CN1220571C - Method for preparing microshere solder and micro spraying device utilized - Google Patents

Method for preparing microshere solder and micro spraying device utilized Download PDF

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Publication number
CN1220571C
CN1220571C CN 02132882 CN02132882A CN1220571C CN 1220571 C CN1220571 C CN 1220571C CN 02132882 CN02132882 CN 02132882 CN 02132882 A CN02132882 A CN 02132882A CN 1220571 C CN1220571 C CN 1220571C
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alloy
pressure
preparation
metal
shower nozzle
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CN1480289A (en
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冼爱平
闵家源
尚建库
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Institute of Metal Research of CAS
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Institute of Metal Research of CAS
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Abstract

The present invention relates to a welding material for electronic packaging, particularly to a preparation method for micro-ball welding fluxes and a micro-spraying device used by the preparation method. The present invention adopts a precise spraying technology in protective media. The molten metal or alloy is directly sprayed into micro-ball drops, and the spherical welding fluxes are prepared from the solidified drops. When the technology is adopted to prepare the BGA (ball grid array) micro-ball welding fluxes, the application range of the ball diameter is from 0.1mm to 1mm. The welding fluxes have the advantages of narrow size distribution, high sphericity, smooth and clean surfaces, high productive efficiency, mass production, low manufacturing cost, etc.

