht The results obtained are shown in Table 2.

[Table 2 continued] Example 1 Example 2 Example 3 1 2 3 - 26.55 - 61.95 - 63.64 - 35.40 - - - - 26.55 26.55 27.27 - - - - - - 0.88 0.88 0.91 0.44 0.44 0.45 0.35 0.35 0.36 0.09 0.09 0.09 - - - 7.08 7.08 7.27 2.65 2.65 2.65 - - - - - - - - 130 130 90 Good Good Good Good Good Good [Table 2 continued] Example 4 Example 5 Example 6 4 5 6 - - - 63.64 62.78 61.95 - - - - - - 27.27 26.91 26.55 - - - - - - 0.91 0.90 0.88 0.45 0.45 0.44 0.36 0.36 0.35 0.09 0.09 0.09 - - - 6.36 6.73 7.08 - - - 0.91 1.79 2.65 - - - - - - - - - - - - - - - 150 140 125 Good Good Good Good Good Good [Table 2 continued] Example 7 Example 8 Example 9 7 8th 9 - - 26.55 60.34 44.25 - - - 35.40 - - - 25.86 44.25 26.55 - - - - - - 0.86 0.88 0.88 0.43 0.44 0.44 0.34 0.35 0.35 0.09 0.09 0.09 - - - 7.76 7.08 7.08 - - - 4:31 2.65 2.65 - - - - - - - - - - - - - - - 80 155 140 Good Good Good Good Good Good [Table 2 continued] Example 10 Example 11 Example 12 10 11 12 29:13 21.51 26.79 - - - 38.83 53.76 35.71 - - - 19:42 10.75 26.79 - - - - - - 0.97 1.08 0.45 0.49 0.54 7.37 0.39 0.43 0.18 0.10 0.11 0.04 - - - 7.77 8.60 - - - - 2.91 3.23 2.68 - - - - - - - - - - - - - - - 125 110 150 Good Good Good Good Good Good [Table 2 continued] Example 13 Example 14 Example 15 13 14 15 26.79 27.03 - - - - 35.71 36.04 35.40 - - 26.55 26.79 27.03 26.55 - - - - - - - 1.80 0.88 - 0.90 0.44 - 0.72 0.35 - 0.18 0.09 - - - 8.04 5.86 7.08 - - - 2.68 0.45 2.65 - - - - - - - - - - - - - - - 200 130 100 Good Good Good Good Good Good [Table 2 continued] Example 16 Example 17 Example 18 16 17 18 26.55 26.55 26.55 - - - 35.40 35.40 35.40 - - - - - 26.55 26.55 - - - 26.55 - 0.88 0.88 0.88 0.44 0.44 0.44 0.35 0.35 0.35 0.09 0.09 0.09 - - - 7.08 7.08 7.08 2.68 - - 2.65 2.65 2.65 - - - - - - - - - - 80 100 125 Good Good Good Good Good Good [Table 2 continued] Example 19 Example 20 Example 21 19 20 21 - 26.55 - 61.95 - 61.95 - 35.40 - - - - 26.55 26.55 26.55 - - - - - - 0.88 0.88 0.88 0.44 0.44 0.44 0.35 0.35 0.35 0.09 0.09 0.09 - - - 7.08 7.08 7.08 - - - - 2.65 - - 2.65 - - 2.65 - - - - 130 140 100 Good Good Good Good Good Good [Table 2 continued] Comparative example 1 Comparative example 2 Comparative example 3 22 23 24 26.55 26.55 - - - 63.64 35.40 35.40 - - - - - - 27.27 - - - 26.55 26.55 - 0.89 0.88 0.91 0.45 0.44 0.45 0.36 0.35 0.36 0.09 0.09 0.09 7.08 - - - 7.08 7.27 - - - - - - - - - - - - - - - - 2.68 - - - 2.65 - 90 120 180 Good Good Good Bad Bad Bad [Table 2 continued] Comparative example 5 Comparative example 6 Comparative example 7 Comparative example 8 25 26 27 28 42.86 - - - 63.64 55.52 57.14 - - - - - - 27.27 87.38 23.79 - - - - - - 0.88 0.91 0.86 0.44 0.45 0.43 0.35 0.36 0.34 0.09 0.09 0.09 - - - 7.08 7.27 9.71 8.62 - - 2.65 - 2.91 10.34 - - - - - - - - - - 2.65 100 60 170 35 Good Bad Bad Good Bad Bad Bad Bad

In Table 2, from the viewpoint of heat resistance, those with a peeling area ratio of less than 20% after the cold/heat cycle test were rated “good” and those with a peeling area ratio of more than 20% were rated “poor”. A 5×5 mm Si chip was used for peel test 1, and a 7×7 mm Si chip was used for peel test 2. A sputtered silver coating is provided on the back of the two chips.

