Source: http://www.google.com/patents/US6640436?dq=6948823
Timestamp: 2015-07-01 07:50:41
Document Index: 767689360

Matched Legal Cases: ['art 5', 'art 5', 'art 7', 'art 7', 'art 5', 'art 44', 'art 44']

Patent US6640436 - Method of fabricating a coated metallic wire, method of removing insulation ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA method for fabricating a semiconductor device includes removing a predetermined part of an insulative layer of a coated fine metallic wire by irradiating the predetermined part with a laser light and connecting the predetermined part of the fine metallic wire to one of the semiconductor device and...http://www.google.com/patents/US6640436?utm_source=gb-gplus-sharePatent US6640436 - Method of fabricating a coated metallic wire, method of removing insulation from the coated metallic wire and method of fabricating a semiconductor device with the wireAdvanced Patent SearchPublication numberUS6640436 B1Publication typeGrantApplication numberUS 09/664,717Publication dateNov 4, 2003Filing dateSep 19, 2000Priority dateOct 16, 1997Fee statusLapsedAlso published asCN1215214A, US6239376Publication number09664717, 664717, US 6640436 B1, US 6640436B1, US-B1-6640436, US6640436 B1, US6640436B1InventorsNaoto Kimura, Takahiro ItoOriginal AssigneeNec Electronics CorporationExport CitationBiBTeX, EndNote, RefManPatent Citations (25), Referenced by (7), Classifications (54), Legal Events (4) External Links: USPTO, USPTO Assignment, EspacenetMethod of fabricating a coated metallic wire, method of removing insulation from the coated metallic wire and method of fabricating a semiconductor device with the wire
US 6640436 B1Abstract
A method for fabricating a semiconductor device includes removing a predetermined part of an insulative layer of a coated fine metallic wire by irradiating the predetermined part with a laser light and connecting the predetermined part of the fine metallic wire to one of the semiconductor device and a package of the semiconductor device. The insulative layer contains a substance that absorbs the laser light at a predetermined lasing wavelength.
What is claimed is: 1. A method for fabricating semiconductor device comprising:
removing a predetermined part of an insulative layer of a coated fine metallic wire, by irradiating said predetermined part of said insulative layer with a laser light, said insulative layer containing a substance absorbing said laser light of a predetermined lasing wavelength; and connecting said fine metallic wire at said predetermined part to one of said semiconductor device and a package of said semiconductor device. 2. The method for fabricating a semiconductor device according to claim 1, wherein said laser light comprises ultraviolet laser light.
3. The method of claim 1, wherein said fine metallic wire comprises gold.
4. The method of claim 1, wherein said fine metallic wire comprises aluminum.
5. The method of claim 1, wherein said insulative layer comprises nylon resin containing about 15 weight percent of iron black pigment.
6. The method of claim 1, wherein said insulative layer comprises more than 3 but no more than 35 weight percent of pigment.
7. The method of claim 1, wherein said insulative layer comprises more than 3 but no more than 35 weight percent of dye.
8. The method of claim 7, wherein said dye comprises one of azo dye, anthraquinone dye, indigoid dye, diphenylmetane dye, tryphenylmetane dye, xanthene dye, acridine dye, azine dye, oxazine dye, thiazine dye, quinoline dye and phthalocyanine dye.
9. The method of claim 1, wherein said insulative layer comprises more than 3 but not more than 30 weight percent of carbonic impalpable powder.
10. The method of claim 9, wherein said carbonic impalpable powder comprises particles having a diameter of less than 1 μm.
11. The method of claim 1, wherein said insulative layer is formed directly on a surface of said fine metallic wire.
12. The method of claim 1, wherein the fine metallic wire is unharmed during said removing of said predetermined part of said insulative layer.
This application is a divisional of application Ser. No. 09/173,742 filed Oct. 16, 1998 now U.S. Pat. No. 6,239,376 issued May 29, 2001.
The invention relates to a coated fine metallic wire, and especially to a coated fine metallic wire to be used as a bonding wire in a semiconductor device and a method for fabricating a semiconductor device using the same.
A conventional coated fine metallic wire used as a bonding wire in a semiconductor device is composed of a fine metallic wire and an insulative layer formed therearound, and its exterior view is the same as that of a coated fine metallic wire according to the invention shown in FIG. 1.
