EP3867005A1 - Lead-free solder alloy and use of such an alloy - Google Patents

Lead-free solder alloy and use of such an alloy

Info

Publication number
EP3867005A1
EP3867005A1 EP19797182.3A EP19797182A EP3867005A1 EP 3867005 A1 EP3867005 A1 EP 3867005A1 EP 19797182 A EP19797182 A EP 19797182A EP 3867005 A1 EP3867005 A1 EP 3867005A1
Authority
EP
European Patent Office
Prior art keywords
weight
alloy
copper
tin
antimony
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP19797182.3A
Other languages
German (de)
French (fr)
Inventor
Anne Marie LAUGT
Aurélie DUCOLOMBIER
Marc WARY
Raphaël PESCI
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
DEHON
Original Assignee
Dehon Sas
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dehon Sas filed Critical Dehon Sas
Publication of EP3867005A1 publication Critical patent/EP3867005A1/en
Pending legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/24—Selection of soldering or welding materials proper
    • B23K35/26—Selection of soldering or welding materials proper with the principal constituent melting at less than 400 degrees C
    • B23K35/262—Sn as the principal constituent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/24—Selection of soldering or welding materials proper
    • B23K35/26—Selection of soldering or welding materials proper with the principal constituent melting at less than 400 degrees C
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C13/00—Alloys based on tin
    • C22C13/02—Alloys based on tin with antimony or bismuth as the next major constituent

Definitions

  • the present invention relates to a solder alloy composition which is free of lead.
  • solder alloy comprising lead which has a high melting point of approximately 300 ° C. Due to regulatory constraints, such lead-based alloys can no longer be used.
  • a tin-silver-copper alloy is better known by its English abbreviation "SAC alloy”.
  • SAC alloy an SAC305 alloy is known, comprising approximately 3% by mass of silver and approximately 0.5% by mass of copper, the melting temperature of which is between 217 ° C. and 220 ° C.
  • Such an SAC305 alloy has lower performance than a lead alloy for operating temperatures above 150 ° C. However, such operating temperatures are frequently reached in the petroleum, aeronautical, automotive or other fields. In addition, such an SAC305 alloy is not very robust to thermal shocks between -40 ° C and + 150 ° C. We are therefore looking for an alloy that does not melt below 200 ° C or ideally 230 ° C and is as reliable in terms of thermal cycling, electrical and thermal conductivity and mechanical resistance as the leaded alloy.
  • An object of the invention is therefore to provide a brazing alloy with good reliability for use in a variety of welding processes, such as wave soldering, reflow soldering, dip soldering, wire brazing and selective soldering. .
  • the invention relates to a lead-free solder alloy having a composition comprising:
  • Cu copper
  • the alloy comprises:
  • the alloy comprises:
  • such a brazing alloy has melting temperatures and phase diagrams which are optimal for implementing a reflow process.
  • a conventional SAC alloy i.e. a Tin-Silver-Copper alloy
  • the mechanical resistance is increased by more than 50%
  • the wetting performance is increased and the thermal conductivity is increased.
  • the cost of an alloy according to the invention is reduced significantly, preferably by around 50%.
  • the thermal conductivity greater than 60W.nr 1 .K 1 , preferably between 60W.nr 1 K 1 and 65W.nr 1 K 1 .
  • the wettability is less than 25 °.
  • the alloy comprises only tin (Sn), antimony (Sb) and copper (Cu).
  • the alloy comprises:
  • the alloy comprises 90% -92% by weight of tin (Sn).
  • the alloy comprises 7% -8% by weight of antimony (Sb).
  • the alloy comprises 1% -2% by weight of copper (Cu).
  • the alloy comprising:
  • the alloy comprising:
  • the invention also relates to a composite alloy for brazing comprising a brazing alloy as presented above and 5% -25% by weight of silver or copper particles.
  • the composite alloy for brazing consists only of an alloy of brazing and particles of silver or copper.
  • Such a composite alloy of solder improves the thermal and electrical conductivity.
  • the silver or copper particles have dimensions between 1 and 30 micrometers.
  • the invention also relates to the use of an alloy as presented above for a process for remelting electronic components.
  • the invention also relates to the use of an alloy as presented above for soldering a housing of electronic components and / or a surface mounting device (SMD) to a substrate, the alloy being applied in the form of a paste.
  • SMD surface mounting device
  • a brazing alloy is proposed for wave soldering, for selective soldering and in particular for a method of soldering electronic components by reflow.
  • Such an alloy can also be used for the manufacture or connection of electronic components, in particular, semiconductors.
  • a lead-free solder alloy having a composition comprising:
  • a melting range between 220 ° C. and 340 ° C. is obtained.
  • the alloy comprises: - 88% -94% by weight of tin (Sn),
  • the alloy comprises:
  • Such a brazing alloy has a melting point which is between 220 ° C and 310 ° C and has very good properties in the mechanical, electrical and wetting fields. In addition, the absence of lead makes it possible to comply with the new environmental standards.
  • the alloy comprises:
  • a melting range between 220 ° C. and 300 ° C. is obtained.
  • the alloy comprises:
  • the alloy consists of:
  • a melting range between 220 ° C. and 250 ° C. is obtained.
