GB2322234A - Method of mounting an optical device and mounting therefor - Google Patents

Method of mounting an optical device and mounting therefor Download PDF

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Publication number
GB2322234A
GB2322234A GB9802839A GB9802839A GB2322234A GB 2322234 A GB2322234 A GB 2322234A GB 9802839 A GB9802839 A GB 9802839A GB 9802839 A GB9802839 A GB 9802839A GB 2322234 A GB2322234 A GB 2322234A
Authority
GB
United Kingdom
Prior art keywords
optical device
pieces
laminate
mounting
metal
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.)
Withdrawn
Application number
GB9802839A
Other versions
GB9802839D0 (en
Inventor
Hiroshi Honmou
Isao Yoneda
Junichi Sasaki
Masataka Itoh
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.)
NEC Corp
Original Assignee
NEC Corp
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 NEC Corp filed Critical NEC Corp
Publication of GB9802839D0 publication Critical patent/GB9802839D0/en
Publication of GB2322234A publication Critical patent/GB2322234A/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/10—Bump connectors ; Manufacturing methods related thereto
    • H01L24/11—Manufacturing methods
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/02—Structural details or components not essential to laser action
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/02—Bonding areas; Manufacturing methods related thereto
    • H01L2224/04—Structure, shape, material or disposition of the bonding areas prior to the connecting process
    • H01L2224/05—Structure, shape, material or disposition of the bonding areas prior to the connecting process of an individual bonding area
    • H01L2224/0554—External layer
    • H01L2224/05599—Material
    • H01L2224/056—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
    • H01L2224/05638—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof the principal constituent melting at a temperature of greater than or equal to 950°C and less than 1550°C
    • H01L2224/05644—Gold [Au] as principal constituent
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/10—Bump connectors; Manufacturing methods related thereto
    • H01L2224/12—Structure, shape, material or disposition of the bump connectors prior to the connecting process
    • H01L2224/13—Structure, shape, material or disposition of the bump connectors prior to the connecting process of an individual bump connector
    • H01L2224/13001—Core members of the bump connector
    • H01L2224/13099—Material
    • 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
    • H01L2924/01—Chemical elements
    • H01L2924/01004—Beryllium [Be]
    • 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
    • H01L2924/01—Chemical elements
    • H01L2924/01033—Arsenic [As]
    • 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
    • H01L2924/01—Chemical elements
    • H01L2924/01079—Gold [Au]
    • 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
    • H01L2924/013—Alloys
    • H01L2924/014—Solder alloys
    • 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
    • H01L2924/10—Details of semiconductor or other solid state devices to be connected
    • H01L2924/11—Device type
    • H01L2924/12—Passive devices, e.g. 2 terminal devices
    • H01L2924/1204—Optical Diode
    • H01L2924/12041—LED
    • 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
    • H01L2924/10—Details of semiconductor or other solid state devices to be connected
    • H01L2924/11—Device type
    • H01L2924/12—Passive devices, e.g. 2 terminal devices
    • H01L2924/1204—Optical Diode
    • H01L2924/12042—LASER

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Computer Hardware Design (AREA)
  • Manufacturing & Machinery (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Led Device Packages (AREA)
  • Semiconductor Lasers (AREA)
  • Supply And Installment Of Electrical Components (AREA)
  • Wire Bonding (AREA)

Abstract

A method of mounting an optical device such as a semiconductor laser 8 includes the steps of punching a metal foil (3), e.g. of AuSn a fine punch. The punch repeatedly punches the metal foil to provide a plurality of pieces of metal foil 3a, smaller in diameter than a metal pad 5 on a substrate 4, which are stacked on the metal pad in the form of a laminate. After an optical device 8 having a metal pad 7 has been temporarily placed on top of the laminate, the laminate is melted to provide a fine bonding lump between the optical device 8 and the substrate.