It is clear from the results in Table 2 that when 5×5 mm silicon chips are used, the peeling area is small and good results are obtained even in comparative examples, while when 7×7 mm silicon chips are used, the peel strength is excellent in all Comparative Examples 1 to 3, 5 and 8, which showed good results using 5×5 mm silicon chips. In contrast, with regard to the sintered parts (Examples 1 to 21) obtained according to the present invention, it is clear that even when using 7×7 mm silicon chips, the peeling area after the cold/heat cycle test of 2000 cycles is small and a highly reliable joined part is obtained becomes.

30C/

200°C 200°C 200°C 200°C 200°C 250°C 250°C 250°C 250°C 250°C 50ppm 50ppm 50ppm 50ppm 50ppm 90,2 63,9 83,8 81,1 80,4 87,6 73,7 90,3 79,9 85 1,9 28,3 9,3 11,5 12,4 3,8 18,3 2,5 9,6 6,2 7,9 7,8 6,9 7,4 7,2 8,6 8 7,2 10,5 8,8 9 6 10 3 2 [Fortsetzung Tabelle 3] Ausführungsbeispiel 39 Ausführungsbeispiel 40 8 8 7x7mm 7x7mm Au Au Cu Cu 3% 3% 5µm 5µm Silber Silber 7°C/

10°C/

200°C 200°C 250°C 250°C 50ppm 50ppm 81,2 81,2 88,3 88,7 10,5 9,8 2,8 2,5 8,3 9 8,9 8,8 3 5 [Tabelle 4] 0 Vergleichsbeispiel 9 Probenummer 24 Chipgröße 7x7mm Edelmetallart der Chipfügefläche Ag Edelmetallart der Oberfläche von Kupfersubstrat Ag (Harzpartikelmenge in elektrisch leitfähiger Zusammensetzung nach Sintern) 0% Mittlerer Harzpartikeldurchmesser in Sinterteil 5µm Elektrisch leitfähige Füllstoffe Silber Aufheizgeschwindigkeit 5°C/Min. Vorbrenntemperatur (60min) 200°C Sintertemperatur (60min) 250°C Sauerstoffkonzentration 50ppm Metallfläche Linkes Ende Flächen% 96 Mitte Flächen% 87,8 Harzpartikelfläche Linkes Ende Flächen% 0 Mitte Flächen% 0 Sonstige Fläche Linkes Ende Flächen% 4 Mitte Flächen% 12,2 Zuverlässigkeitsprüfung (-50°C⇔150°C) Nachherige Ablösungsfläche 2000-Zyklen Flächen% 95
* Sonstige Fläche: Rückstand aus Zwischenspalt + Bindemittelharz usw.The electrically conductive composition was then applied to a copper substrate whose surface was coated with a noble metal, e.g. B. Au, Pd or Ag, coated, and applied to a copper substrate whose surface is not coated, and on these applied surfaces was then a chip (2 × 2 mm or 7 × 7 mm), the joining surface with a noble metal is coated, placed and sintered. The Coating of the substrate and the chip with noble metal was carried out by means well known to those skilled in the art, such as plating, sputtering, metallization, etc. The size of the chips placed in exemplary embodiments 22 to 26 is 2 × 2 mm, and the size of those in exemplary embodiments 27 to 40 (Table 3) and Comparative Examples 9 to 12 (Table 4) placed chips is 7 × 7 mm. In Reference Examples 1 to 5, sintering was performed without laying chips. The heating rate during sintering is 3 to 7 °C/min. In Working Examples 22 and 27, the sintered part was prepared by raising the temperature to 250°C at the above heating rate without pre-firing. The sectional area of the obtained sintered compact was observed with the SEM, and the proportion of electroconductive fillers (metal area in Tables 3 and 4) based on the total sectional area of the sintered compact and the proportion of resin particles (resin particle area in Tables 3 and 4) were calculated. The electrically conductive composition used, the chip size, the sintering conditions, the metal content and the resin particle content based on the cut surface of the sintered part, the joint strength and the results of the reliability tests (cold/heat cycle test) are summarized in Tables 3 and 4. [Table 3] Example 22 Example 23 sample number 8th 8th chip size 2x2mm 2x2mm Noble metal type of chip bonding area Ouch Ouch Precious metal species of the surface of copper substrate Cu Cu (Amount of resin particles in electroconductive composition after sintering) 3% 3% Mean resin particle diameter in sintered part 5µm 5µm Electrically conductive fillers Silver Silver heating rate 5°C/min 5°C/min Pre-firing temperature (60min) Without 50°C Sintering temperature (60min) 250°C 250°C oxygen concentration 50ppm 50ppm metal surface left end area % 75.4 76.6 center area % 78.7 74.3 resin particle surface left end area % 12.4 10 center area % 8.7 12.8 other area left end area % 12.2 13.4 center area % 12.6 12.9 Reliability test (-50°C⇔150°C) Post separation surface 2000 cycles area % <1 <1 [Table 3 continued] Example 24 Example 25 Example 26 Example 27 Example 28 8th 8th 8th 8th 8th 2×2mm 2×2mm 2×2mm 7×7mm 7×7mm Ouch Ouch Ouch Ouch Ouch Cu Cu Cu Cu Cu 3% 3% 3% 3% 3% 5µm 5µm 5µm 5µm 5µm Silver Silver Silver Silver Silver 5°C/min 5°C/min 5°C/min 5°C/min 5°C/min 100°C 150°C 200°C Without 50°C 250°C 250°C 250°C 250°C 250°C 50ppm 50ppm 50ppm 50ppm 50ppm 72.7 76.2 79.8 80.2 75.9 78.5 78 80.3 70.7 74.4 12.2 13.6 11 7 9.8 8.5 9.9 9.1 6.8 8.4 15.1 10.2 9.2 12.8 14.3 13 12.1 10.6 22.5 17.2 <1 <1 <1 4 2 [Table 3 continued] Example 29 Example 30 Example 31 Example 32 Example 33 8th 8th 8th 8th 8th 7x7mm 7x7mm 7x7mm 7x7mm 7x7mm Ouch Ouch Ouch Ouch Ag Cu Cu Cu Au/Pd Ag 3% 3% 3% 3% 3% 5µm 5µm 5µm 5µm 5µm Silver Silver Silver Silver Silver 5°C/min 5°C/min 5°C/min 5°C/min 5°C/min 100°C 150°C 200°C 200°C 200°C 250°C 250°C 250°C 250°C 250°C 50ppm 50ppm 50ppm 500ppm 21% 80.7 77.8 80.4 79.8 80.8 73.1 69.7 89.9 87.1 88.6 8.4 12.5 12.8 12.5 11.9 7.5 9.2 3 4.2 3.2 10.9 9.7 6.8 7.7 7.3 19.4 21:1 7.1 8.7 8.2 3 3 2 2 1 [Table 3 continued] Example 34 Working example 35 Example 36 Example 37 Example 38 4 7 15 8th 8th 7x7mm 7x7mm 7x7mm 7x7mm 7x7mm Ag Ag Ag Ouch Ouch Ag Ag Ag Cu Cu 1% 5% 3% 3% 3% 5µm 5µm 5µm 5µm 5µm Silver Silver 57% by mass silver + 43% by mass copper Silver Silver 5°C/min 5°C/min 5°C/min 1°C/