  • the alloy consists of:
  • the alloy comprises:
  • the alloy comprises:
  • Such a brazing alloy has melting temperatures and phase diagrams which are optimal for implementing a reflow process.
  • a conventional SAC alloy i.e. a Tin-Silver-Copper alloy
  • the mechanical resistance is increased by more than 50%
  • the wetting performance is increased and the thermal conductivity is increased.
  • the cost of an alloy according to the invention is reduced significantly, preferably on the order of 50%.
  • the alloy according to the invention was produced in quartz tubes closed under vacuum to avoid the phenomenon of oxidation, then in alumina crucibles. Elements of high purity, Sn (99.949%), Sb (99.76%) and Cu (99.99%) were introduced and mixed after weighing in the crucibles, then placed in a resistance oven at a temperature of 370 ° C.
  • XRF X-ray fluorescence
  • EDS dispersive dispersion spectrometry
  • SEM scanning electron microscope
  • the high energy X-ray diffraction ring method was also used at the European Synchrotron Radiation Facility (ESRF) in Grenoble.
  • ESRF European Synchrotron Radiation Facility
  • the DSC analyzes then made it possible to determine the solidus and liquidus temperatures as well as the enthalpy of fusion from samples with a mass of approximately 50 mg in 30 ⁇ l cylindrical aluminum crucibles.
  • the test cycle includes two heating and cooling periods between 20 ° C and 350 ° C with a speed of 5 ° C / min.
  • the alloy has good resistance to thermal shock between -40 ° C and + 150 ° C.
  • the wettability measurements were carried out with a wetting balance. To implement this method, a rectangular plate of a substrate is immersed in the molten solder having a defined depth and the force is measured during the test.
  • the procedure for preparing each sample before the test consists of cleaning / degreasing with acetone followed by a chemical attack with a 2% aqueous solution of nitric acid, rinsing with distilled water and d '' immersion in a flow of CA (activated rosin) (ECOFREC TM CMA 185 from Inventec).
  • the ability of a liquid to spread over a surface is characterized by the angle between the surface of the substrate and a droplet deposited on the surface. The smaller the angle, the better the wettability. If the wettability is greater than 90 °, the wettability is zero. According to the invention, the wetting angle is closed at 20 ° in our case (between 25 ° and 35 ° for the SAC305).
  • the alloy was prepared in the form of cylindrical test pieces for the tensile tests (according to ISO 6892) which were directly cast in a stainless steel mold.
  • the thermal conductivity was measured by the hot disc method.
  • a spiral nickel sensor is placed between two cylindrical samples of the alloy to be measured. These samples, 10 mm high and 35 mm in diameter, must have a flat face to improve contact with the sensor. This sensor fulfills a first heating function and a second measurement function. For this type of measurement, the sample size is directly linked to the expected conductivity of the sample.
  • the tensile tests were carried out with a tensile testing machine equipped with a load sensor of 5 kN and a strain gauge of 25 mm, with a strain rate of 3.10-2 s-1 (0.75 mm / min).
  • the mechanical properties were determined by three tensile tests at microhardness at room temperature.
  • the microhardness was measured with a Vickers indenter under a load of 10 N for 10 seconds.
  • the average value is around 23HV instead of 6HV and 18HV for Tin and SAC 05, respectively.
  • the mechanical behavior is similar to that of SAC305, without hardening.
  • the maximum elongation is less than 35%, preferably of the order of 34%, the maximum elongation being of the order of 38% for a conventional SAC alloy.
  • the mechanical strength of the alloy according to the invention is greater than 60 MPa, preferably of the order of 70 MPa, which is greater than that of a conventional SAC alloy which is of the order of 50 MPa.
  • the thermal conductivity l which is one of the predominant parameters of a soldering alloy in microelectronics, since it guarantees good dissipation of the heat induced by the current, has been determined by the heating disc method.
  • the thermal conductivity greater than BOW.m- i .K 1 , preferably between 60W. m- l .K 1 and 65W. m- i .K 1 .
  • An average value of 63.60 W. m- i .K 1 with a standard deviation of 0.05 W. m- i .K 1 was obtained by three measurements carried out on the same sample.
  • the alloy can be used in wave soldering, selective soldering, dip soldering, as part of wire, for placement of CMS and for applications dough-in-dough.
  • the alloy is packaged in the form of bars, preforms, ingots, powder, solder paste or solder cream.
  • the alloy according to the invention with silver or copper particles having a dimension between 1 and 30 micrometers in order to form a composite alloy.
  • silver or copper particles are added in an amount of 5 to 25% by weight of the mixture.

Abstract

The invention relates to a lead-free solder alloy having a composition comprising: - 86% - 94% by weight of tin (Sn), - 5% - 10% by weight of antimony (Sb) and - 0.5% - 4% by weight of copper (Cu).

Description

ALLIAGE DE BRASURE SANS PLOMB ET UTILISATION D’UN TEL ALLIAGE  LEAD-FREE SOLDER ALLOY AND USE OF SUCH AN ALLOY
DOMAINE TECHNIQUE GENERAL ET ART ANTERIEUR GENERAL TECHNICAL AREA AND PRIOR ART
La présente invention concerne une composition d’alliage de brasure qui soit dépourvu de plomb. The present invention relates to a solder alloy composition which is free of lead.
