JP2005353637A - Optical module and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module with stable output and an electronic device equipped with the optical module without being deteriorated by moisture absorption even in an environment where the optical element is high in humidity.
Since the surface emitting laser 3 is hermetically sealed by the moisture-resistant package 4 and the substrate 2, the surface emitting laser 3 is not exposed to the outside air even when the optical module 1 is under high humidity. Moisture contained in the outside air is blocked and does not enter the package 4. Thereby, the surface emitting laser 3 does not deteriorate due to moisture absorption, and the moisture resistance of the surface emitting laser 3 can be ensured.
[Selection] Figure 1

Description

  The present invention relates to an optical module in which an optical element is mounted on a wiring board, and an electronic device in which the optical module is mounted.

  As one method for mounting an optical element such as a semiconductor laser at a low temperature and a low load on a substrate on which electrical wiring is formed, the optical incident surface or light emission surface of the optical element is mounted and mounted on the substrate via a conductor bump. A method is known (flip chip mounting). An underfill agent such as a resin is filled between the light incident surface and the light emitting surface of the flip chip mounted optical element and the substrate, and the light incident surface and the light emitting surface are coated (for example, , See Patent Document 1).

The optical element mounted in this way is required to operate normally even in a high temperature and high humidity environment with a temperature of 85 ° C. and a humidity of 85%, for example.
JP 2004-86157 A

  However, in the environment of high temperature and high humidity as described above, the optical element absorbs moisture inside, so-called moisture absorption occurs only by coating with the underfill agent. Moisture absorbed and permeated into the interior deteriorates the optical element, causing problems such as the intensity of light emitted from the optical element becoming unstable. For this reason, the reliability of an optical element will be impaired.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical module having a stable output without deterioration due to moisture absorption even when the optical element is in a high humidity environment, and the optical module. To provide electronic equipment.

  In order to achieve the above object, an optical module according to the present invention includes a substrate and an optical element mounted on the substrate such that an incident surface for entering light or an exit surface for emitting light faces the substrate. An optical module, wherein the optical element is hermetically sealed by a package having moisture resistance and the substrate.

Here, “having moisture resistance” means blocking moisture and preventing moisture from entering.
According to the present invention, since the optical element is hermetically sealed by the moisture-resistant package and the substrate, the optical element is not exposed to the outside air even when the optical module is under high humidity, and the moisture contained in the outside air Is blocked and does not penetrate into the package. Thereby, the optical element does not deteriorate due to moisture absorption, and the moisture resistance of the optical element can be ensured.

  In the optical module according to the present invention, it is preferable that a semiconductor element for driving the optical element is enclosed in the package. In the present invention, for example, a semiconductor element can be mounted in advance in a package. In this case, since the wiring for electrically connecting the semiconductor element and the optical element can be formed inside the package, it is not necessary to mount the semiconductor element on the substrate, and the wiring formed on the substrate is reduced. can do. In addition, since the semiconductor element and the optical element can be provided close to each other, a wiring connecting the semiconductor element and the optical element can be formed short. Therefore, the wiring can be easily formed and the electric resistance due to the wiring can be kept low. In the present invention, the semiconductor element and the optical element can be mounted side by side on the substrate and sealed together. Thereby, since the semiconductor element and the wiring are also sealed, it is possible to prevent the semiconductor element and the wiring from being deteriorated by moisture.

  In the optical module according to the present invention, the optical element is preferably mounted on the substrate via a resin having conductivity or a resin mixed with conductive particles. Thereby, it is possible to mount an optical element reliably. In addition, since the above-described package and substrate seal the optical element at the same time as the resin used for mounting the optical element on the substrate, these resins may deteriorate due to moisture. Can be prevented. For example, when an anisotropic conductive film (ACF) or anisotropic conductive paste (ACP) is used, the electrical connection between the optical element and the substrate and the underfill agent are used. It becomes possible to share the sealing.

  In the optical module according to the present invention, it is preferable that the substrate is formed using a material having transparency to at least incident light or emitted light of the optical element. Thereby, the light emitted from the optical element or the incident light from the outside to the optical element can be transmitted through the substrate. Therefore, it is preferable to use a material having a high light transmittance for this substrate.