Description

METHOD OF MOUNTING AN OPTICAL DEVICE AND MOUNTING THEREFOR The present invention relates to a method of mounting an optical device, and to a mounting therefor.
A method of more accurately mounting an optical device for use in, e.g., an optical module for optical communication to a substrate, will be described below, by way of example in illustration of the invention.
The range of optical communication is being extended in parallel with advances in the performance and function of active and passive devices, including not only semiconductor lasers, light emitting diodes, photodiodes and optical modulators, but also optical fibres, optical switches, optical isolators, and optical waveguides. For example, the application of optical communications to subscriber circuits is currently of interest, and is made more practicable by reducing the cost of modules which are loaded with optical devices. The use of an adjustment-free optical mounting which is capable of mounting an optical device to a substrate via a fine bonding element which is formed on a metal pad is attracting increasing attention as an effective cost reduction scheme. The use of an adjustment-free optical mounting allows an optical device to be located at a bonding position limited by the pad as a result of a self-alignment effect resulting from the surface tension of the element when melted.
The fine bonding element has a spherical configuration and is formed by punching a ribbon-like bonding metal foil using a fine punch and a die, while bonding a piece punched out from the foil to a metal pad formed on a substrate, and then melting the piece.
Japanese Patent Application No. 2-278088 describes a fine bonding element formed of reliable AuSn.
To implement the accurate positioning of an optical device based on the above self-alignment effect, it is preferable that the melted element between the pad of the substrate and the pad of the optical device be symmetrical with respect to the centres of the pads, and that the melted element be provided with a height and a diameter substantially equal to each other. To provide the element with a height substantially equal to its diameter, the metal foil may be punched by a sufficiently great amount. For example, the thickness of a foil ribbon, or the diameter of the punch, may be increased.
However, increasing the thickness of the ribbon increases the required punching strength and thereby requires the size of the punching device to be increased. Increasing the diameter of the punch is liable to result in a part of the metal foil having a greater diameter than the metal pad of the substrate and therefore protruding beyond the metal pad. In such a situation, if the optical device is temporarily placed on the above mentioned part of the metal foil, and then the part is melted, the part is liable to contact the portion of the optical device which extends beyond the pad. Because such a portion of the optical device is low in wettability, it causes the surface tension of the melted element to deteriorate and the element to deform. The resulting lump is then unlikely to be symmetrical with respect to the centres of the pads of the substrate and the optical device, resulting in the accurate positioning of the optical device being made difficult.
It is a feature of an arrangement to be described below by way of example in illustration of the present invention that an optical device is located at a preselected bonding position with accuracy.
A particular method of mounting an optical device to be described below by way of example in illustration of the present invention includes the steps of stacking a plurality of pieces of metal foil, each having a smaller diameter than a first metal pad formed on a substrate, on the first metal pad to a desired thickness, thereby to form a laminate, placing an optical device, having a second metal pad which is greater in diameter than the pieces of metal foil, on the laminate, and melting the laminate thereby to mount the optical device to the substrate via a bonding element formed by the laminate.
A feature of one method to be described below, by way of example in illustration of the invention, is that the plurality of pieces of metal foil in the stack forming a laminate on a metal pad are smaller in diameter than the metal pad.
Arrangements which are considered to be helpful in understanding the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figs. 1-5 are diagrammatic sectional side views of arrangements for use in illustrating a method of mounting an optical device.
Referring to Figs. 1-5, a method of mounting an optical device is shown and applied to the fabrication of a substrate for an optical device by way of example.