De manière connue, pour fabriquer ou connecter des composants électroniques entre eux ou à une carte électronique, il est connu d’utiliser un alliage de brasure comportant du plomb qui a un haut point de fusion d'environ 300°C. Du fait de contraintes réglementaires, de tels alliages à base de plomb ne peuvent plus être utilisés. Afin de remplacer ces alliages, on connaît un alliage Etain-Argent-Cuivre plus connu sous son abréviation anglaise « alliage SAC ». On connaît en particulier un alliage SAC305, comprenant environ 3% en masse d’argent et environ 0,5% en masse de Cuivre, dont la température de fusion est comprise entre 217°C et 220°C. In known manner, to manufacture or connect electronic components to each other or to an electronic card, it is known to use a solder alloy comprising lead which has a high melting point of approximately 300 ° C. Due to regulatory constraints, such lead-based alloys can no longer be used. In order to replace these alloys, a tin-silver-copper alloy is better known by its English abbreviation "SAC alloy". In particular, an SAC305 alloy is known, comprising approximately 3% by mass of silver and approximately 0.5% by mass of copper, the melting temperature of which is between 217 ° C. and 220 ° C.
Un tel alliage SAC305 possède des performances inférieures à un alliage plombé pour des températures d’utilisation supérieures à 150°C. Or, de telles températures d’utilisation sont atteintes de manière fréquente dans le domaine pétrolier, aéronautique, automobile ou autre. De plus, un tel alliage SAC305 est peu robuste aux chocs thermiques entre -40°C et +150°C. On recherche donc un alliage ne refondant pas en-dessous de 200°C ou idéalement de 230°C et aussi fiable en termes de cyclages thermiques, de conductivité électrique et thermique et de résistance mécanique que l’alliage plombé. Such an SAC305 alloy has lower performance than a lead alloy for operating temperatures above 150 ° C. However, such operating temperatures are frequently reached in the petroleum, aeronautical, automotive or other fields. In addition, such an SAC305 alloy is not very robust to thermal shocks between -40 ° C and + 150 ° C. We are therefore looking for an alloy that does not melt below 200 ° C or ideally 230 ° C and is as reliable in terms of thermal cycling, electrical and thermal conductivity and mechanical resistance as the leaded alloy.
Un but de l'invention est donc de fournir un alliage de brasure avec une bonne fiabilité pour une utilisation dans une variété de procédés de soudage, tels que brasage à la vague, brasage par refusion, brasage au trempé, brasage de fil et brasage sélectif. An object of the invention is therefore to provide a brazing alloy with good reliability for use in a variety of welding processes, such as wave soldering, reflow soldering, dip soldering, wire brazing and selective soldering. .
PRESENTATION GENERALE DE L’INVENTION GENERAL PRESENTATION OF THE INVENTION
A cet effet, l’invention concerne un alliage de brasure sans plomb ayant une composition comprenant : To this end, the invention relates to a lead-free solder alloy having a composition comprising:
86%-94% en poids d’étain (Sn),  86% -94% by weight of tin (Sn),
5%-10% en poids d'antimoine (Sb) et  5% -10% by weight of antimony (Sb) and
0,5%-4% en poids de cuivre (Cu), de préférence, entre 1 % et 4%.  0.5% -4% by weight of copper (Cu), preferably between 1% and 4%.
De manière préférée, l’alliage comprend : Preferably, the alloy comprises:
88%-94% en poids d’étain (Sn), 6%-9% en poids d'antimoine (Sb) et 88% -94% by weight of tin (Sn), 6% -9% by weight of antimony (Sb) and
0,5%-2,5% en poids de cuivre (Cu).  0.5% -2.5% by weight of copper (Cu).
De préférence encore, l’alliage comprend : More preferably, the alloy comprises:
- 88%-93% en poids d’étain (Sn),  - 88% -93% by weight of tin (Sn),
- 6%-9% en poids d'antimoine (Sb) et  - 6% -9% by weight of antimony (Sb) and
1 %-3% en poids de cuivre (Cu).  1% -3% by weight of copper (Cu).
De manière avantageuse, un tel alliage de brasure possède des températures de fusion et des diagrammes de phase qui sont optimaux pour mettre en oeuvre un procédé de refusion. Par comparaison à un alliage SAC classique, c’est-à-dire un alliage Etain-Argent-Cuivre, la résistance mécanique est augmentée de plus de 50%, les performances de mouillage sont augmentées et la conductivité thermique est augmentée. De manière avantageuse, le coût d’un alliage selon l’invention est réduit de manière importante, de préférence, de l’ordre de 50%. De manière préférée, la conductivité thermique supérieure à 60W.nr1.K 1, de préférence, comprise entre 60W.nr1 K 1 et 65W.nr1 K 1 . De préférence, la mouillabilité est inférieure à 25°. Advantageously, such a brazing alloy has melting temperatures and phase diagrams which are optimal for implementing a reflow process. Compared to a conventional SAC alloy, i.e. a Tin-Silver-Copper alloy, the mechanical resistance is increased by more than 50%, the wetting performance is increased and the thermal conductivity is increased. Advantageously, the cost of an alloy according to the invention is reduced significantly, preferably by around 50%. Preferably, the thermal conductivity greater than 60W.nr 1 .K 1 , preferably between 60W.nr 1 K 1 and 65W.nr 1 K 1 . Preferably, the wettability is less than 25 °.
