Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/001—Heat treatment of ferrous alloys containing Ni
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/10—Ferrous alloys, e.g. steel alloys containing cobalt
  • C22C38/105—Ferrous alloys, e.g. steel alloys containing cobalt containing Co and Ni
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L23/00—Details of semiconductor or other solid state devices
  • H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
  • H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
  • H01L23/495—Lead-frames or other flat leads
  • H01L23/49579—Lead-frames or other flat leads characterised by the materials of the lead frames or layers thereon
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
  • C21D8/0226—Hot rolling
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
  • C21D8/0236—Cold rolling
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
  • C21D8/0268—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment between cold rolling steps
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
  • C21D8/0273—Final recrystallisation annealing
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/0001—Technical content checked by a classifier
  • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Definitions

• Iron-nickel alloy strip for the manufacture of integrated circuit support grids
• the present invention relates to iron-nickel alloy strips that can be used in particular for manufacturing integrated circuit support grids in a wide range of electronic components such as static memories, dynamic or programmable memories and microprocessors.
• the electronic components comprise integrated circuits made from silicon pellets etched and glued on grids intended in particular to form the connecting lugs of these integrated circuits.
• These grids must be made of an alloy having multiple properties making them compatible with silicon pellets called “electronic chips" and allowing the manufacture of components in good conditions.
• the alloy must have a coefficient of thermal expansion slightly greater than that of the silicon to maintain the component in compression during cooling of the thermal cycles of the component manufacturing process and for its use, in order to avoid the occurrence of significant mechanical stresses. s
• the alloy must have a sufficiently high mechanical strength Rm so that the connecting tabs do not deform during manipulations by means of automata.
• Rm mechanical strength
• it must also have good formability, that is to say, on the one hand a sufficient ductility characterized by a total elongation greater than 5% and, on the other hand, a ratio between the elastic limit R p o, 2% and the Young's modulus E sufficiently low to reduce the elastic return during folding of the tabs. All of these features can prevent damage to the legs during their shaping.
• the strip obtained and the tabs manufactured must have the greatest possible dimensional stability after cutting, but also throughout the various thermal cycles of the manufacturing process and during use.
• This dimensional stability passes through low residual stresses in the band to ensure the co-planarity of the inner and outer lugs of the grids, but also by a small shrinkage during the heat treatments used for the manufacture of the components. It is estimated that the shrinkage value on a 180 mm long strip subjected to a heating cycle at 500 ° C. for 4 minutes must in no case exceed 15 ⁇ m, ie a deformation ⁇ r of less than 8 ⁇ 10 -3 %. and preferably for the most demanding components less than 4.10 3 %.
• integrated circuit support grids are made of N42 ® alloy which is an iron-nickel alloy containing about 41% nickel.
• the strips used are obtained by a standard manufacturing process comprising a series of cold rolling operations with intermediate recrystallization annealing, the last operation being a cold rolling whose rate of hardening (or thickness reduction ratio) allows to adjust the mechanical characteristics and in particular the Rm of the future grid.
• the strips obtained however have inadequate characteristics in terms of pliability, but * as dimensional stability, particularly in terms of shrinkage. Indeed, it is commonly observed necking up to 40.10 "3 %, and not falling below 6.10 " 3 %.
• the use is to use strips having undergone additional final heat treatment called stress relieving, at a temperature much lower than the recrystallization temperature, in order to reduce the residual stresses and the shrinkage without significantly lowering mechanical resistance.
• stress relieving at a temperature much lower than the recrystallization temperature, in order to reduce the residual stresses and the shrinkage without significantly lowering mechanical resistance.
• this treatment is not able to reduce shrink below 5.10 "3% nor reduce the total residual stress, which causes problems observable dimensional stability for grids dedicated to the most demanding applications.
• the object of the invention is therefore to provide an iron-nickel alloy strip which is better suited to the manufacture of integrated circuit support grids, and which in particular has improved dimensional stability and foldability characteristics compared to to the solutions of the prior art.
• a first object of the invention is constituted by an iron-nickel alloy strip, comprising in% by weight:
• Mn ⁇ 0.75% the balance being iron and the unavoidable impurities resulting from the preparation, the microstructure of which has a recrystallized volume fraction of between 3 and 97% and a thickness of less than 0.5 mm.