30C/

200°C 200°C 200°C 200°C 200°C 250°C 250°C 250°C 250°C 250°C 50ppm 50ppm 50ppm 50ppm 50ppm 90.2 63.9 83.8 81.1 80.4 87.6 73.7 90.3 79.9 85 1.9 28.3 9.3 11.5 12.4 3.8 18.3 2.5 9.6 6.2 7.9 7.8 6.9 7.4 7.2 8.6 8th 7.2 10.5 8.8 9 6 10 3 2 [Table 3 continued] Example 39 Example 40 8th 8th 7x7mm 7x7mm Ouch Ouch Cu Cu 3% 3% 5µm 5µm Silver Silver 7°C/

10°C/

200°C 200°C 250°C 250°C 50ppm 50ppm 81.2 81.2 88.3 88.7 10.5 9.8 2.8 2.5 8.3 9 8.9 8.8 3 5 [Table 4] 0 Comparative example 9 sample number 24 chip size 7x7mm Noble metal type of chip bonding area Ag Precious metal species of the surface of copper substrate Ag (Amount of resin particles in electroconductive composition after sintering) 0% Mean resin particle diameter in sintered part 5µm Electrically conductive fillers Silver heating rate 5°C/min Pre-firing temperature (60min) 200°C Sintering temperature (60min) 250°C oxygen concentration 50ppm metal surface left end Area% 96 center Area% 87.8 resin particle surface left end Area% 0 center Area% 0 other area left end Area% 4 center Area% 12.2 Reliability test (-50°C⇔150°C) Post separation surface 2000 cycles Area% 95
* Other area: residue from intermediate gap + binder resin etc.