De manière préférée, l’alliage comprend uniquement de l’étain (Sn), de l’antimoine (Sb) et du cuivre (Cu). Preferably, the alloy comprises only tin (Sn), antimony (Sb) and copper (Cu).
De manière préférée, l’alliage comprend : Preferably, the alloy comprises:
90%-92% en poids d’étain (Sn),  90% -92% by weight of tin (Sn),
7%-8% en poids d'antimoine (Sb) et  7% -8% by weight of antimony (Sb) and
1 %-2% en poids de cuivre (Cu).  1% -2% by weight of copper (Cu).
Selon un aspect de l’invention, l’alliage comprend 90%-92% en poids d’étain (Sn). According to one aspect of the invention, the alloy comprises 90% -92% by weight of tin (Sn).
Selon un autre aspect de l’invention, l’alliage comprend 7%-8% en poids d'antimoine (Sb). According to another aspect of the invention, the alloy comprises 7% -8% by weight of antimony (Sb).
Selon un autre aspect de l’invention, l’alliage comprend 1 %-2% en poids de cuivre (Cu). According to another aspect of the invention, the alloy comprises 1% -2% by weight of copper (Cu).
De manière préférée, l’alliage comprenant : Preferably, the alloy comprising:
90,6%-91 ,4% en poids d’étain (Sn),  90.6% -91.4% by weight of tin (Sn),
7,3%-7,7% en poids d'antimoine (Sb) et  7.3% -7.7% by weight of antimony (Sb) and
1 ,3%-1 ,7% en poids de cuivre (Cu). De manière préférée, l’alliage comprenant : 1.3% -1.7% by weight of copper (Cu). Preferably, the alloy comprising:
90,5%-91 ,5% en poids d’étain (Sn),  90.5% -91.5% by weight of tin (Sn),
7,3%-7,7% en poids d'antimoine (Sb) et  7.3% -7.7% by weight of antimony (Sb) and
1 ,3%-1 ,7% en poids de cuivre (Cu).  1.3% -1.7% by weight of copper (Cu).
L’invention concerne aussi un alliage composite pour brasure comprenant un alliage de brasure tel que présenté précédemment et 5%-25% en poids de particules d’argent ou de cuivre. De manière préférée, l’alliage composite pour brasure est constitué uniquement d’un alliage de brasure et de particules d’argent ou de cuivre. Un tel alliage composite de brasure permet d’améliorer la conductivité thermique et électrique. The invention also relates to a composite alloy for brazing comprising a brazing alloy as presented above and 5% -25% by weight of silver or copper particles. Preferably, the composite alloy for brazing consists only of an alloy of brazing and particles of silver or copper. Such a composite alloy of solder improves the thermal and electrical conductivity.
De manière préférée, les particules d’argent ou de cuivre possèdent des dimensions comprises entre 1 et 30 micromètres. Preferably, the silver or copper particles have dimensions between 1 and 30 micrometers.
L’invention concerne également l’utilisation d'un alliage tel que présenté précédemment pour un procédé de refusion de composants électroniques. The invention also relates to the use of an alloy as presented above for a process for remelting electronic components.
L’invention concerne également l’utilisation d'un alliage tel que présenté précédemment pour souder un boîtier de composants électroniques et / ou un dispositif de montage en surface (SMD) à un substrat, l'alliage étant appliqué sous forme de pâte. The invention also relates to the use of an alloy as presented above for soldering a housing of electronic components and / or a surface mounting device (SMD) to a substrate, the alloy being applied in the form of a paste.
DESCRIPTION D’UN OU PLUSIEURS MODES DE REALISATION ET DE MISE EN OEUVRE DESCRIPTION OF ONE OR MORE MODES OF IMPLEMENTATION AND IMPLEMENTATION
Il est proposé un alliage de brasure pour le brasage à la vague, pour le brasage sélectif et notamment pour un procédé de brasage de composants électroniques par refusion. Un tel alliage peut également être utilisé pour la fabrication ou la connexion de composants électroniques, notamment, des semiconducteurs. A brazing alloy is proposed for wave soldering, for selective soldering and in particular for a method of soldering electronic components by reflow. Such an alloy can also be used for the manufacture or connection of electronic components, in particular, semiconductors.
Selon l’invention, il est proposé un alliage de brasure sans plomb ayant une composition comprenant : According to the invention, there is provided a lead-free solder alloy having a composition comprising:
- 86%-94% en poids d’étain (Sn),  - 86% -94% by weight of tin (Sn),
- 5%-10% en poids d'antimoine (Sb) et  - 5% -10% by weight of antimony (Sb) and
1 %-4% en poids de cuivre (Cu).  1% -4% by weight of copper (Cu).