• the alloy strip according to the invention may further comprise any of the following characteristics, taken alone or in combination:
• said microstructure comprises grains in the course of recrystallization, with a maximum diameter of 20 ⁇ m, visible in the electron microscope in
• TEM Transmission
• the strip has a mechanical strength Rm of between 540 and 755 MPa
• the strip has a mechanical strength Rm of between 540 and 600 MPa and a recrystallized volume fraction of between 3 and 97%, preferably between 45 and 95%.
• the strip has a mechanical strength Rm of between 620 and 755 MPa and a recrystallized volume fraction of between 3 and 70%, and preferably between 40 and 70%,
• the band has a shrinkage less than or equal to 4.10 '3 %, and preferably less than or equal to 3.10 ' 3 %, after a test at 500 0 C for 4 minutes.
• a second subject of the invention consists of a method for manufacturing an iron-nickel alloy strip according to the invention, according to which the following successive operations are carried out:
• the iron-nickel alloy which constitutes the strip according to the invention comprises from 32 to 45% by weight of nickel, preferably from 38 to 43% of nickel and more preferably from 40 to 42% of nickel in combination with a cumulative Cu, Co, and Cr content of less than 1%.
• Nickel can be partially replaced by cobalt at a maximum of 6.5% and preferably 4.5%, the minimum cobalt content being 0%.
• the composition may contain up to 3% copper (the minimum content being 0% or traces), in order to improve resistance to corrosion and oxidation by air, but must not exceed this content to not degrade the coefficient of thermal expansion.
• the chromium content of the composition may be up to 6.5% by weight by adjusting the nickel content, but must not exceed this content because it does not degrade the coefficient of thermal expansion and preferably does not exceed 5.5 % in weight.
• This element makes it possible in particular to improve the corrosion resistance of the alloy and its resistance to oxidation during the tinning and brazing phases of the lugs of the grids.
• the contents of nickel, cobalt, copper and chromium are selected to achieve a coefficient of thermal expansion between 20 0 C and any temperature between 20 and 300 0 C, which is between 3.5.10 "6 and 6,5.10" 6 / K.
• the composition also comprises up to 0.5% of silicon and up to 0.75% of manganese, which are optionally introduced during the preparation to ensure the deoxidation of the grade, the minimum contents of these elements being traces.
• the rest of the composition consists of iron and unavoidable impurities from the elaboration.
• the alloy according to the invention may be prepared in an electric arc furnace with a refining phase followed by a heating pouch metallurgy step, for example. It can also be developed in the vacuum induction furnace or by any other suitable method.
• the alloy is then cast as a semi-finished product such as an ingot, billet, slab or reflow electrode.
• a semi-finished product such as an ingot, billet, slab or reflow electrode.
• the alloy is cast as a reflow electrode, it is remelted either under vacuum or electrically conductive slag, to obtain better purity and more homogeneous semi-products.
• the semi-finished product is, according to its section, converted to heat in one or two operations at a temperature greater than 950 ° C., and preferably greater than 1050 ° C., but preferably less than 1300 ° C. to obtain a hot strip.
• the hot transformation operations may include blooming and / or hot rolling, and may be accompanied, if necessary, homogenization heat treatments between 950 0 C and 1300 0 C, these treatments may last from a few minutes to several hours.
• the resulting strip is cooled to a temperature close to room temperature.
• An equivalent band can be obtained directly by continuous casting of thin strip, the process then optionally including in-line hot rolling.
• the cooled strip is then subjected to a first cold rolling operation to obtain a strip whose thickness is, for example, between 1 and 2 mm. This operation can be performed in one or more successive passes.
• the strip may then be subjected to a heat treatment consisting of total recrystallization annealing.
• This treatment can be carried out in a static oven for a period ranging from 10 minutes to several hours and at a temperature greater than 700 ° C. or even in a continuous annealing furnace for a duration ranging from a few seconds to about 1 minute, to a temperature preferably greater than 800 0 C in the holding zone of the oven, and preferably under an inert or reducing atmosphere.
• the strip is completely recrystallized, which makes it possible to obtain a new ductile alloy, with a view to the subsequent work-hardening.
• the strip according to the invention by only performing a cold rolling operation, followed by the final heat treatment of partial recrystallization, without carrying out the total recrystallization annealing just described. If a total recrystallization annealing is carried out, a second cold rolling operation is then carried out in order to obtain a strip whose final thickness is, for example, between 0.05 and 0.5 mm. This operation can be performed in one or more successive passes.