Description

A kind of preparation method of microballoon scolder and used micro-spray device
Technical field
The present invention relates to the welding material of used for electronic packaging, specifically a kind of preparation method of microballoon scolder and used micro-spray device.
Background technology
Along with the develop rapidly of microelectric technique, make the developing direction of modern electronic product have characteristics such as multi-functional, high reliability, miniaturization, lightweight and low cost.And the basis and the core that satisfy these requirements are the more and more higher technology of semiconductor chips of integrated level and associated Electronic Packaging technology.
Along with integrated circuit (Integrated Circuit, abbreviation: IC) characteristic size constantly reduces and the improving constantly of integrated level, IC has developed into ultra-large IC (Very Large Scale Integration, abbreviation: VLSI) stage, but integrated gate circuit up to 1,000,000 so that tens million of/chip, (Input/Output, I/O) number has reached hundreds of, and is the highest above 1000 in wherein I/O.Like this, originally four limit flat package (Quad Flat Package, abbreviation: QFP) and the Electronic Packaging of other types, although lead spacing is dwindled the requirement that (for example QFP reached 0.3mm the technology limit) can not satisfy packaging V LSI again and again.The Electronic Packaging lead-in wire develops into the face formation by peripheral type, as pin grid array encapsulation (Pin Grid Array, abbreviation: PGA).Yet, still have superiority with the LSI (not having Chinese) of the low I/O number of PGA encapsulation, and to encapsulate the VISI of high I/O just powerless when it.The one, volume is too heavy greatly again; The 2nd, complex manufacturing technology and cost height; The 3rd, can not use surface mounting technology (Surface mount Technology, abbreviation: SMT) carry out surface mount, be difficult to realize industrial-scale production.Combine the advantage of QFP and PGA, develop microelectronic packaging technology-BGA of new generation (Ball Grid Array, abbreviation: BGA) encapsulation finally in the early 1990s.So far, the microelectronics Packaging of big always for many years large time delay chip development can adapt to the paces that chip develops finally owing to succeeding in developing of BGA.
So-called BGA uses many soldered balls with arrayed to connect between chip and substrate (or printed circuit board (PCB)) usually.Relatively be typically the array soldered ball between the metallized pads and the metallized pads on the substrate of electronic packing piece.When packaging part and substrate are correctly aimed at and relative fixed after, just the method with reflow welding melts soldered ball, and utilize interface wetting power between brazing metal and the metal pad, and carry out accurate position correction, between packaging part and substrate, form accurately after the cooling and reliably be connected.
Based on the large-scale industrial application of above-mentioned BGA technology, the key electronic material in this technology is a kind of alloys welding balls of single size.
Make the existing multiple invention technology of tiny soldered balls.Representational technology comprises: 1) direct casting (United States Patent (USP), application number: 5,388,327 and 5,381,848), the problem of existence is that casting process is difficult to control, and spherical circularity is undesirable; 2) part is blocked lead fusion method (United States Patent (USP), application number: 4,661,192 and 3,380,155), its technology is earlier raw material to be drawn wire, and is cut into segment again, then with segment type material heat fused, make it under surface tension effects, become ball-type, its main deficiency is that the requirement solder alloy has good wire drawing deformability, and the own plasticity deficiency of solder alloy else if is as tin bismuth eutectic solder, then wire drawing difficulty, this technology just can't be carried out; 3) soldering paste printing circumfluence method (United States Patent (USP), application number: 5024,372 and 5,133,495), the formation of soldered ball is on off-the-shelf array pad, with masterplate with the coating of a certain amount of soldering paste after, through reflow welding stove heat fused, under surface tension effects, on pad, form local salient point, the shortcoming of this technology is a complex technical process, requires expensive equipment; 4) section remelting process, sheet metal is cut into the fragment of certain size, and each small pieces is placed on the ceramic anchor clamps with the recess that can assemble the motlten metal microballoon heats remelting, make it the method (Japan Patent of balling-up, application number: 4-262895), the major defect of this technology is that technical process is very complicated, and production efficiency is very low.
Summary of the invention
But the purpose of this invention is to provide the good mass production of simple, the spherical circularity of a kind of technology, be applicable to microballoon scolder preparation method and used micro-spray device that the microelectronics BGA Package is used.
To achieve these goals, technical scheme of the present invention is as follows:
Preparation method: adopt the micro-injection technology; in protective medium, use gases at high pressure the direct injection liquid metal or the alloy raw material of heat fused; the metal or alloy spherical solder of preparation narrow size distribution; be specially: the metal or alloy raw material is heated to more than the metal or alloy fusing point 5 ℃~50 ℃, and expulsion pressure is 6.89476 * 10 4Pa~5.51580 * 10 5Pa sprays liquid metal or alloy raw material, Sustainable Control pressure and temperature in course of injection in protective medium; The spray nozzle diameter that adopts is φ 0.01~φ 0.8mm, is under 0.5~30 condition in shower nozzle aspect ratio excursion, obtains the little shape spherical solder of metal or alloy of narrow size distribution; After the cooling, take out microballoon;
The described expulsion pressure that applies can be continuous or intermittence, and the injection cycle that the latter adopts is 0.001~1s; Described protective medium can be Ar or N 2, also can be organic solvent; Described organic solvent is vegetable and animals oils or mineral oil;
Its micro-spray device: be installed on the support, mainly by air supply system, airtight furnace chamber, crucible, temperature controller, heating furnace, shower nozzle, collecting pipe, collecting box are formed, wherein: the collecting pipe of sealing is the workspace, inside is filled with protective medium, its first half outside is provided with heating furnace, and heating furnace links to each other with temperature controller; The metal or alloy raw material is contained in the crucible, and crucible is positioned at airtight furnace chamber, and a shower nozzle is equipped with in airtight furnace chamber lower end, inserts in the collecting pipe, and airtight furnace chamber upper end is connected with air supply system by gas conduit; Gas control system is made up of high-pressure air source, air valve, pressure controller, and wherein high-pressure air source is carried out switch control by air valve and exported pressed gas to pressure controller; The supply gas pressure of air supply system is 6.89476 * 10 4Pa~5.51580 * 10 5Pa according to the size of preparation solder metal or alloying pellet, selects different injection diameters, has at least one spray orifice on the described shower nozzle, and the diameter of spray orifice is φ 0.01~φ 0.8mm on the shower nozzle, and the spray orifice shape can be circular, square, triangle or polygon; The aspect ratio excursion of spray nozzle is 0.5~30.
The present invention has following advantage:
In the industrial preparation technology of single size BGA soldered ball, compare with method in the prior art, it is easy to adopt the inventive method to have technology, control easily, sphere diameter is adjustable, spherical circularity good (deflection measurements of diameter on each diametric(al) to ball is: its deviation is less than 3%), its narrow size distribution, any surface finish, and, make low cost of manufacture, to the alloying component wide adaptability owing to adopt bulk alloy, characteristics such as can be mass-produced are applicable to the needs of hyundai electronics encapsulation (BGA) technology.
Description of drawings
Fig. 1 is the used soldered ball injection apparatus of a present invention structural representation.
Fig. 2 is the prepared scolder diameter of micro ball distribution situation of one embodiment of the invention.
Fig. 3 is the prepared deflection measurements of scolder diameter of micro ball on each diametric(al) of one embodiment of the invention.
Fig. 4 is the ESEM shape appearance figure of the prepared scolder microballoon of one embodiment of the invention.
The specific embodiment
By embodiment in detail the present invention is described in detail below in conjunction with accompanying drawing.
Embodiment 1
As shown in Figure 1, the used injection apparatus of the present invention is installed on the steel bracket 13, its structure mainly is made up of high-pressure air source, airtight furnace chamber 6, crucible 15, temperature controller 7, heating furnace 9, shower nozzle 10, collecting pipe 11, wherein: the collecting pipe 11 of sealing is as the workspace, inside is filled with protective medium, prevent the oxidation of metal surface, its first half outside is provided with heating furnace 9, and heating furnace 9 links to each other with temperature controller 7; Airtight furnace chamber 6 and crucible 15 are arranged in the heating furnace 9, crucible 15 is structure as a whole with airtight furnace chamber 6, (described crucible 15 also can be absolute construction to be positioned at airtight furnace chamber 6 bottoms, be positioned over airtight furnace chamber 6 bottoms in addition), a shower nozzle 10 is equipped with in airtight burner hearth 6 lower ends, and insert the sealing collecting pipe 11 of bottom, and airtight furnace chamber 6 upper ends link to each other with air supply system by gas conduit 4, and a collecting box 14 is established in collecting pipe 11 lower ends; Metal or alloy raw material 8 is contained in the crucible 6; Establish a thermometer 5 on the heating furnace 9;
Described air supply system is made up of high-pressure air source 1 (as gas cylinder or air pump), air valve 2, pressure controller 3, and wherein high pressure gas 1 is carried out switch control by air valve 2 and exported pressed gas to pressure controller 3; Wherein: temperature controller 7, pressure controller 3 are the commercially available prod.
Described metal or alloy raw material 8 is low-melting-point metal or alloy, concrete melting range is 100 ℃~350 ℃, as Sn base alloy and Pb base alloy, comprise Sn, Pb, Sn-Cu alloy, Sn-Pb alloy, Pb-Sn alloy, Sn-Bi alloy, Sn-Ag alloy and Sn-Ag-Cu alloy.