On obtient avantageusement une plage de fusion entre 220°C et 340°C. Advantageously, a melting range between 220 ° C. and 340 ° C. is obtained.
De préférence, l’alliage comprend : - 88%-94% en poids d’étain (Sn), Preferably, the alloy comprises: - 88% -94% by weight of tin (Sn),
- 6%-9% en poids d'antimoine (Sb) et  - 6% -9% by weight of antimony (Sb) and
- 0,5%-2,5% en poids de cuivre (Cu).  - 0.5% -2.5% by weight of copper (Cu).
De préférence, l’alliage comprend : Preferably, the alloy comprises:
- 88,5%-93,5% en poids d’étain (Sn),  - 88.5% -93.5% by weight of tin (Sn),
- 6%-9% en poids d'antimoine (Sb) et  - 6% -9% by weight of antimony (Sb) and
- 0,5%-2,5% en poids de cuivre (Cu).  - 0.5% -2.5% by weight of copper (Cu).
Un tel alliage de brasure présente un point de fusion qui se situe entre 220°C et 310°C et présente de très bonnes propriétés dans les domaines mécaniques, électrique et de mouillage. En outre, l’absence de plomb permet de respecter les nouvelles normes environnementales. Such a brazing alloy has a melting point which is between 220 ° C and 310 ° C and has very good properties in the mechanical, electrical and wetting fields. In addition, the absence of lead makes it possible to comply with the new environmental standards.
De préférence encore, l’alliage comprend : More preferably, the alloy comprises:
- 88%-93% en poids d’étain (Sn),  - 88% -93% by weight of tin (Sn),
- 6%-9% en poids d'antimoine (Sb) et  - 6% -9% by weight of antimony (Sb) and
1 %-3% en poids de cuivre (Cu).  1% -3% by weight of copper (Cu).
On obtient avantageusement une plage de fusion entre 220°C et 300°C. Advantageously, a melting range between 220 ° C. and 300 ° C. is obtained.
De préférence, l’alliage comprend : Preferably, the alloy comprises:
- 90%-92% en poids d’étain (Sn),  - 90% -92% by weight of tin (Sn),
- 7%-8% en poids d'antimoine (Sb) et  - 7% -8% by weight of antimony (Sb) and
1 %-2% en poids de cuivre (Cu).  1% -2% by weight of copper (Cu).
De préférence, l’alliage est constitué de : Preferably, the alloy consists of:
- 90% en poids d’étain (Sn),  - 90% by weight of tin (Sn),
- 8% en poids d'antimoine (Sb) et  - 8% by weight of antimony (Sb) and
- 2% en poids de cuivre (Cu).  - 2% by weight of copper (Cu).
On obtient avantageusement une plage de fusion entre 220°C et 250°C Advantageously, a melting range between 220 ° C. and 250 ° C. is obtained.
De préférence, l’alliage est constitué de : Preferably, the alloy consists of:
- 90% en poids d’étain (Sn),  - 90% by weight of tin (Sn),
- 9% en poids d'antimoine (Sb) et  - 9% by weight of antimony (Sb) and
1 % en poids de cuivre (Cu). On obtient avantageusement une plage de fusion entre 220°C et 240°C 1% by weight of copper (Cu). Advantageously, a melting range between 220 ° C. and 240 ° C. is obtained.
De préférence encore, l’alliage comprend : More preferably, the alloy comprises:
- 90,5%-91 ,5% en poids d’étain (Sn),  - 90.5% -91.5% by weight of tin (Sn),
- 7,3%-7,7% en poids d'antimoine (Sb) et  - 7.3% -7.7% by weight of antimony (Sb) and
1 ,3%-1 ,7% en poids de cuivre (Cu).  1.3% -1.7% by weight of copper (Cu).
De préférence encore, l’alliage comprend : More preferably, the alloy comprises:
- 90,6%-91 ,4% en poids d’étain (Sn),  - 90.6% -91.4% by weight of tin (Sn),
- 7,3%-7,7% en poids d'antimoine (Sb) et  - 7.3% -7.7% by weight of antimony (Sb) and
1 ,3%-1 ,7% en poids de cuivre (Cu).  1.3% -1.7% by weight of copper (Cu).
Un tel alliage de brasure possède des températures de fusion et des diagrammes de phase qui sont optimaux pour mettre en oeuvre un procédé de refusion. Par comparaison à un alliage SAC classique, c’est-à-dire un alliage Etain-Argent-Cuivre, la résistance mécanique est augmentée de plus de 50%, les performances de mouillage sont augmentées et la conductivité thermique est augmentée. De manière avantageuse, le coût d’un alliage selon l’invention est réduit de manière importante, de préférence, de l’ordre de 50%. Such a brazing alloy has melting temperatures and phase diagrams which are optimal for implementing a reflow process. Compared to a conventional SAC alloy, i.e. a Tin-Silver-Copper alloy, the mechanical resistance is increased by more than 50%, the wetting performance is increased and the thermal conductivity is increased. Advantageously, the cost of an alloy according to the invention is reduced significantly, preferably on the order of 50%.