• the partial recrystallization heat treatment is preferably carried out by passing through a passage furnace, preferably under an inert or reducing atmosphere, at a temperature T of between 650 and 825 ° C., and for a period of less than 120 seconds, and preferably at a temperature above 660 ° C. for a duration of less than 60 seconds. More particularly preferably, the temperature of the heat treatment is greater than 695 ° C. for a duration of less than 20 seconds, and more preferably, the temperature is greater than 71 ° C. for a duration of less than 10 seconds.
• the microstructure obtained according to the invention is mixed and comprises, in particular, restored grains and partially recrystallized grains.
• FIG. 1 represents a microstructure, observed by TEM on a thin strip, of a hardened alloy strip according to the prior art
• FIG. 2 represents a microstructure, observed by TEM on a thin plate, of an alloy strip according to the invention
• FIG. 3 represents a microstructure, observed by TEM on a thin plate, of a totally recrystallized alloy strip according to the prior art.
• the recrystallized volume fraction Fvr can in particular be determined by means of the following equation:
• R m mechanical strength of the strip after partial recrystallization treatment.
• microstructure shown ⁇ ⁇ in Figure 2 corresponds to a band according to " an " embodiment of the invention, obtained by the process according to the invention ending in a final heat treatment of partial recrystallization. We observed the presence of restored grains (cell structures) surrounded by partially recrystallized grains (structure without dislocation).
• This embodiment corresponds to the commercial quality called "hard%" which has a mechanical strength Rm of between 540 MPa and 5 600 MPa. Its recrystallized volume fraction is 85% and corresponds to a
• V * hard which has a mechanical strength Rm of between 620 MPa and 755 MPa and can be obtained according to the present invention, in particular by adjusting the recrystallized volume fraction in a range of 3 at 70%. Its typical recrystallized volume fraction is 50% and corresponds to a R m after heat treatment of 660 MPa and, at a R m ° before heat treatment of
• the microstructure shown in FIG. 3 corresponds to an alloy strip according to the prior art, obtained by a conventional method terminating in a final heat treatment of total recrystallization. Its recrystallized volume fraction is therefore 100%.
• microstructure of a strip having undergone thermal stress relief is not different from that of the temper mill of FIG. 1, its recrystallized volume fraction being very close to 0%, and in all cases much lower than 3%.
• a series of samples 0.1 mm thick were made from the same alloy composition comprising 41% nickel, 0.05% cobalt, 0.15% silicon, 0.50% of manganese and 0.05% copper, the balance being iron.
• a first series of samples was manufactured according to the conventional method of the prior art ending with a cold rolling with a work hardening ranging from 10 to 25%.
• a second series of samples was manufactured according to the conventional method of the prior art ending in a stress relieving heat treatment at a temperature of 65O 0 C for a duration of 6 seconds.
• a third series of samples was manufactured according to the invention, by implementing a final heat treatment of partial recrystallization carried out by passing through a passage oven at temperatures between 700 ° and 78 ° C. for less than 10 seconds.
• the necking test is performed on laces of 30x200mm. It consists of three phases:
• the evolution of the hanger that takes a thin strip as a function of the reduction of its thickness by etching or other process, on one side, is a usual method of characterizing the level of residual stresses present in the thickness of the thin products.
• the three sample ranges A 1 A 'and B are taken as defined in Example 1, their yield strength R p o, 2 % , their Young's modulus E, their mechanical strength, are determined and determined. the recrystallized volume fraction.
• the range B according to the invention has a ratio R P o, 2 % / E decreased by 20 to 30% compared to the range A and decreased by 10 to 20% compared to the range A ', d where significantly improved folding ability.
• the samples according to the invention have a total elongation greater than the elongation of the samples according to the prior art.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Metallurgy (AREA)
• Mechanical Engineering (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Physics & Mathematics (AREA)
• Crystallography & Structural Chemistry (AREA)
• Thermal Sciences (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Power Engineering (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Computer Hardware Design (AREA)
• Heat Treatment Of Sheet Steel (AREA)
• Lead Frames For Integrated Circuits (AREA)
• Heat Treatment Of Steel (AREA)

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• 2004
  • 2004-11-05 FR FR0411854A patent/FR2877678B1/fr not_active Expired - Lifetime
• 2005
  • 2005-11-04 US US11/718,649 patent/US8328961B2/en not_active Expired - Fee Related
  • 2005-11-04 CN CNA2005800438833A patent/CN101084321A/zh active Pending
  • 2005-11-04 EP EP05814999A patent/EP1809780A2/fr not_active Withdrawn
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  • 2005-11-04 WO PCT/FR2005/002741 patent/WO2006051188A2/fr not_active Ceased
• 2012
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