  In the optical module according to the present invention, the optical element is preferably a semiconductor laser. Examples of the optical element used in the present invention include a light receiving element such as a photodiode in addition to a light emitting element such as a semiconductor laser (including a surface emitting laser). Further, the present invention can of course be applied even when a light emitting element and a light receiving element are used in combination or when a plurality of light receiving elements are used.

  In the optical module according to the present invention, the refraction between the incident surface or the exit surface and the substrate is at least transparent to the incident light or the exit light and is substantially equal to the refractive index of the substrate. It is preferable that the material which has a rate is filled. Thereby, when light transmits between the incident surface or the exit surface and the substrate, the transmission loss can be suppressed. In addition, since the package and the substrate also seal the underfill agent that fills the entrance surface or the exit surface in the same manner as the optical element and the resin, the underfill agent is also prevented from being deteriorated by moisture. You can also. In this case, for example, if the transmittance and refractive index are desired values, even a material with low moisture resistance can be adopted as an underfill agent, that is, a wide selection of materials for the underfill agent can be selected. It becomes.

  In the optical module according to the present invention, the substrate is preferably formed using glass or polyimide. Since glass or polyimide has high light transmittance, loss when light passes through the substrate can be suppressed.

  In the optical module according to the present invention, the package is preferably formed using metal or ceramic. Metals and ceramics are particularly prominent in their ability to block moisture and prevent moisture from penetrating, so that moisture can be prevented from penetrating into the package. Some metals are oxidized and corroded and deteriorated by water, but it is possible to prevent such corrosion and deterioration by, for example, pre-oxidizing the surface exposed to the outside air. Therefore, the present invention can be sufficiently applied to the present invention.

  In the optical module according to the present invention, the contact portion between the package and the substrate is preferably sealed using solder or glass. According to the present invention, it is possible to prevent moisture from entering from the contact portion between the package and the substrate. Since solder or glass used for sealing the contact portion has higher moisture resistance than, for example, resin, it is possible to prevent moisture from entering more effectively. About glass, you may use low melting glass, for example.

  An electronic apparatus according to the present invention preferably includes the above optical module. According to the present invention, since the optical element is not deteriorated by moisture absorption even in a high humidity environment, a high-quality electronic device in which the output from the optical element is stable can be obtained.

Embodiments of an optical module according to the present invention will be described below with reference to the drawings. In the following drawings, the scale is appropriately changed to make each member a recognizable size.
FIG. 1 is a cross-sectional view schematically showing an overall configuration of an optical module 1 according to the present embodiment.
The optical module 1 includes a substrate 2 between a substrate 2 having a wiring and the like formed on the surface, a surface emitting laser 3 mounted so that a laser beam emission surface 5 a faces the substrate 2, and the substrate 2. And a package 4 that seals the surface emitting laser 3.
FIG. 2 is a diagram showing the configuration of the surface emitting laser 3 in more detail, and FIG. 3 is a diagram of the surface emitting laser shown in FIG. 2 as viewed from below. In FIG. 2, description will be made assuming that the multilayer film reflecting mirror 3b side is the upper side and the 3c side is the lower side.

  The surface emitting laser 3 has, for example, a three-stage structure including an active layer 3a and multilayer reflectors 3b and 3c provided above and below the active layer 3a. The surface emitting laser 3 is viewed from the exit surface 5a side. The vertical length t1 and the horizontal length t2 are about 300 to 500 μm, the thickness h1 of the surface emitting laser 3 is about 250 to 350 μm, and the height h2 from the lower surface 3d of the semiconductor laser 3 to the surface 2a of the substrate 2 Is about 30 μm. The active layer 3a is formed of a semiconductor such as gallium arsenide, for example, and laser light is generated by converting electric energy into light energy. Each of the multilayer-film reflective mirrors 3b and 3c has a multilayer structure in which materials having different refractive indexes are alternately stacked, and a laser beam generated in the active layer 3a is amplified. In the central portion of the surface emitting laser 3, for example, the lower surface 3 d, an emission port 5 that emits laser light generated in the active layer 3 a toward the substrate 2 is formed. In addition, a plurality of bumps 6, for example, six bumps 6 are provided on the lower surface 3 d so that an external electric signal is supplied to the surface emitting laser 3, and three bumps 6 are arranged in two rows with the injection port 5 in between (3). FIG. 3).