L’alliage selon l’invention a été réalisée dans des tubes de quartz fermés sous vide pour éviter le phénomène d'oxydation, puis dans des creusets en alumine. Des éléments de haute pureté, Sn (99,949%), Sb (99,76%) et Cu (99,99%) ont été introduits et mélangés après la pesée dans les creusets, puis placés dans un four à résistance à une température de 370°C. The alloy according to the invention was produced in quartz tubes closed under vacuum to avoid the phenomenon of oxidation, then in alumina crucibles. Elements of high purity, Sn (99.949%), Sb (99.76%) and Cu (99.99%) were introduced and mixed after weighing in the crucibles, then placed in a resistance oven at a temperature of 370 ° C.
Afin de s'assurer que la composition chimique de l'alliage est conforme au but recherché, elle a été analysée selon deux techniques : la fluorescence X (XRF) et la spectrométrie à dispersion dispersive (EDS) dans un microscope électronique à balayage (SEM). Les analyses par fluorescence X ont été effectuées sur un appareil du type Bruker S4 Explorer équipé d’un tube en rhodium sous une tension d’accélération de 50 kV. La zone balayée avait un diamètre cylindrique de 18 mm et une profondeur d'environ 5 microns. La microstructure a été observée à l'aide d'un pistolet à émission de champ SEM JEOL 7001 F LV couplé à un détecteur de diffraction à rétrodiffusion d'électrons (EBSD) et à un détecteur XMax 50 mm2 SDD EDS. La méthode des anneaux de diffraction des rayons X à haute énergie a également été utilisée à l’Installation européenne de rayonnement synchrotron (ESRF) à Grenoble. Les analyses DSC ont ensuite permis de déterminer les températures de solidus et de liquidus ainsi que l'enthalpie de fusion à partir d'échantillons d'une masse d'environ 50 mg dans des creusets cylindriques en aluminium de 30 pl. Le cycle de test comprend deux échauffements et refroidissement entre 20°C et 350°C avec une vitesse de 5°C / min. De manière avantageuse, l’alliage présente une bonne résistance aux chocs thermiques entre -40°C et +150°C. In order to ensure that the chemical composition of the alloy complies with the desired objective, it was analyzed using two techniques: X-ray fluorescence (XRF) and dispersive dispersion spectrometry (EDS) in a scanning electron microscope (SEM) ). The X-ray fluorescence analyzes were carried out on a Bruker S4 Explorer type device equipped with a rhodium tube at an acceleration voltage of 50 kV. The scanned area had a cylindrical diameter of 18 mm and a depth of about 5 microns. The microstructure was observed using a SEM JEOL 7001 F LV field emission gun coupled to an electron back scattering diffraction detector (EBSD) and to an XMax 50 mm2 SDD EDS detector. The high energy X-ray diffraction ring method was also used at the European Synchrotron Radiation Facility (ESRF) in Grenoble. The DSC analyzes then made it possible to determine the solidus and liquidus temperatures as well as the enthalpy of fusion from samples with a mass of approximately 50 mg in 30 μl cylindrical aluminum crucibles. The test cycle includes two heating and cooling periods between 20 ° C and 350 ° C with a speed of 5 ° C / min. Advantageously, the alloy has good resistance to thermal shock between -40 ° C and + 150 ° C.
Les mesures de mouillabilité ont été effectuées avec une balance de mouillage. Pour mettre en oeuvre cette méthode, une plaque rectangulaire d'un substrat est plongée dans la brasure fondue ayant une profondeur définie et la force est mesurée pendant le test. La procédure de préparation de chaque échantillon avant l’essai consiste en un nettoyage / dégraissage à l’acétone suivi d’une attaque chimique avec une solution aqueuse d’acide nitrique à 2%, d’un rinçage à l’eau distillée et d’une immersion dans un flux de CA (colophane activé) (ECOFREC™ CMA 185 d’Inventec). The wettability measurements were carried out with a wetting balance. To implement this method, a rectangular plate of a substrate is immersed in the molten solder having a defined depth and the force is measured during the test. The procedure for preparing each sample before the test consists of cleaning / degreasing with acetone followed by a chemical attack with a 2% aqueous solution of nitric acid, rinsing with distilled water and d '' immersion in a flow of CA (activated rosin) (ECOFREC ™ CMA 185 from Inventec).
La capacité d'un liquide à s'étaler sur une surface est caractérisée par l'angle entre la surface du substrat et une gouttelette déposée sur la surface. Plus l'angle est petit, meilleure est la mouillabilité. Si la mouillabilité est supérieure à 90°, la mouillabilité est nulle. Selon l’invention, l’angle de mouillabilité est fermé à 20° dans notre cas (entre 25° et 35° pour le SAC305). The ability of a liquid to spread over a surface is characterized by the angle between the surface of the substrate and a droplet deposited on the surface. The smaller the angle, the better the wettability. If the wettability is greater than 90 °, the wettability is zero. According to the invention, the wetting angle is closed at 20 ° in our case (between 25 ° and 35 ° for the SAC305).
