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
• • 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
  • B23K2101/00—Articles made by soldering, welding or cutting
  • B23K2101/36—Electric or electronic devices

Definitions

• the invention relates to a lead-free soft solder, in particular for use in electronics and electrical engineering.
• the soft solders used in electronics and electrical engineering should not only have good wetting behavior compared to the metallic components to be thermally joined, but should also have the lowest possible electrical resistance in the seam transition and the greatest possible alternating strength, so that even soft materials with very different thermal expansion coefficients can be joined with these soft solders can be. It is also of particular importance that the melting points or melting ranges of the solders are on the one hand sufficiently above the maximum operating temperatures, but at the same time are so low that the components to be joined by soft soldering are not damaged as a result of the melting temperatures required for the joining process with these solders , In addition, for optimal soldering behavior, it is advantageous if the alloys used as solders have eutectic or almost eutectic properties.
• solders that are to be used for the production of BGA balls (solder balls for chip production)
• a smooth, homogeneous surface of the solder joint is also imperative, so in the frame an effective quality control of the solder joints, which can be optically evaluated quickly and without errors due to their gloss.
• BGA balls ball-grid array
• bismuth also increases the ductility and severely limits the desired elasticity of the solder balls.
• These solders have low shear and creep strength.
• the eutectic melting temperature of the 'base solder of 216.8 ° C is not changed.
• solder alloy causes the bridging of relatively wide soldering gaps due to the formation of Cu 3 Sn and / or Cu 6 Sn 5 needles, but the formation of these intermetallic phases inevitably has the disadvantages already described with regard to the suitability for soldering and mechanical / physical properties of the solder joint result.
• Rust formation tends and therefore cannot be used in the field of electronics.
• Cooling process tend very strongly to the formation of coarse tin centrids, and consequently inherent the resulting disadvantages.
• Solder variants also tend to form coarse tin centrids and in no way are they optimal for use as BGA balls
• the invention is therefore based on the object of eliminating the disadvantages of the prior art, and of developing a lead-free soft solder, the melting and solidification range of which, on the one hand, is eutectic starting at 214 ° C., but on the other hand can be expanded upwards by means of targeted doping and simultaneously under no circumstances tends to form coarse tin centrids; after melting, a smooth and homogeneous surface of the solder is guaranteed, as well as very good physical and chemical properties such as, for example, very good wettability, high fatigue strength, good corrosion resistance, good plasticity and toughness has a low electrical resistance and is suitable for use as BGA balls (solder balls for chip production).
• this object is achieved by a lead-free Sn-Ag-Cu solder alloy, which is characterized in that it consists of a base alloy with 5 to 20% by weight of silver, 0.8 to 1, 2% by weight of copper, The rest is tin and the usual impurities, this base alloy always 0.8 to 1.2% by weight indium and
• Elements of the lanthanoids such as lanthanum or neodymium are alloyed, the latter three variants also being able to be combined with one another in the form of master alloys in such a way that their sum is 0.01 to 0.2% by weight.
• the lead-free soft solder according to the invention obtained with a silver content of 5 to 5.5% by weight has an almost eutectic melting and solidification temperature in the range from a maximum of 214 to 215 ° C, avoids the formation of coarse tin centrids when cooling and always ensures a smooth and homogeneous Surface of the solder.
• the melting range increases with increasing silver content, starting with the eutectic temperature from 214 ° C to 215 ° C.
• solders according to the invention with an almost eutectic melting and solidification temperature that begins at 214 ° C. to 215 ° C. and can be expanded in a defined manner avoid the formation of coarse tin centrids on cooling and always ensure a smooth and homogeneous surface of the soldering point.
• the lead-free soft solder according to the invention is notable for very good physical and chemical properties, such as, for example, very good wettability, high fatigue strength, good corrosion resistance, good plasticity and toughness a low electrical resistance and after melting through a smooth and homogeneous surface of the solder.
• the lead-free soft solder according to the invention is particularly suitable for the production of BGA balls (solder balls for chip production).
• Soft solder consisting of 98.8% by weight of an Sn-5% Ag-1% Cu alloy, and 1% by weight indium with 0.2% by weight nickel.
• Soft solder consisting of 98.8% by weight of an Sn-5% Ag-1% Cu alloy, and 1% by weight indium with a doping of 0.2% by weight lanthanum in the melt is presented in more detail.
• lanthanum according to the invention which is in the form of pure lanthanum or as a master alloy with e.g. Nickel or germanium can occur, the desired eutectic remain due to the overall composition of the invention
• Soft solder alloy in turn ensures that no coarse tin centrids are formed.
• this solder according to the invention also has an improved homogeneous surface, better oxidation behavior and significantly improved mechanical
• a lead-free soft solder was presented, the melting and solidification range of which, on the one hand, is eutectic starting at 214 ° C, but on the other hand can be expanded upwards by means of targeted doping and at the same time does not tend to form coarse tin centrids, after melting a smooth and homogeneous Surface of the solder is guaranteed, is also characterized by very good physical and chemical properties such as, for example, very good wettability, high fatigue strength, good corrosion resistance, good plasticity and toughness as well as low electrical resistance, and for use as BGA balls ( Solder balls for chip production) is suitable.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Electric Connection Of Electric Components To Printed Circuits (AREA)
• Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
• Battery Electrode And Active Subsutance (AREA)
• Organic Insulating Materials (AREA)

Priority Applications (8)

Applications Claiming Priority (2)

Publications (1)

Family

ID=7709452

Family Applications (1)

Country Status (11)

Cited By (3)

Families Citing this family (14)

Citations (5)

Family Cites Families (3)

• 2002
  • 2002-12-10 MX MXPA04005835A patent/MXPA04005835A/es not_active Application Discontinuation
  • 2002-12-10 US US10/498,154 patent/US20050008525A1/en not_active Abandoned
  • 2002-12-10 EP EP02791624A patent/EP1453636B1/de not_active Expired - Lifetime
  • 2002-12-10 CN CNB028249046A patent/CN1310736C/zh not_active Expired - Fee Related
  • 2002-12-10 WO PCT/DE2002/004525 patent/WO2003051572A1/de not_active Ceased
  • 2002-12-10 DE DE50207747T patent/DE50207747D1/de not_active Expired - Lifetime
  • 2002-12-10 JP JP2003552486A patent/JP2005512813A/ja active Pending
  • 2002-12-10 AT AT02791624T patent/ATE334775T1/de not_active IP Right Cessation
  • 2002-12-10 HU HU0402010A patent/HUP0402010A2/hu unknown
  • 2002-12-10 KR KR10-2004-7008958A patent/KR20040063990A/ko not_active Withdrawn
  • 2002-12-10 BR BR0215041-7A patent/BR0215041A/pt not_active Application Discontinuation

Patent Citations (5)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events