  Returning to FIG. 1, the configuration of the substrate 2 will be described. The substrate 2 is formed of a material having high transparency with respect to the laser light emitted from the surface emitting laser 3, such as glass or polyimide. On the surface 2a of the substrate 2, a semiconductor element (not shown) for driving the surface emitting laser 3, a plurality of pad terminals 8 for electrical connection with each bump 6 of the surface emitting laser 3, a semiconductor element and each A wiring (not shown) for electrically connecting the pad terminal 8 is formed. The semiconductor element is an IC chip formed of, for example, silicon, and a driving circuit for driving the surface emitting laser 3 is formed on the semiconductor element. Six pad terminals 8 are provided so as to correspond to the arrangement of the bumps 6 and are arranged in 3 × 2 rows. The wiring is made of, for example, copper or ITO (Indium Tin Oxide). On the back surface 2b side of the substrate 2, an optical waveguide 10 that conducts laser light from the surface emitting laser 3 to the outside is formed in a cylindrical shape, for example. In the optical waveguide 10, a core portion having a high refractive index is formed on a cylindrical core portion, and a cladding portion having a low refractive index is formed around the core portion. As a material for forming the core part and the clad part, for example, polyimide or photonic crystal is used.

  The pad terminal 8 and the bump 6 are electrically connected through a resin 12 containing conductive particles 11. As the material of the conductive particles 11, for example, a conductive material such as a metal such as silver, gold, copper, nickel, or carbon is used. As the resin 12, for example, a photo-curing resin that is cross-linked and cured by receiving ultraviolet (UV) or electron beam (EB) irradiation, or a thermo-setting resin that is cross-linked and cured by receiving heat is used. For example, monofunctional acrylates, polyfunctional acrylates, epoxy acrylates, urethane acrylates, etc. are used as monomer type resins, and polyester acrylates, polyether acrylates, reactive polyacrylates, carboxyl-modified reactive types are used as oligomer type resins. Polyacrylate, polybutadiene acrylate, silicon acrylate, aminoplast resin acrylate and the like are used. In the case of using a photocurable resin as the resin 12, it is preferable to have sufficient light transmittance so that light irradiated in the curing reaction reaches the entire resin. In addition, about resin 12 containing the electroconductive particle 11, for example, well-known anisotropic conductive resin (Anisotropic Conductive Past; ACP) can also be used as it is. As described above, the surface emitting laser 3 is fixed and mounted on the substrate 2 so as to be electrically connected to the semiconductor element via the conductive particles 11, the pad terminals 8 and the wiring.

  Since only the resin 12 formed in the vicinity of the pad terminal 8 and the bump 6 cannot be filled up to the vicinity of the exit 5, there is no space between the exit 5 of the surface emitting laser 3 and the substrate 2 (the portion that becomes the optical path of the laser light). The underfill agent 13 is filled. For the underfill agent 13, a photocurable resin or a thermosetting resin is used. In this case, since the underfill agent 13 is filled in the optical path of the laser beam, it is preferable to use a material having a particularly high light transmittance, and it is more preferable to use a non-filler type material that does not diffuse the laser beam. preferable. Further, in order to suppress transmission loss when laser light is incident on the substrate 2 from the underfill agent 13, it is more preferable to use a material having a refractive index substantially the same as the refractive index of the substrate 2.

FIG. 4 is a perspective view schematically showing the configuration of the package 4.
The package 4 is formed of a moisture-resistant material, for example, a metal such as stainless steel, ceramic, or the like, and has a bowl shape having an accommodating portion 4c surrounded by a side portion 4a and a bottom portion 4b. Here, “having moisture resistance” means blocking moisture and preventing moisture from entering. The size of the accommodating portion 4c is set such that the vertical length T1 and the horizontal length T2 of the accommodating portion are 300 to 500 μm and the depth, for example, in accordance with the size of the surface emitting laser 3 so that the surface emitting laser 3 is perfectly accommodated. The height H may be 280 to 380 μm, and within a range that does not hinder downsizing and weight reduction of the optical module 1, for example, the accommodating portion 4 c is slightly larger than the size of the surface emitting laser 3 so as to be easily aligned. In this way, the values of T1, T2, and T3 may be set. The thickness of the side part 4a of the package 4 is 50 μm or more, and the thickness of the bottom part 4b is 50 μm or more.