Table 3 shows exemplary embodiments in which the substrate and chip are joined according to the invention using the electrically conductive compositions with sample numbers 4, 7, 8 and 15 listed in Table 2. Also in the table are the percentage distributions of the metal area (electrically conductive fillers), the resin particle area (resin particles (C)) and the other area (interstitial gaps and residues of binder resin, etc.) at the left end part and middle part of the cut surface of the by the method of the present invention received sintered part listed. It is shown that the smaller the difference between the left end part and the middle part, the more uniformly the electrically conductive fillers and the resin particles are distributed in the sintered part. When the chip size is 2×2mm (Embodiments 22 to 26), the difference between the left end part and the middle part is small and the peeling area in the reliability test is also very small, while in laying and sintering of 7×7mm chips (Embodiments 27 to 40) the difference between the left end part and the middle part is slightly larger, but the peeling area is small in the reliability test, hence it can be seen that a highly reliable joint is still achieved. On the other hand, Table 4 shows a sintered part obtained using the same electrically conductive composition as in Comparative Examples 3 and 8 shown in Table 2 (Sample Nos. 24 and 28), a sintered part obtained using the same electrically conductive composition according to the present invention (Sample No. 8) and sintered under different sintering conditions than the present invention, and Reference Examples 1 to 5 sintered without laying a chip. In Comparative Example 9 obtained using an electroconductive composition without resin particles (C) (Sample No. 24), the peeling area after the cold/heat cycle is 95%, and in Comparative Example 10 obtained using Sample No. 28, which is more than 10 % contains resin particles (C), the peeling area is 45%, while the peeling area of the sintered compact obtained by the present invention is 10% or less, respectively. Even with the electroconductive composition of the present invention, in Comparative Examples 11 and 12 in which sintering was performed at a heating rate exceeding a predetermined range or without controlling the heating rate, the peeling area after the cold/heat cycle is very large. From these results, it is clear that a highly reliable joined part can be obtained by the present invention even with a large chip area. In Reference Examples 1 to 5, the substrate was coated with the electroconductive composition of the present invention and then sintered without placing a chip thereon. In these reference examples, the imbalance in the distribution of the resin particles (C) at the left end part and the middle part of the cut surface of the sintered compact (difference between the area % at the left end and the area % at the middle part) is small, from which it can be seen that the resin particles (C) are evenly distributed throughout the sintered part. It is preferable that the resin particles (C) are uniformly distributed from the viewpoint of stress relaxation and distribution in the sintered compact and the bonded compact, respectively. In comparison with the comparative examples, it is clear that in the working examples 22 to 40 according to the present invention, like the reference examples, the imbalance in the distribution of the resin particles (C) is small and a highly reliable bonded member is obtained.

11 FIG. 12 shows electron micrographs showing cut surfaces of the electrically conductive composition after they have been applied to a 7×7 mm component (Si chip) and sintered. It is clear from the sectional views of Working Example 3 and Working Example 8 that, in the electroconductive composition of the present invention, the resin particles are uniformly distributed in the electroconductive composition after sintering and substantially retain their original shape as shown in FIG 3 shown. The resin particles are thus uniformly distributed in the electrically conductive composition after sintering, whereby stress is reduced and distributed according to the present invention, and a highly reliable joined part is obtained. On the other hand, from Comparative Example 6, it can be seen that the resin particles are melted and deformed and distributed in an uneven shape as in FIG 2 shown.

12 shows an example of the propagation of cracks in an adherend obtained with the electrically conductive composition according to the invention. By using the electroconductive composition of the present invention, sintering is performed under conditions where the rate of change of the maximum Feret diameter of the resin particles before and after sintering is less than 1.20, thereby allowing the resin particles to substantially retain their original shape even after sintering . Therefore, cracks occurring in the cold/heat cycle do not occur at the interface of the adherend, but are only fine cracks occurring along the resin particles in the adherend. This distributes the stresses and minimizes the cracks caused by cold/heat cycles, which leads to the avoidance of major delaminations at the interfaces between the component and the adherend.

In the above, the present invention was explained in detail based on specific aspects, however, it is apparent for those skilled in the art that various changes and modifications can be made without departing from the technical spirit and scope of the present invention.

[Industrial Applicability]

According to the present invention, an electrically conductive composition containing electrically conductive fillers applied to components, particularly components used in the field of electronics, e.g. B. Electronic parts, concretely applied to electronic parts for mounting in vehicles or communication devices, and can form an adherend that shows good thermal conductivity after sintering and little prone to peeling and cracks in relatively large even with repeated significant temperature changes components or joined parts and is highly reliable, as well as a Method for joining a component using the electrically conductive composition and a method for producing an electrically conductive sintered part or joined part.