L’alliage a été préparé sous forme d’éprouvettes cylindriques pour les essais de traction (selon la norme ISO 6892) qui ont été directement coulées dans un moule en acier inoxydable. La conductivité thermique a été mesurée par la méthode du disque chaud. Un capteur de nickel en spirale est placé entre deux échantillons cylindriques de l'alliage à mesurer. Ces échantillons, de 10 mm de hauteur et de 35 mm de diamètre, doivent présenter une face plane pour améliorer le contact avec le capteur. Ce capteur remplit une première fonction de chauffage et une deuxième fonction de mesure. Pour ce type de mesure, la taille de l'échantillon est directement liée à la conductivité attendue de l'échantillon. The alloy was prepared in the form of cylindrical test pieces for the tensile tests (according to ISO 6892) which were directly cast in a stainless steel mold. The thermal conductivity was measured by the hot disc method. A spiral nickel sensor is placed between two cylindrical samples of the alloy to be measured. These samples, 10 mm high and 35 mm in diameter, must have a flat face to improve contact with the sensor. This sensor fulfills a first heating function and a second measurement function. For this type of measurement, the sample size is directly linked to the expected conductivity of the sample.
Les essais de traction ont été réalisés avec une machine d’essai de traction équipée d’un capteur de charge de 5 kN et d’un extensomètre de 25 mm, avec une vitesse de déformation de 3.10-2 s-1 (0,75 mm / min). The tensile tests were carried out with a tensile testing machine equipped with a load sensor of 5 kN and a strain gauge of 25 mm, with a strain rate of 3.10-2 s-1 (0.75 mm / min).
Les propriétés mécaniques ont été déterminées par trois essais de traction à la microdureté à la température ambiante. Pour cet alliage, la microdureté a été mesurée avec un pénétrateur Vickers sous une charge de 10 N pendant 10 secondes. La valeur moyenne est d'environ 23HV au lieu de 6HV et 18HV pour Tin et SAC 05, respectivement. Le comportement mécanique est similaire à celui du SAC305, sans durcissement. De manière avantageuse, l’élongation maximale est inférieure à 35%, de préférence, de l’ordre de 34%, l’élongation maximale étant de l’ordre de 38% pour un alliage SAC classique. La résistance mécanique de l’alliage selon l’invention est supérieure à 60 MPa, de préférence de l’ordre de 70 MPa, ce qui est supérieure à celle d’un alliage SAC classique qui est de l’ordre de 50 MPa. The mechanical properties were determined by three tensile tests at microhardness at room temperature. For this alloy, the microhardness was measured with a Vickers indenter under a load of 10 N for 10 seconds. The average value is around 23HV instead of 6HV and 18HV for Tin and SAC 05, respectively. The mechanical behavior is similar to that of SAC305, without hardening. Advantageously, the maximum elongation is less than 35%, preferably of the order of 34%, the maximum elongation being of the order of 38% for a conventional SAC alloy. The mechanical strength of the alloy according to the invention is greater than 60 MPa, preferably of the order of 70 MPa, which is greater than that of a conventional SAC alloy which is of the order of 50 MPa.
La conductivité thermique l, qui est l’un des paramètres prédominants d’un alliage de brasage en microélectronique, car elle garantit une bonne dissipation de la chaleur induite par le courant, a été déterminée par la méthode du disque chauffant. De manière préférée, la conductivité thermique supérieure à BOW.m-i.K 1 , de préférence, comprise entre 60W. m-l.K 1et 65W. m-i.K 1 . Une valeur moyenne de 63,60 W. m-i.K 1 avec un écart-type de 0,05 W. m-i.K 1 a été obtenue par trois mesures effectuées sur le même échantillon. The thermal conductivity l, which is one of the predominant parameters of a soldering alloy in microelectronics, since it guarantees good dissipation of the heat induced by the current, has been determined by the heating disc method. Preferably, the thermal conductivity greater than BOW.m- i .K 1 , preferably between 60W. m- l .K 1 and 65W. m- i .K 1 . An average value of 63.60 W. m- i .K 1 with a standard deviation of 0.05 W. m- i .K 1 was obtained by three measurements carried out on the same sample.
Bien que l'utilisation en tant que pâte à braser soit particulièrement préférée, l'alliage peut être utilisé en soudage à la vague, brasage sélectif, brasage au trempé, en tant que partie de fil, pour le placement de CMS et pour des applications pâte-en-pâte. Although use as solder paste is particularly preferred, the alloy can be used in wave soldering, selective soldering, dip soldering, as part of wire, for placement of CMS and for applications dough-in-dough.
De manière préférée, l’alliage est conditionné sous forme de barres, de préformes, de lingots, de poudre, de pâte à braser ou de crème à braser. Preferably, the alloy is packaged in the form of bars, preforms, ingots, powder, solder paste or solder cream.
De manière optionnelle, pour rendre une brasure plus conductrice thermiquement et électriquement, afin de faciliter notamment la dissipation de chaleur au niveau de la jonction, il est proposé de mélanger à l’alliage selon l’invention avec des particules d’argent ou de cuivre ayant une dimension comprise entre 1 et 30 micromètres afin de former un alliage composite. De préférence, des particules d’argent ou de cuivre sont ajoutées à hauteur de 5 à 25% en poids du mélange. Ces particules d’argent ou de cuivre contribuent à augmenter la conductivité thermique et électrique afin de faciliter notamment la dissipation de chaleur au niveau de la jonction avec des composants électroniques. Optionally, to make a solder more thermally and electrically conductive, in order to facilitate in particular the dissipation of heat at the junction, it is proposed to mix the alloy according to the invention with silver or copper particles having a dimension between 1 and 30 micrometers in order to form a composite alloy. Preferably, silver or copper particles are added in an amount of 5 to 25% by weight of the mixture. These silver or copper particles help to increase thermal and electrical conductivity, in particular to facilitate heat dissipation at the junction with electronic components.