  As shown in FIG. 1, the package 4 is disposed so as to cover the surface emitting laser 3, that is, the surface emitting laser 3, the resin 12, the underfill agent 13, and the like are accommodated in the accommodating portion 4c. Further, the mouth portion 4d is brought into contact with the substrate 2, and the adhesive member 14 is applied to the contact portion between the substrate 2 and the mouth portion 4d to be adhered and fixed to the substrate 2. In order to prevent moisture and moisture from permeating through the gap between the substrate 2 and the mouth portion 4d, for example, a material having higher moisture resistance than resin or the like, for example, solder or low-melting glass is used for the adhesive member 14. In this way, the surface emitting laser 3, the resin 12, the underfill agent 13, and the like are hermetically sealed by the package 4, the substrate 2, and the adhesive member 14.

  According to the present embodiment, the surface emitting laser 3 is hermetically sealed by the moisture-resistant package 4 and the substrate 2, so that the surface emitting laser 3 is exposed to the outside air even when the optical module 1 is under high humidity. In other words, moisture contained in the outside air is blocked and does not enter the package 4. Thereby, the surface emitting laser 3 does not deteriorate due to moisture absorption, and the moisture resistance of the surface emitting laser 3 can be ensured. In addition, since the surface emitting laser 3 is covered with the package 4 and the adhesive member 14 is applied to the contact portion between the substrate 2 and the mouth portion 4d, the package 4 can be easily installed.

(Second Embodiment)
Hereinafter, a second embodiment of the optical module according to the present invention will be described. Similar to the first embodiment, in the following drawings, the scale is appropriately changed to make each member a recognizable size. Moreover, about the component same as 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted. This embodiment is greatly different from the first embodiment in that both the semiconductor element and the surface emitting laser 3 are sealed in the package 4.

FIG. 5 is a cross-sectional view schematically showing the configuration of the optical module 201 according to this embodiment.
The optical module 201 includes a substrate 2 having a wiring or the like formed on the surface thereof, a surface emitting laser 3 mounted so that a laser beam emission surface faces the substrate 2, and the substrate 2. And the package 4 that seals the surface emitting laser 3 and the semiconductor element 15, and the semiconductor element 15 for driving the surface emitting laser 3 that is mounted in advance on the bottom 4 b of the package 4.

  In the optical module 201, bumps 16 are formed on the semiconductor element 15. In particular, when the package 4 is made of a conductive material, the inside of the side part 4a and the bottom part 4b of the package 4 is covered with, for example, an insulating film (not shown), and the inside of the bottom part 4b Pad terminals (not shown) are formed on the insulating film. The bumps 16 and the pad terminals are electrically connected through, for example, a resin 12 containing conductive particles 11, and the semiconductor element 15 is mounted on the package 4 by the resin 12. Wiring (not shown) for electrically connecting the pad terminal to the pad terminal 8 is formed on the insulating film inside the side portion 4a of the package 4 and the substrate 2.

  As described above, since the semiconductor element 15 is mounted in the package 4 in advance, it is not necessary to mount the semiconductor element 15 on the substrate 2. In addition, since the wiring for electrically connecting the semiconductor element 15 and the surface emitting laser 3 is formed inside the package 4, the wiring formed on the substrate 2 can be reduced. Therefore, the wiring can be easily formed and the electric resistance due to the wiring can be kept low. Further, since the semiconductor element 15 and the wiring are also sealed, the semiconductor element 15 and the wiring can be prevented from being deteriorated by moisture.

FIG. 6 is a cross-sectional view schematically showing the configuration of another optical module 301 according to this embodiment.
The optical module 301 includes a substrate 2 having a wiring or the like formed on the surface thereof, a surface emitting laser 3 mounted so that a laser light emission surface faces the substrate 2 toward the substrate 2, and the surface emitting laser. A semiconductor element 15 for driving the surface emitting laser 3 mounted adjacently and a package 4 for sealing the surface emitting laser 3 and the semiconductor element 15 between the substrate 2 and the substrate 2 are provided.

  In the optical module 301, bumps 16 are formed on the semiconductor element 15. In addition, pad terminals (not shown) are formed on the substrate 2. The pad terminal and the bump 16 are electrically connected via a resin 12 containing conductive particles 11, and the semiconductor element 15 is mounted on the substrate 2 by the resin 12. On the substrate 2, wiring (not shown) for electrically connecting the pad terminal to the pad terminal 8 is formed.