Reference List

1

component

2

electrically conductive composition

3

resin particles

4

cavity

10

minimum feret diameter

11

short axis

14

maximum feret diameter

15

long axis

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• JP 2015162392 [0006]
• JP201665146 [0006]
• JP 2014194013 [0006]
• WO 2016063931 [0006, 0075]
• WO 2019013230 [0006]
• WO 2019013231 [0006]
• WO 2020145170 [0006]

Claims (20)

An electroconductive composition containing electroconductive fillers and resin particles, wherein the rate of change of the maximum Feret diameter of the resin particles before and after sintering the electroconductive composition is less than 1.20. Electrically conductive composition according to claim 1 , where the rate of change of the maximum Feret diameter ranges from 0.9 to 1.1. Electrically conductive composition according to claim 1 or 2 , wherein the temperature at which the electrically conductive composition is sintered is in the range of 80°C to 300°C. Electrically conductive composition according to any one of Claims 1 until 3 containing (A) silver microparticles having an average particle diameter of 10 to 300 nm as the electroconductive fillers. Electrically conductive composition according to claim 4 containing (B) metal particles having an average particle diameter of 0.5 to 10 µm as the electrically conductive fillers. Electrically conductive composition according to claim 5 containing (C) resin particles having an average particle diameter of 2 to 15 µm as the resin particles. Electrically conductive composition according to claim 6 wherein the resin constituting the resin particles (C) is selected from the group consisting of a thermoplastic resin, a thermosetting resin and a silicone resin. Electrically conductive composition according to claim 7 , wherein the thermoplastic resin is selected from the group of polyolefins and polyamides. Electrically conductive composition according to any one of Claims 6 until 8th , wherein the average particle diameter of the resin particles (C) corresponds to 1 to 85% of the thickness of a sintered compact or bonded compact obtained after sintering the electrically conductive composition. Electrically conductive composition according to any one of Claims 6 until 9 wherein the electroconductive composition contains the silver microparticles (A) at 5 to 50% by mass, the metal particles (B) at 35 to 85% by mass and the resin particles (C) at 0.1 to 10% by mass by mass contains the electrically conductive composition. Electrically conductive composition according to any one of Claims 1 until 10 wherein the electroconductive composition further contains (D) a binder resin at 0.5 to 10% by mass based on the mass of the electroconductive composition. Electrically conductive composition according to any one of Claims 5 until 11 wherein the ratio of the silver microparticles (A) to the metal particles (B) in the electroconductive composition is in the range of 5:95 to 60:40 by mass. Electrically conductive composition according to any one of Claims 1 until 12 which further contains at least one component selected from the group consisting of a curing agent, a curing accelerator, a solvent, an antioxidant, a UV absorber, a tackifier, a viscosity adjuster, a dispersant, an adhesion promoter, a toughener and an elastomer . Method for joining components using an electrically conductive composition according to one of Claims 1 until 13 comprising a step of sintering the electroconductive composition so that the rate of change of the maximum Feret diameter of the resin particles after sintering relative to the maximum Feret diameter of the resin particles before sintering is less than 1.20. Process for the production of an electrically conductive sintered part or an electrically conductive bonded part using an electrically conductive composition according to one of Claims 1 until 13 , comprising a step of sintering the electrically conductive composition so that the rate of change of the maximum Feret diameter of the resin particles after sintering relative to the maximum Feret diameter of the resin particles before sintering is less than 1.20. procedure after Claim 14 or 15 , wherein the temperature at which the electrically conductive composition is sintered is in the range of 80°C to 300°C. Procedure according to one of Claims 14 until 16 , wherein the heating rate when sintering the electrically conductive composition is 1 to 10 °C/min. Use of the electrically conductive composition according to any one of Claims 1 until 13 to form an assembly part of components, an electrically conductive layer or a circuit. Sintered part or joined part containing electrically conductive fillers and resin particles, wherein the sintered part or the joined part by sintering the electrically conductive composition according to one of Claims 1 until 13 is obtained, the proportion of the electrically conductive fillers being 60 to 95% by area based on the cut surface of the sintered part or joining part, the proportion of the resin particles being 1 to 35% by area, the proportion of the components other than the resin particles and the electrically conductive fillers and the intermediate gaps is 4 to 25% by area, and the average particle diameter of the resin particles is 2 to 15 µm. Component with a sintered part or joining part claim 19 .

Images