As an example of the aforementioned coated fine metallic wire, that insulated by heat resisting epoxy resin is described in Japanese patent Kokai 7-268278. Moreover, in the above mentioned reference, polyurethane resin, nylon resin, polyimide resin, resin of fluorine series, polyethylene resin, poly vinyl chloride resin, enamel as varnish, polyester resin and heat resisting polyurethane resin are described as known material used for the same purpose.
Among the coated fine metallic wires covered with aforementioned known material, that covered with polyester is unsuited for bonding and failure in bonding is apprehended, for rigidity of polyester is too high. Heat resisting properties of polyester resin, polyimide resin, nylon resin and resin of fluorine series are high. However, each of these is not resolved, but carbonized by heating temperature at the time of bonding, especially in case that an end portion of the coated fine metallic wire is melted and formed into a metallic ball. Accordingly, a carbonized matter stuck to the coated wire or the metallic ball is caught by a capillary, and disturbs supply of the wire and bonding between the metallic ball and an electrode terminal. On the other hand, in order to bond the coated wire with a lead with high reliability, it is necessary to thermally remove the insulative layer at a bonding part of the coated wire on the side of the lead by means of discharge process, but a carbonized matter remains on the surface of the metallic wire, hence subsequent bonding cannot be carried out securing high reliability.
In heat resisting epoxy resin used as material of the insulative layer, uplift of heat resisting property, avoidance of occurrence of carbonized matter and improvement of reliability of bonding are intended. However, even in case of the coated fine metallic wire with the insulative layer formed of heat resisting epoxy resin, removal of the insulative layer is carried out by means of discharge process, so that it is difficult to remove the insulative layer without melting the fine metallic wire and securing stability.
Accordingly, it is an object of the invention to provide a coated fine metallic wire, in which an insulative layer can be certainly removed without melting a fine metallic wire and securing stability.
It is a further object of the invention to provide a method for fabricating a semiconductor device using a coated fine metallic wire, in which an insulative layer can be certainly removed without melting a fine metallic wire and securing high ntability.
According to the first feature of the invention, a covered fine metallic wire comprises:
a fine metallic wire, and
an insulative layer, which is formed around the fine metallic wire and absorbs a laser light of a predetermined laising wavelength with high efficiency.
According to the second feature of the invention, a method for fabricating a semiconductor device comprises:
removing a predetermined part of an insulative layer of a coated fine metallic wire, which contains substance absorbing a laser light of a predetermined lasing wavelength with high efficiency, by irradiating the predetermined part of the insulative layer with the laser light, and
connecting a fine metallic wire at the predetermined part with a semiconductor device or its package.
FIG. 1 shows a perspective view for schematically showing an exterior view of a coated fine metallic wire used as a bonding wire in a semiconductor device according to the invention,
FIG. 2 shows a perspective view for schematically showing the state that a part of an insulative layer of a coated fine metallic wire is removed,
FIG. 3 shows a cross-sectional view for schematically showing the state that a fine metallic wire formed of Au is used as a bonding wire in a semiconductor device, and
FIG. 4 shows a cross-sectional view for schematically showing the state that fine metallic wire formed of Al is used as a bonding wire in a semiconductor device.
Next, the embodiments of the invention will be explained in detail referring to the drawings. FIG. 1 shows a perspective view of a coated fine metallic wire used as a bonding wire in a semiconductor device schematically as the first preferred embodiment of the invention.
The coated fine metallic wire 1 according to the invention is produced by coating a fine metallic wire 2 formed of Au with an insulative layer 3 formed of nylon resin containing about 15 weight percent of iron black pigment.
FIG. 2 shows a perspective view for schematically showing the coated fine metallic wire 1, the insulative layer 3 of which is removed by irradiation of a laser light 4. The insulative layer 3 at the irradiated part 5 is removed by irradiation of the laser light 4 and the fine metallic wire 2 is exposed. As mentioned in the above, since the insulative layer 3 of the coated fine metallic wire 1 according to the invention is formed of nylon resin containing about 15 weight percent of iron plack pigment, the insulative layer 3 absorbs the laser light 4 with high efficiency, and only the insulative layer 3 at the irradiated part 5 is perfectly removed without hurting the fine metallic wire 2.
Next, a method for fabricating a semiconductor device comprising the coated fine metallic wire 1 will be explained referring to the drawings as the second preferred embodiment of the invention.
