JP2005347398A - Packaging substrate for solid-state image pickup device, camera module, and portable telephone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the connection section between a solid-state image pickup device and a packaging substrate from being damaged by the thermal expansion of the packaging substrate that occurs repeatedly. <P>SOLUTION: A connection terminal 33 of the solid-state image pickup device 20 is mounted to a land 47 in a rigid substrate 43 of the packaging substrate 22 by soldering. A plurality of grooves 48 along the width direction of the rigid substrate 43 are formed at a position opposite to the connection terminal 33 of the solid-state image pickup device 20 on the lower surface of the rigid substrate 43. When imaging is made by the solid-state image pickup device 20, the solid-state image pickup device 20 generates heat, and the heat is transmitted to the rigid substrate 43 through the connection terminal 33 and a land 47. Although the rigid substrate 43 is thermally expanded by the heat, the expansion is absorbed by the grooves 48 so that no loads are applied to the soldered section of the connection terminal 33 and the land 47. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mounting substrate for a solid-state imaging device, a camera module using the mounting substrate, and a mobile phone in which the camera module is incorporated, and more specifically, the solid-state imaging device is peeled off from the mounting substrate due to thermal expansion of the mounting substrate. The present invention relates to a mounting substrate, a camera module, and a mobile phone that are prevented from being performed.

  Mobile phones to which a photographing function is provided by incorporating a solid-state imaging device or the like are widespread. In order to make it easy to incorporate a photographing function into a small electronic device such as a cellular phone, a solid-state imaging device, an optical unit in which an imaging optical system is incorporated, and a mounting board provided with a control circuit are assembled. A unitized camera module is provided (see, for example, Patent Document 1).

  A conventional solid-state imaging device includes a bare chip in which a solid-state imaging element and connection terminals are formed on a semiconductor substrate made of silicon, a package that houses the bare chip, and a package that does not hinder light transmission to the solid-state imaging element. And a cover glass that closes the opening. The bare chip and the package are wired by bonding wires.

  As one of packaging methods for downsizing a semiconductor device, a wafer level chip size package (hereinafter abbreviated as WLCSP) is known. This solid-state imaging device using WLCSP (see, for example, Patent Document 2) includes a semiconductor substrate on which a solid-state imaging device and connection terminals are formed, and an adhesive on the semiconductor substrate so as to surround the solid-state imaging device. It is composed of a spacer to be attached and a cover glass for sealing the solid-state image sensor by covering the spacer, and is significantly reduced in size as compared with a solid-state image sensor using a conventional package.

  A camera module using the above-described WLCSP type solid-state imaging device has been filed in advance by the present applicant (Japanese Patent Application No. 2003-320271). In this camera module, the connection terminal of the mounting substrate is soldered to mount the solid-state imaging device, and the optical unit is made use of the high accuracy of the flatness of the cover glass and the parallelism of the semiconductor substrate and the cover glass. Is attached to the cover glass.

JP 2001-078064 A JP 2001-257334 A

  It is known that solid-state imaging devices generate heat when imaging. Further, silicon, which is a material for a semiconductor substrate, and glass epoxy, which is a material for a mounting substrate, have different thermal expansion coefficients. Therefore, when the solid-state imaging device generates heat due to imaging, the mounting substrate having a higher thermal expansion coefficient than silicon expands more than the solid-state imaging device, and a load is applied to the soldered portion between the mounting substrate and the semiconductor substrate. This thermal expansion occurs repeatedly due to the use / nonuse of the photographing function of the mobile phone, so that the soldered portion between the mounting substrate and the semiconductor substrate may be fatigued and the solid-state imaging device may be peeled off from the mounting substrate. It was.

  The present invention is for solving the above-described problems, and prevents damage to the connection portion between the solid-state imaging device and the mounting substrate due to repeated thermal expansion.

  The mounting substrate for a solid-state imaging device of the present invention is provided with a groove or hole for absorbing thermal expansion of the substrate on the back surface of the substrate. Further, the groove and the hole are provided in the vicinity of the connection terminal of the solid-state imaging device where the temperature increases.

  Further, in another embodiment, grooves and holes are provided at a predetermined pitch over the entire back surface of the substrate. In addition, this pitch is narrowed in the vicinity of the connection terminal of the solid-state imaging device where the temperature increases.

  Furthermore, the camera module and the mobile phone of the present invention prevent damage due to thermal expansion by using the mounting substrate for a solid-state imaging device.

  According to the present invention, since the thermal expansion of the mounting substrate is absorbed by the grooves and holes provided on the back surface, the load applied to the mounting portion between the solid-state imaging device and the mounting substrate can be reduced. It is possible to prevent peeling off from the mounting substrate. Also, the grooves and holes are arranged near the connection terminals of the solid-state imaging device where the temperature tends to be high, or the arrangement pitch is narrowed near the connection terminals of the solid-state imaging device, so the mounting board is more effective. The thermal expansion of can be absorbed. Furthermore, since the surface area of the mounting substrate is increased by the grooves and holes, the cooling efficiency of the mounting substrate and the solid-state imaging device can be increased.