  As described above, since the semiconductor element 15 is mounted adjacent to the surface emitting laser 3, the wiring for electrically connecting the surface emitting laser 3 and the semiconductor element 15 can be formed short. Therefore, the wiring can be easily formed and the electric resistance due to the wiring can be kept low. Further, since the semiconductor element 15 and the wiring are also sealed, the semiconductor element 15 and the wiring can be prevented from being deteriorated by moisture.

(Electronics)
Next, as an electronic apparatus provided with the optical modules 1, 201, and 301 of the above embodiment, a mobile phone will be described as an example.
FIG. 7 is a perspective view showing an example of a mobile phone. In FIG. 7, reference numeral 1000 indicates a mobile phone body provided with the optical modules 1, 201, and 301 described above, and reference numeral 1001 indicates a display unit. Here, the optical modules 1, 201 and 301 are used as optical signal output means in the mobile phone main body 1000.

  The optical modules 1, 201, and 301 according to the above embodiment can be applied to various electronic devices other than those described with reference to FIG. For example, optical fiber communication module, laser printer, laser beam projector, laser beam scanner, linear encoder, rotary encoder, displacement sensor, pressure sensor, gas sensor, blood blood flow sensor, fingerprint sensor, high-speed electrical modulation circuit, wireless RF circuit, mobile phone It can also be applied to telephones, wireless LANs, and the like.

  By mounting the above-described optical modules 1, 201, and 301 on an electronic device, even if the surface emitting laser 3 is in a high humidity environment, the surface emitting laser 3 does not deteriorate due to moisture absorption, so that the output from the surface emitting laser 3 is stable. High quality electronic equipment can be obtained.

Note that the technical scope of the present invention is not limited to the above-described embodiment, and modifications can be made as appropriate without departing from the spirit of the present invention.
For example, in the above-described embodiment, the optical modules 1, 201, and 301 are described as the optical elements mounted on the substrate 2, but the present invention can be applied even when, for example, a photodiode that is a light receiving element is used. Application is possible.

It is sectional drawing which shows the structure of the optical module which concerns on this invention. It is sectional drawing which shows the structure of a surface emitting laser. It is a bottom view which shows the structure of a surface emitting laser. It is a perspective view which shows the structure of a package. It is sectional drawing which shows the structure of the optical module which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows another structure of the optical module which concerns on 2nd Embodiment of this invention. It is a perspective view which shows the electronic device (cellular phone) which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 201, 301 ... Optical module 2 ... Board | substrate 3 ... Surface emitting laser 4 ... Package 4d ... Mouth part 8 ... Pad terminal 11 ... Conductive particle 12 ... Resin 13 ... Underfill agent 14 ... Adhesive member 15 ... Semiconductor element 16 ... Bump 1000 ... Mobile phone body 1100 ... Clock body

Claims (10)

An optical module comprising a substrate and an optical element mounted on the substrate such that an incident surface for entering light or an exit surface for emitting light faces the substrate,
An optical module, wherein the optical element is hermetically sealed with a package having moisture resistance and the substrate.   The optical module according to claim 1, wherein a semiconductor element that drives the optical element is enclosed in the package.   The optical module according to claim 1, wherein the optical element is mounted on the substrate via a resin having conductivity or a resin mixed with conductive particles.   The light according to any one of claims 1 to 3, wherein the substrate is formed using a material that is transparent to at least incident light or emitted light of the optical element. module.   A space between the incident surface or the exit surface and the substrate is filled with a material that is at least transparent to the incident light or the emitted light and has a refractive index substantially equal to the refractive index of the substrate. The optical module according to any one of claims 1 to 4, wherein   The optical module according to any one of claims 1 to 5, wherein the optical element is a semiconductor laser.   The optical module according to any one of claims 1 to 6, wherein the substrate is formed using glass or polyimide.   The optical module according to claim 1, wherein the package is formed using metal or ceramic.   9. The optical module according to claim 1, wherein a contact portion between the package and the substrate is sealed using solder or glass. An electronic apparatus comprising the optical module according to any one of claims 1 to 9.

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