FIG. 3 shows a cross-sectional view for schematically showing the state of a coated fine metallic wire used as a bonding wire in a semiconductor device. After an end of the coated fine metallic wire 1 is bonded with a pad 12 of a chip 11, which is adhered to an island 14 of a lead frame (or a package) by adhesive 13 such as silver paste, another and thereof is bonded with a lead 15.
Explaining concretely, discharge process is applied to a part near an end of the coated fine metallic wire 1 on the side of the pad 12, the insulative layer 3 is removed, and an Au wire 2 is melted to form a ball 6, which is bonded with the pad 12 by thermal compression bonding. On the other hand, near another end of the coated fine metallic wire 1 on the side of a lead 15, the insulative layer 3 at a bonding part 7 is irradiated by a laser light 4 so that the insulative layer 3 corresponding thereto is perfectly removed. Thereafter, the bonding part 7 of the covered fine metallic wire 1 is bonded with the lead 15 by thermal compression bonding.
FIG. 4 shows a cross-sectional view for schematically showing the state of bonding in the semiconductor device for case that a fine metallic wire 42 of the coated fine metallic wire 41 is formed of Al. In this case, since it is impossible to form the coated insulative wire 41 into a ball by discharge process on the side of the pad 12, the insulative layer 43 is irradiated by the laser light 4 at the irradiated part 5 corresponding to a ultra sonic bonding part 44 so that the insulative layer 43 thereon is perfectly removed. Thereafter, the ultra sonic bonding part 44 of the coated fine metallic wire 41 is bonded with the pad 12 by ultra sonic bonding process. Since bonding on the side of the lead 46 is the same as that shown in FIG. 3, an explanation thereon will be omitted.
As mentioned in the above, according to the method for fabricating the semiconductor device according to the embodiment of the invention, since the insulative layer of the coated fine metallic wire can be removed without hurting the fine metallic wire by means of laser irradiation, more stable bonding becomes possible.
Especially, in case that the insulative layer contains pigment or dye of a suitable percentage, since the insulative layer aborbs the laser light with high efficiency, the effect is noticeable.
Moreover, in case that an ultraviolet laser is used, the laser light absorption is concentrated in the vicinity of the surface of the insulative layer, the effect is still more noticeable.
Furthermore, the kinds and the percentage of content of carbonic impalpable powder, pigment or dye contained in the insulative layer can be suitably selected in accordance with the basic material of the insulative layer and the condition of coating (such as thickness of the insulative layer). The lasing wavelength and the output power of the laser light for removing the insulative layer can be suitably selected in consideration of basic material of the insualtive layer, the condition of coating, the kinds and percentage of content of carbonic impalpable powder, pigment and dye.
According to the coated fine metallic wire for bonding in the semiconductor device according to the invention, since its insulative layer contains pigment or dye, the laser light is absorbed by the insulative layer with high efficiency, only the insulative layer at the irradiated part can be removed, and therefore stable bonding can be realized.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS3930104Oct 21, 1974Dec 30, 1975Gen ElectricFlame-resistant polyolefin used as insulator for electrical conductorsUS3941866Jul 31, 1973Mar 2, 1976Colorguard CorporationMethod of bonding a thermoplastic resinous protective coating to a metallic substrateUS4085162Dec 8, 1975Apr 18, 1978General Electric CompanyPolyolefin with phosphorylated novolac and triallyl cyanurateUS4105825Jul 2, 1976Aug 8, 1978General Electric CompanyPolyolefin with phosphorylated novolac flame retardant, peroxide cured, as metallic insulatorUS4107370Feb 27, 1976Aug 15, 1978Ingraham Glen EThermoplastic resinous protective coating on a metallic substrateUS4182382Dec 1, 1975Jan 8, 1980Colorguard CorporationThermoplastic resin-coated metallic substrate and the method of producing the same through use of a polyamide adhesive layerUS4200973Aug 10, 