Claims

REVENDICATIONS
1. Alliage de brasure sans plomb ayant une composition comprenant : 1. Lead-free solder alloy having a composition comprising:
• 86%-94% en poids d’étain (Sn),  • 86% -94% by weight of tin (Sn),
• 5%-10% en poids d'antimoine (Sb) et  • 5% -10% by weight of antimony (Sb) and
• 0,5%-4% en poids de cuivre (Cu), de préférence, entre 1 % et 4%..  • 0.5% -4% by weight of copper (Cu), preferably between 1% and 4%.
2. Alliage selon la revendication 1 comprenant : 2. Alloy according to claim 1 comprising:
• 88%-94% en poids d’étain (Sn),  • 88% -94% by weight of tin (Sn),
• 6%-9% en poids d'antimoine (Sb) et  • 6% -9% by weight of antimony (Sb) and
• 0,5%-2,5% en poids de cuivre (Cu).  • 0.5% -2.5% by weight of copper (Cu).
3. Alliage selon la revendication 1 comprenant : 3. Alloy according to claim 1 comprising:
• 88%-93% en poids d’étain (Sn),  • 88% -93% by weight of tin (Sn),
• 6%-9% en poids d'antimoine (Sb) et  • 6% -9% by weight of antimony (Sb) and
• 1%-3% en poids de cuivre (Cu).  • 1% -3% by weight of copper (Cu).
4. Alliage selon l’une des revendications 1 à 3 comprenant uniquement de l’étain (Sn), de l’antimoine (Sb) et du cuivre (Cu). 4. Alloy according to one of claims 1 to 3 comprising only tin (Sn), antimony (Sb) and copper (Cu).
5. Alliage selon la revendication 1 comprenant : 5. Alloy according to claim 1 comprising:
• 90%-92% en poids d’étain (Sn),  • 90% -92% by weight of tin (Sn),
• 7%-8% en poids d'antimoine (Sb) et  • 7% -8% by weight of antimony (Sb) and
• 1%-2% en poids de cuivre (Cu).  • 1% -2% by weight of copper (Cu).
6. Alliage selon la revendication 1 comprenant 90%-92% en poids d’étain (Sn). 6. Alloy according to claim 1 comprising 90% -92% by weight of tin (Sn).
7. Alliage selon la revendication 1 comprenant 7%-8% en poids d'antimoine (Sb). 7. Alloy according to claim 1 comprising 7% -8% by weight of antimony (Sb).
8. Alliage selon la revendication 1 comprenant 1 %-2% en poids de cuivre (Cu). 8. Alloy according to claim 1 comprising 1% -2% by weight of copper (Cu).
9. Alliage selon la revendication 1 comprenant : 9. Alloy according to claim 1 comprising:
• 90,6%-91 ,4% en poids d’étain (Sn),  • 90.6% -91.4% by weight of tin (Sn),
• 7,3%-7,7% en poids d'antimoine (Sb) et  • 7.3% -7.7% by weight of antimony (Sb) and
• 1 ,3%-1 ,7% en poids de cuivre (Cu). • 1.3% -1.7% by weight of copper (Cu).
10. Alliage composite pour brasure comprenant : 10. Composite alloy for brazing comprising:
• un alliage de brasure selon l’une des revendications 1 à 9 et  • a brazing alloy according to one of claims 1 to 9 and
• 5%-25% en poids de particules d’argent ou de cuivre.  • 5% -25% by weight of silver or copper particles.
11. Alliage composite pour brasure selon la revendication 10 dans lequel les particules d’argent ou de cuivre possèdent des dimensions comprises entre 1 et 30 micromètres. 11. A composite alloy for solder according to claim 10 wherein the silver or copper particles have dimensions between 1 and 30 micrometers.
12. Utilisation d'un alliage selon l’une des revendications 1 à 9 pour un procédé de refusion de composants électroniques. 12. Use of an alloy according to one of claims 1 to 9 for a process for remelting electronic components.
13. Utilisation d'un alliage selon l’une des revendications 1 à 9 pour souder un boîtier de composants électroniques et / ou un dispositif de montage en surface (SMD) à un substrat, l'alliage étant appliqué sous forme de pâte. 13. Use of an alloy according to one of claims 1 to 9 for soldering a housing of electronic components and / or a surface mounting device (SMD) to a substrate, the alloy being applied in the form of a paste.
EP19797182.3A 2018-10-19 2019-10-17 Lead-free solder alloy and use of such an alloy Pending EP3867005A1 (en)

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JP2005122970A (en) * 2003-10-15 2005-05-12 Matsushita Electric Ind Co Ltd Vessel
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