The diameter of spray orifice is φ 0.01~φ 0.8mm on the described shower nozzle, and the spray orifice shape can be circular, square, triangle or polygon; The aspect ratio excursion of spray nozzle is 0.5~30.1 little spray orifice is arranged on the shower nozzle 10 in the present embodiment, and diameter is φ 0.12mm; Aspect ratio is 20, and spray orifice is shaped as circle.
The device course of work of the present invention:
At first metal or alloy raw material 8 is packed in the crucible 15; then with airtight furnace chamber 6 upper end closeds; and fill with inert gas or other protective medium; in case metal or alloy oxidation; to heating furnace 9 energising heating; when heating furnace 9 energisings; metal or alloy raw material 8 in the crucible 15 is heated fusing; heating-up temperature is measured by thermometer 5; and regulate and control by temperature controller 7, temperature is slowly risen, when surpassing the metal or alloy fusing point, (generally surpass 5~50 ℃ of fusing points) insulation a period of time; open air valve 2; regulate gas pressure, at this moment just have metal or alloy to drip 12 and begin from shower nozzle 10 ejections, metal or alloy drips 12 after shower nozzle 10 ejections; making free fall type in collecting pipe 11 descends; because the effect of liquid metal or alloy surface tension force forms the ball drop, and cooling cooling gradually; last microballoon begins to solidify, and is deposited to collecting pipe 11 bottoms.After the collecting box 14 of collecting pipe 11 bottoms has accumulated the microballoon of q.s, with its taking-up, sieve or use the additive method classification, the circularity that so just can obtain certain size reaches the low-melting-point metal or the alloy microballoon of standard.
Its preparation method: adopt the micro-injection technology, direct injection liquid metal or alloy raw material 8 in protective medium, the metal or alloy spherical solder of preparation narrow size distribution is specially: adopt the Pb-Sn (Sn63%, Pb37%) alloy raw material that prepare, fusing point is 183 ℃, alloy is added in the crucible 15, and protective medium is No. 10 machine oil in the collecting pipe 11, after the charging, with airtight furnace chamber 6 upper end closeds, and insert high-pressure air source; Be heated to 210 ℃ by temperature controller 7,9 pairs of alloys of heating furnace, programming rate is 6 ℃/minute, and heating finishes, and keeps this temperature 15 minutes, opens air valve 2, and present embodiment is regulated pressure with gas pressure controller 3, and pressure is adjusted to 1.03421 * 10 5Pa (described expulsion pressure be applied for continuation mode); at this moment in protective medium; the spray orifice of shower nozzle 10 begins to have the bead ejection; continue described controlled pressure and temperature in the course of injection; make its state that is consistent; obtain the molten drop of desired size; these molten drops fall into the oil cooling and landing downwards under the gravity effect; simultaneously under the operation of nature of surface tension of liquid; form the good globule of profile, finally solidify the miniature solder ball of formation, after alloy raw material 8 has sprayed fully; stop heating furnace 9; naturally cooling is taken out the alloy microballoon of the different size that obtains in the collecting pipe 11 from collecting box 14.
Described " microballoon " diameter that refers to is the metal or alloy ball of 100 μ m~1000 μ m.The microballoon of technical process manufacturing of the present invention has certain sphere diameter and distributes, if need the ball of single size, then needs to sieve or adopts additive method to carry out classification.The technology of classification is not included within the present invention.
Present embodiment records sphere diameter and is distributed as 700 μ m~840 μ m, and microballoon has the sphere diameter of certain limit to distribute, and the diameter of micro ball distribution situation is referring to Fig. 2, and the microballoon that obtains can sieve or use the additive method classification.The deviation of diameter of micro ball on each diametric(al) measured, and its result is referring to Fig. 3, and its deviation is less than 3% as can be seen.The ESEM shape appearance figure of microballoon is shown in Fig. 4.
Embodiment 2
Difference from Example 1 is:
With the Sn-Ag-Cu (Sn95.6% for preparing; Ag3.5%; Cu0.9%; fusing point is 218 ℃) alloy makes block the adding in the crucible 15; shower nozzle 10 is equipped with in airtight furnace chamber 6 bottoms; 15 square little spray orifices of 0.05mm are arranged on the shower nozzle 10, and shower nozzle 10 aspect ratios are 4, and protective gas is an argon gas in the collecting pipe 11; after the charging; airtight furnace chamber 6 upper ends are connected with air supply system, and control temperature controller 7 temperature heat alloy, are heated to 250 ℃; programming rate is 21 ℃/minute; keep described temperature after 25 minutes, open air valve 2, gas pressure is adjusted to 1.37895 * 10 5Pa, the described expulsion pressure mode that applies is an intermittent mode, injection cycle is 0.1s; At this moment the ejection of alloy microballoon is arranged at shower nozzle 10 places, and controlled pressure and temperature make its state that is consistent always.Bead has sprayed back power failure cooling, after the cooling, takes out microballoon, sieves measurement, and its sphere diameter is distributed between 400~500 μ m, and spherical circularity is good.
Described protective medium of the present invention also can be nitrogen or organic media such as vegetable and animals oils, other mineral oil; The shape of spray orifice can also be triangle or polygon on the described shower nozzle 10.