1978May 6, 1980Samuel Moore And CompanyMethod of making self-temperature regulating electrical heating cableUS4237186Jul 28, 1978Dec 2, 1980Colorguard CorporationThermoplastic resin-coated metallic substrate and the method of producing the sameUS4361723Mar 16, 1981Nov 30, 1982Harvey Hubbell IncorporatedInsulated high voltage cablesUS4431982Jun 12, 1981Feb 14, 1984Dow Corning CorporationElectrically conductive polydiorganosiloxanesUS4607154Sep 26, 1983Aug 19, 1986Fieldcrest Mills, Inc.Electrical heating apparatus protected against an overheating condition and a temperature sensitive electrical sensor for use therewithUS4671848 *Dec 17, 1984Jun 9, 1987General Laser, Inc.Method for laser-induced removal of a surface coatingUS4970488Feb 17, 1989Nov 13, 1990Yazaki CorporationNoise-suppressing high voltage cable and method of manufacturing thereofUS4998002 *Jan 26, 1988Mar 5, 1991Hitachi, Ltd.Wire-bonding method, wire-bonding apparatus, and semiconductor device produced by the wire-bonding methodUS5074313Apr 20, 1990Dec 24, 1991Cardiac Pacemakers, Inc.Porous electrode with enhanced reactive surfaceUS5176310 *Feb 18, 1992Jan 5, 1993Hitachi, Ltd.Method and apparatus for wire bondUS5935465 *Nov 5, 1996Aug 10, 1999Intermedics Inc.Method of making implantable lead including laser wire strippingUS6218728 *Oct 26, 1998Apr 17, 2001Nec CorporationMold-BGA-type semiconductor device and method for making the sameUS6374488 *Jan 5, 2000Apr 23, 2002Intermedics Inc.Method of laser stripping coated cables for endocardial defibrillation leadsEP0355955A2 *Jun 12, 1989Feb 28, 1990Hitachi, Ltd.Connection for semiconductor devices or integrated circuits by coated wires and method of manufacturing the sameJPH0217813A * Title not availableJPH0955395A Title not availableJPH02266541A Title not availableJPH05343461A Title not availableJPH08118051A * Title not available* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS7067765Aug 23, 2004Jun 27, 2006Medtronic, Inc.Methods for forming electrically active surfaces for medical electrical leadsUS7086148 *Feb 25, 2004Aug 8, 2006Agere Systems Inc.Methods and apparatus for wire bonding with wire length adjustment in an integrated circuitUS7443042 *Mar 21, 2006Oct 28, 2008Agere Systems Inc.Methods and apparatus for wire bonding with wire length adjustment in an integrated circuitUS8076612 *Jan 24, 2006Dec 13, 2011Jumatech GmbhMethod for the continuous laying of a conductor on a printed circuit board and device for carrying out said methodUS8850702 *May 24, 2010Oct 7, 2014Cardiac Pacemakers, Inc.Cable consolidation with a laserUS20090095723 *Sep 25, 2008Apr 16, 2009Sumitomo Electric Industries, Ltd.Laser processing methodUS20100299921 *May 24, 2010Dec 2, 2010Hall Peter CCable Consolidation with a Laser* Cited by examinerClassifications U.S. Classification29/867, 29/864, 257/E21.518, 219/121.85, 29/857, 219/121.69, 29/825, 257/E23.025International ClassificationH01L21/60, H02G1/12, B23K26/18, H01B7/38Cooperative ClassificationH01L2224/48624, H01L2224/48724, H01L2224/48472, H01L24/48, H01L2924/0103, H01L2924/01006, H01L2924/01005, H01L2224/48247, H01L2924/01047, H01L2924/01033, H01L2924/01029, H01L2224/4556, H01L24/45, H01L2224/85201, H01L2924/01082, H01L2924/01022, H01L2224/4586, H01L24/85, H01L2224/45124, H01L2224/48227, H01L2224/45144, H01L2224/48465, H01L2224/05624, H01L2224/4579, H01L2224/48091, H01L2224/85205, H01L2924/01079, H01L2224/32245, H01L2224/85214, H01L2224/45565, H01L2924/01013, H01B7/38, H01L2924/01004, H01L2224/73265, H01L2924/01027, H01L2224/4569, H01L2224/45147, H01L2224/48799European ClassificationH01L24/45, H01L24/48, H01L24/85, H01B7/38Legal EventsDateCodeEventDescriptionFeb 27, 2003ASAssignmentOwner name: NEC ELECTRONICS CORPORATION, JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:NEC CORPORATION;REEL/FRAME:013796/0242Effective date: 20021101Owner name: NEC ELECTRONICS CORPORATION 1753 SHIMONUMABE NAKAHOwner name: NEC ELECTRONICS CORPORATION 1753 SHIMONUMABE NAKAHFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:NEC CORPORATION;REEL/FRAME:013796/0242Effective date: 20021101May 23, 2007REMIMaintenance fee reminder mailedNov 4, 2007LAPSLapse for failure to pay maintenance feesDec 25, 2007FPExpired due to failure to pay maintenance feeEffective date: 20071104RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services