  FIG. 1 is an external perspective view showing an open state of a foldable mobile phone. The cellular phone 2 includes a handset unit 3 and a handset unit 4, which are connected to each other by a hinge portion 5 so as to be foldable. The receiver unit 3 of the cellular phone 2 includes a received voice output unit 6 for outputting received voices, a display unit 7 for displaying various information, an imaging unit 8 for taking a picture, and a telescopic antenna 9. Is provided. The transmitter unit 4 is provided with first to n-th operation buttons 10 for operating the mobile phone 2 and a transmission voice input unit 11 for inputting a transmission voice.

  FIG. 2 is a cross-sectional view of the main part showing the configuration of the imaging unit 8 of the mobile phone 2. An imaging opening 15 is formed in the exterior cover 14 of the mobile phone 2. The opening 15 is closed by a protective plate 16 made of transparent plastic or the like. A camera module 19 fixed to the frame 17 of the mobile phone 2 with a plurality of screws 18 is disposed at a position facing the opening 15. As shown in FIG. 3, the camera module 19 includes a WLCSP type solid-state imaging device 20, an optical unit 21, and a mounting substrate 22.

  4 and 5 are a perspective view and a cross-sectional view of the main part showing the external shape of the solid-state imaging device 20. The solid-state imaging device 20 includes a semiconductor substrate 26, a frame-shaped spacer 27 bonded to the semiconductor substrate 26 with an adhesive 29, and a cover glass bonded on the spacer 27 to seal the inside of the spacer 27. 28.

  A solid-state image sensor 30 is provided on the upper surface of the semiconductor substrate 26. The solid-state image sensor 30 is composed of, for example, a large number of photodiodes and a CCD that transfers charges accumulated in these photodiodes. A color filter, a microlens, and the like are stacked on each photodiode.

  A plurality of connection terminals 33 are provided on the lower surface of the semiconductor substrate 26. These connection terminals 33 are made of a conductive material 35 filled in the through holes 34 of the semiconductor substrate 26, are connected to the upper surface of the semiconductor substrate 26, and are electrically connected to each CCD. An insulating layer 36 that insulates the semiconductor substrate 26 and the conductive material 35 from the inner wall of the through hole 34 and around the conductive material 35.

  The spacer 27 is made of an inorganic material such as silicon, and is formed in a square shape surrounding the solid-state imaging device 30. For the cover glass 28, transparent α-ray shielding glass is used in order to prevent destruction of each photodiode. The gap between the solid-state imaging device 30 and the cover glass 28 is provided so as not to reduce the light collecting ability of the microlens.

  The solid-state imaging device 20 is manufactured as follows, for example. First, silicon is laminated on a transparent glass substrate serving as a base material for the cover glass 28, and a large number of spacers 27 are formed on the glass substrate by using a photolithography technique, development, etching, or the like. Next, an adhesive 29 is applied to the end face of the spacer 27, and is bonded to a wafer on which a large number of solid-state image sensors 30, connection terminals 33, etc. are formed, whereby each solid-state image sensor 30 is bonded to the spacer 27 and the glass substrate. Seal with. Thereafter, when the glass substrate and the wafer are diced into individual pieces, a large number of solid-state imaging devices 20 are formed.

  The optical unit 21 includes a lens holder 39 and an imaging lens 40 incorporated in the lens holder 39. The lens holder 39 is made of, for example, plastic, and a cylindrical lens barrel portion 39a in which the imaging lens 40 is incorporated and a rectangular concave portion 39b continuous with the lower end of the lens barrel portion 39a are integrally formed. The recess 39b is fitted into the cover glass 28 of the solid-state imaging device 20, and is fixed on the cover glass 28 with an adhesive.

  The mounting substrate 22 is a rigid / flexible substrate including a rigid substrate 43 using a glass epoxy substrate, a ceramic substrate, or the like, and a flexible substrate 44 provided integrally with the rigid substrate 43. Although not shown in detail, a control IC that drives and controls the solid-state imaging device 20 and a memory that stores image data obtained by imaging are mounted on the flexible substrate 44. The control IC functions as an analog front end circuit in which, for example, an H driver (V driver), CDS, AGC, ADC, and the like are incorporated in one chip.

  An attachment space 46 in which the solid-state imaging device 20 is attached is provided on the upper surface of the rigid substrate 43. In this mounting space 46, a plurality of lands 47 to which the connection terminals 33 of the solid-state imaging device 20 are soldered are provided. A plurality of grooves 48 are formed along the short direction of the rigid substrate 43 at a position facing the land 47 on the lower surface of the rigid substrate 43. These grooves 48 absorb the thermal expansion of the rigid substrate 43 and improve the heat dissipation effect.