Claims (6)

1. the preparation method of a microballoon scolder; it is characterized in that: adopt the micro-injection technology; in protective medium, use gases at high pressure the direct injection liquid metal or the alloy raw material of heat fused; the metal or alloy spherical solder of preparation narrow size distribution; be specially: the metal or alloy raw material is heated to more than the metal or alloy fusing point 5 ℃~50 ℃, and expulsion pressure is 6.89476 * 10 4Pa~5.51580 * 10 5Pa sprays liquid metal or alloy raw material, controlled pressure and temperature-resistant in course of injection in protective medium; The injection diameter that adopts is φ 0.01~φ 0.8mm, is under 0.5~30 condition in shower nozzle aspect ratio excursion, obtains the metal or alloy spherical solder of narrow size distribution.
2. according to the preparation method of the described microballoon scolder of claim 1, it is characterized in that: the described expulsion pressure that applies can be continuous or intermittence, and the latter's injection cycle is 0.001~1s.
3. according to the preparation method of the described microballoon scolder of claim 1, it is characterized in that: described protective medium adopts Ar or N 2, perhaps adopt vegetable and animals oils or mineral oil.
4. used micro-spray device according to the described preparation method of claim 1, it is characterized in that: be installed on the support (13), mainly form by high-pressure air source, airtight furnace chamber (6), crucible (15), temperature controller (7), heating furnace (9), shower nozzle (10), collecting pipe (11), collecting box (14), wherein: the collecting pipe of sealing (11) is the workspace, inside is filled with protective medium, its first half outside is provided with heating furnace (9), and heating furnace (9) links to each other with temperature controller (7); Crucible (6) is positioned at airtight furnace chamber (6), and a shower nozzle (10) is equipped with in airtight furnace chamber (6) lower end, inserts in the collecting pipe (11), and airtight furnace chamber (6) upper end is connected with air supply system by gas conduit (4); Described shower nozzle has at least one spray orifice on (10); Described collecting pipe (11) lower end is provided with collecting box (14); Described metal or alloy raw material (8) is contained in the sealed crucible (6).
5. according to the described preparation method's of claim 4 used micro-spray device, it is characterized in that: described air supply system is made up of high-pressure air source (1), air valve (2), pressure controller (3), wherein high-pressure air source (1) is received pressure controller (3) by pipeline, and pipeline is provided with air valve (2); Expulsion pressure is 6.89476 * 10 4Pa~5.51580 * 10 5Pa.
6. according to the described preparation method's of claim 4 used micro-spray device, it is characterized in that: the diameter that described shower nozzle (10) is gone up spray orifice is φ 0.01~φ 0.8mm, and the spray orifice shape can be circular, square, triangle or polygon; The aspect ratio excursion of spray orifice is 0.5~30 in the shower nozzle (10).
CN 02132882 2002-09-06 2002-09-06 Method for preparing microshere solder and micro spraying device utilized Expired - Fee Related CN1220571C (en)

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CN1220571C true CN1220571C (en) 2005-09-28

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JP6106852B2 (en) * 2014-11-13 2017-04-05 パナソニックIpマネジメント株式会社 Nozzle head, metal particle manufacturing apparatus using the nozzle head, and metal particle manufacturing method
CN104959621A (en) * 2015-08-04 2015-10-07 广东先导稀材股份有限公司 Preparation method and device of metallic particle
CN113560587A (en) * 2021-08-12 2021-10-29 广州海普电子材料科技有限公司 BGA tin ball smelting and rapid forming method

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