First, as shown in Fig. 1, 30 Rm thick bonding metal foil 3 in the form of a ribbon and formed of AuSn is inserted between a fine punch 1 and a die 2. The punch 1 has an outside diameter of 40 Am and is formed of supersteel.
The die 2 is of stainless steel and is formed with a hole having a diameter of 45 Wm. The centre of the punch 1 and the centre of the hole of the die 2 are aligned with the centre of a metal pad 5 positioned on a substrate 4 formed of Si. The metal pad 5 is formed of Au and has a diameter of 50 Cun greater than the diameter of the punch 1.
Subsequently, as shown in Fig. 2, the punch 1 is lowered to punch the metal foil 3. At the same time, the punch 1 bonds a piece 3a, which has been punched out from the foil 3, to the metal pad 5. The punch 1 is caused to repeat this action with the metal foil 3 being sequentially shifted. As a result, as shown in Fig. 3, a plurality of pieces 3a each having a smaller diameter than the metal pad 5 are sequentially stacked on the same metal pad 5 to a desired thickness, forming a laminate.
As shown in Fig. 4, a semiconductor laser or similar optical device 8 has a metal pad 7 of Au formed thereon, the pad 7 having a diameter, of e.g., 50 Rm, greater than the diameter of the pieces 3a. The optical device 8 is temporarily placed on the top piece 3a of the laminate.
While Figs. 3 and 4 show three pieces 3a laminated together, the number of pieces 3a is determined in accordance with the thickness of the metal foil 3 in order to implement a desired thickness. This forms a fine bonding element in the form of a bump or lump whose height and diameter are substantially equal between the pad 5 of the substrate 4 and the pad 7 of the optical device 8, as will be described hereinafter.
As shown in Fig. 5, the pieces 3a in the form of a laminate are melted by, e.g., the local application of a laser beam. Consequently, the pieces 3a are formed into a single fine element or bump or lump 6, whose height and diameter are substantially equal, between the pads 5 and 7. The element 6 is symmetrical with respect to the centres of the pads 5 and 7. This results in a sufficient self-alignment effect and accurately locates the optical device 8 at a bonding position limited by the electrode pad 5 of the substrate 4. The illustrative embodiment is capable of causing the optical device 8 to be positioned with an accuracy as high as 1 Zm or less, as determined by experiment. To melt the pieces 3a, the substrate 4 may be placed on a hot plate and heated thereby, if desired.
The optical device 8 is temporarily positioned before the melting of the pieces 3a in order not to reduce their wettability as a result of the oxidation of the pieces 3 at the time of melting.
In the above described embodiment, the metal foil 3 is a ribbon which is punched by the fine punch 1 and the die 2 in order to laminate the resulting pieces 3a.
Alternatively, a plurality of metal pieces may be formed beforehand and then laminated to a desired thickness. If desired, the single punch 1 may be replaced with a plurality of fine punches.
Further, the metal foil 3 formed of AuSn may be replaced with metal foil of PbSn, AuSi or similar material. However, from the self-alignment standpoint, the AuSn bump or lump is advantageous over, e.g., a PbSn bump or lump in that it reduces the dislocation of the optical device 8 ascribable to a solder creep phenomenon.
In summary, it will be understood that there has been described, by way of example an arrangement in which a plurality of pieces of metal foil, smaller in diameter than a metal pad provided on a substrate, and a metal pad provided on an optical device are laminated on the pad of the substrate. Such pieces, when melted, provide a fine bonding element having a desired thickness and having a height and a diameter substantially equal to each other.
That is, the fine lump or bump is achievable without increasing the thickness of the metal foil itself. This prevents the need for increasing the size of a punching device. Further, because the pieces of the metal foil do not protrude from the metal pad of the optical device, the lump, which formed between the pad of the substrate and the pad of the optical device, is symmetrical with respect to the centres of the two pads.
Moreover, the lump or bump having the above symmetrical configuration and the height and diameter substantially equal to each other provides a sufficient self-alignment effect. It follows that an optical device can be located with a high degree of accuracy at a position limited by the pad of the substrate.
It will be understood that, although particular arrangements have been described, by way of example in illustration of the present invention, variations and modifications thereof, as well as other embodiments, may be made within the scope of the protection sought by the appended claims.