  When imaging is performed by the mobile phone 2, the solid-state imaging device 20 generates heat. The heat of the solid-state imaging device 20 is transmitted to the rigid substrate 43 through the connection terminals 33 and the electrode pads 47. Glass epoxy, which is the material of the rigid substrate 43, has a higher coefficient of thermal expansion than silicon, which is the material of the semiconductor substrate 26. Therefore, in the conventional camera module 19, a load is applied to the soldered portion between the solid-state imaging device 20 and the rigid substrate 43 due to the thermal expansion of the rigid substrate 43. There was something to do.

  However, in the mounting substrate 22 of the present invention, since the plurality of grooves 48 are formed on the lower surface of the rigid substrate 43 so as to face the land 47, the thermal expansion of the rigid substrate 43 can be absorbed by the grooves 48. Thereby, a load is not applied to the soldered portion between the solid-state imaging device 20 and the rigid substrate 43. Further, since the surface area of the lower surface of the rigid substrate 43 is increased by the groove 48, the heat dissipation effect of the rigid substrate 43 and the solid-state imaging device 20 is also improved.

  In the above embodiment, the groove 48 is formed only at the position of the rigid substrate 43 facing the connection terminal 33 of the solid-state imaging device 20, but the groove 51 is formed on the entire lower surface of the rigid substrate 50 as shown in FIG. It may be formed. According to this, the heat dissipation effect by the rigid substrate 50 can be further improved.

  Further, as shown in FIG. 7, a groove 56 can be formed in the entire area of the rigid substrate 55, and the pitch of the groove 56 can be narrowed at a portion facing the connection terminal 33. According to this, the strength reduction of the rigid substrate 55 due to the groove 56 can be suppressed while enhancing the heat dissipation effect.

  Moreover, in each said embodiment, although the groove | channel was arrange | positioned along the transversal direction of a rigid board | substrate, you may arrange | position along a longitudinal direction or may arrange | position in a grid | lattice form. Furthermore, in each of the above embodiments, the grooves are formed in the rigid substrate. However, as shown in FIG. 8, a plurality of holes 61 may be formed in the rigid substrate 60 to absorb the thermal expansion of the rigid substrate 60. The hole 61 may be a through hole or a non-through hole. Further, the hole 61 may be arranged only in the vicinity of the connection terminal of the solid-state imaging device, or may be provided in the entire area as shown in the figure. Further, when the holes 61 are provided in the entire area, the pitch in the vicinity of the connection terminals can be narrowed.

  Although the above embodiment has been described by taking a mobile phone as an example, the present invention can also be applied to a camera module incorporated in a digital camera and a camera module incorporated in another small electronic device.

It is a perspective view which shows the external appearance shape of the mobile telephone which implemented this invention. It is principal part sectional drawing of the imaging part vicinity of a mobile telephone. It is a disassembled perspective view which shows the structure of a camera module. It is a perspective view which shows the external appearance shape of a solid-state imaging device. It is principal part sectional drawing of a solid-state imaging device. It is principal part sectional drawing of the camera module using another embodiment. It is principal part sectional drawing of the camera module using another embodiment. It is a perspective view which shows the external appearance of the rigid board | substrate which formed the hole instead of the groove | channel.

Explanation of symbols

2 Mobile phone 8 Imaging unit 19 Camera module 20 Solid-state imaging device 21 Optical unit 22 Mounting substrate 26 Semiconductor substrate 33 Connection terminal 43 Rigid substrate 48 Groove

Claims (6)

A frame-shaped spacer that surrounds the solid-state image sensor is placed on a semiconductor substrate on which the solid-state image sensor is formed, and the spacer is sealed with a transparent plate. In a mounting substrate for a solid-state imaging device comprising a wiring pattern to be formed and a substrate on which the wiring pattern is formed,
A mounting substrate for a solid-state imaging device, wherein a groove or a hole for absorbing thermal expansion of the substrate is provided on the back surface of the substrate.   The mounting substrate for a solid-state imaging device according to claim 1, wherein the groove or hole is provided in the vicinity of a connection terminal of the solid-state imaging device connected to the wiring pattern.   2. The mounting substrate for a solid-state imaging device according to claim 1, wherein the grooves and holes are provided at a predetermined pitch over the entire back surface of the substrate.   4. The mounting substrate for a solid-state imaging device according to claim 3, wherein the pitch of the grooves and holes is narrowed in the vicinity of the connection terminal of the solid-state imaging device. A solid-state imaging device in which a frame-shaped spacer surrounding the solid-state imaging device is arranged on a semiconductor substrate on which the solid-state imaging device is formed, and the spacer is sealed with a transparent plate, and the solid-state imaging device is mounted. In a camera module comprising a mounting substrate and an optical unit mounted on the transparent plate and incorporating an imaging optical system that forms a subject image on a solid-state imaging device,
A camera module using the mounting substrate for a solid-state imaging device according to claim 1 as the mounting substrate. In a mobile phone comprising an imaging unit that images a subject and a data storage unit that stores image data obtained by imaging,
A cellular phone using the camera module according to claim 5 as the imaging unit.

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