Claims (10)

1. A method of mounting an optical device, including the steps of stacking a plurality of pieces of metal foil, each having a smaller diameter than a first metal pad formed on a substrate, on the first metal pad to a desired thickness thereby to form a laminate, placing an optical device formed with a second metal pad greater in diameter than the pieces of the laminate, and melting the laminate thereby to mount the optical device on the substrate via a resulting fine bonding element formed by the laminate.
2. A method as claimed in claim 1, wherein the pieces are formed of AuSn.
3. A method as claimed in claim 1, wherein the pieces are formed by repeatedly punching a metal foil ribbon using a fine punch which is smaller in diameter than the first and second metal pads and a die.
4. A method as claimed in claim 3, wherein the pieces are of AuSn.
5. A method as claimed in claim 1, wherein the desired thickness is that which provides the fine bonding element with a height and a diameter which are substantially equal to each other.
6. A method as claimed in claim 5, wherein the pieces are of AuSn.
7. A method of mounting an optical device to a metal pad formed on a substrate, including the steps of stacking a plurality of pieces of metal foil, which are smaller in diameter than the metal pad, on the metal pad thereby to form a laminate, and melting the laminate thereby to mount the optical device on the metal pad.
8. A mounting for an optical device upon a substrate, which includes a first metal pad on the substrate, a second metal pad on the optical device and a lump or bump between the first and second metal pads, the lump or bump including a plurality of pieces of metal foil, each piece having a diameter less than that of either one of the metal pads, arranged to form a laminate, and the laminate having been melted.
9. A method of mounting an optical device as claimed in claim 1 or claim 7 substantially as described herein with reference to the accompanying drawings.
10. A mounting as claimed in claim 8 made by a method substantially as described herein with reference to the accompanying drawings.
GB9802839A 1997-02-13 1998-02-10 Method of mounting an optical device and mounting therefor Withdrawn GB2322234A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP9029030A JPH10223690A (en) 1997-02-13 1997-02-13 Optical element mounting method

Publications (2)

Publication Number Publication Date
GB9802839D0 GB9802839D0 (en) 1998-04-08
GB2322234A true GB2322234A (en) 1998-08-19

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GB9802839A Withdrawn GB2322234A (en) 1997-02-13 1998-02-10 Method of mounting an optical device and mounting therefor

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GB (1) GB2322234A (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8790520B2 (en) * 2011-08-31 2014-07-29 Lexmark International, Inc. Die press process for manufacturing a Z-directed component for a printed circuit board

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4832255A (en) * 1988-07-25 1989-05-23 International Business Machines Corporation Precision solder transfer method and means
WO1992006491A1 (en) * 1990-10-09 1992-04-16 Eastman Kodak Company Bonding of solid state device to terminal board
US5275970A (en) * 1990-10-17 1994-01-04 Nec Corporation Method of forming bonding bumps by punching a metal ribbon
EP0622837A1 (en) * 1993-04-27 1994-11-02 Nec Corporation An optical semiconductor device and a method of manufacturing the same
WO1997019466A1 (en) * 1995-11-22 1997-05-29 Fry's Metals, Inc. Method and apparatus for forming solder bumps on a substrate

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4832255A (en) * 1988-07-25 1989-05-23 International Business Machines Corporation Precision solder transfer method and means
WO1992006491A1 (en) * 1990-10-09 1992-04-16 Eastman Kodak Company Bonding of solid state device to terminal board
US5275970A (en) * 1990-10-17 1994-01-04 Nec Corporation Method of forming bonding bumps by punching a metal ribbon
EP0622837A1 (en) * 1993-04-27 1994-11-02 Nec Corporation An optical semiconductor device and a method of manufacturing the same
WO1997019466A1 (en) * 1995-11-22 1997-05-29 Fry's Metals, Inc. Method and apparatus for forming solder bumps on a substrate

Also Published As

Publication number Publication date
GB9802839D0 (en) 1998-04-08
JPH10223690A (en) 1998-08-21

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