JPS60247385A - Package sealing method of solid-state image pickup device - Google Patents

Abstract

PURPOSE:To seam and weld surely a lid and a package body without polluting the light-translucent lid by forming a brazing filler metal on a metallic frame for seam welding in the package body side and allowing a metallic material for seam welding, which is formed on a light-translucent thin plate, to face this brazing filler metal in the package body side to weld them. CONSTITUTION:A solder 20 is welded to the surface of a metallic frame 8 in the side of a package 2 before the metallic frame 8 is allowed to face a lid 9. This solder 20 is welded to the package-side metallic frame 8 in any stage before seam welding. A material obtained by heating and reflowing a pasty low-melting point metal after printing application on the metallic frame 8 may be used instead of the welded solder 20. The package-side metallic frame 8 to which the solder 20 is welded and a metallic frame 11 in the side of a lid 9 are allowed to face each other, and power is supplied to a welding electrode 16. The metallic frame 11 and the solder 20 are welded by heating due to the contact resistance, and thus, the side of the package 2 and the side of the lid 9 are adhered closely to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for sealing a cage that houses a solid-state image sensor. In the figure, a solid-state image sensor 1 is mounted on a package 2 made of laminated ceramic using an adhesive 3 such as Au-5i or Ag paste. A bonding pad on the solid-state image sensor 1 is connected to a bonding terminal on the package by an Au or At wire 4. This connection is connected to the external lead 5 via the internal wiring of the laminated ceramic package 2. A color filter array 6 for a color image sensor is attached onto the light receiving section of the solid-state image sensor 1 with an adhesive 7. However, the color filter array 6 and adhesive 7 are not used for monochrome imaging devices.

The solid-state imaging device 1 mounted on the package 2 is hermetically sealed to protect it from contamination, etc., or som welding has been conventionally used as the hermetic sealing method. Further, a ceramic frame 13 is bonded to the lithography via an adhesive glass layer 14, and the ceramic frame 1
3 is bonded to the metal frame 11 with a brazing material 12 interposed therebetween. The shapes of the lid metal frame 11 include the flat plate shape shown in FIG. 3, the drawn convex shape shown in FIG. 2, and the concave shape shown in FIG. 4. During seam welding for airtight sealing, a low melting point metal brazing material 10 such as Au-5n or Pb-5n is sandwiched between the upper and lower metal frames 8 and 11 in a sandwich-like manner.
Using the welding electrode +6i of the seam welding device, welded both metal frames 8 and 1.
A bond between 1 and 2 is made.

At this time, there are two welding interfaces, the first and second welding interfaces, that is, the first welding interface between the package upper metal frame 8 and the low melting point metal brazing filler metal 10, and the second welding interface between the low melting point metal brazing filler metal 10 and the lid upper metal frame 11. A welding interface is formed, and each welding interface generates heat due to contact resistance, melting the low melting point metal brazing filler metal 10, and forming the upper and lower metal frames 8.
, 11 minutes.

The advantage of the above sealing method is that heat generation only occurs during seam welding, so the solid-state image sensor 1, the curler filter array 6, the adhesive 7, etc. are subjected to only a slight thermal stress, and the solid-state image sensor 1 The thermal effect on itself and the mounted parts is extremely small, and the reliability of the device can be maintained.

However, as mentioned above, since there are first and second weld interfaces, the contact resistance value during seam welding becomes unstable, and as a result, it is difficult to maintain a continuous and uniform welding condition over the entire seal area. In some cases, temporary sudden heat generation may cause damage to the glass plate 1 of the lid during seam welding.
All abnormalities such as cracks are listed in 5.

In order to eliminate the above drawbacks, it is necessary to minimize fluctuations in contact resistance during seam welding and perform welding under stable welding conditions. This problem can be almost solved by reducing the number of weld interfaces during seam welding from the conventional two interfaces to one interface.

Furthermore, as a lid structure conventionally used for sealing the pan cage of a semiconductor device, a structure in which a low-melting metal brazing material 18 is pre-deposited on the lid 17 side is used, as shown in FIG. 0 The above-mentioned Ritsukube Y is, for example, 4
2 alloy is used.

In the lid 17 with the brazing material 18 welded in advance in this way,
Since the brazing material has already been melted and bonded onto the lid, it becomes one welding interface on the package body side during sealing, and there is no drawback as described above.

However, if this lid structure is applied to a lid that requires light transmission, which is unique to solid-state imaging devices, when welding the low melting point metal brazing material to the lid, the light-receiving characteristics of the solid-state imaging device will be This generates contamination i''L to the extent that it affects the IJ, and also adds thermal stress to the entire IJ node, which is not suitable for a solid-state imaging device.

<Object of the Invention> The present invention has been made in view of the above-mentioned problems of the conventional package sealing method for solid-state imaging devices. To provide a seam welding seam sealing method.

<Example> Part 1 (2) is a concrete example for explaining an example according to the present invention:
＠This is a cross-sectional view of the imaging device, and the same parts as in the conventional device are designated by the same reference numerals. The package 2 on which the solid-state image sensor 1 is mounted and the lid 9 are sealed with the package-side metal frame 8 and the lid-side metal frame 11 facing each other, or the surface of the metal frame 8 on the package side is sealed with a lid. Before facing the side 9, a low melting point metal brazing material 20 is welded in advance. Welding of the brazing filler metal 20 to the package-side metal frame 8 may be performed at any step before soma welding. Moreover, instead of the welded low melting point metal brazing material 20, a paste-like low melting point metal may be printed and applied onto the metal frame 8 and then heated and reflowed.

The metal frame 8 on the package side to which the low melting point metal brazing material 20i has been welded and the metal frame ll on the lid 9 side are placed opposite each other, and the welding electrode 16
energize. The metal frame 11 and the brazing material 20 are welded to generate heat due to contact resistance, and the package 2 side and the lid 9 side are closely attached. By welding around the lid, the solid-state imaging device 1 can be hermetically sealed.

<Effects of the Invention> According to the above invention, in a method of hermetically sealing a package equipped with a solid-state image sensor with a transparent thin plate by seam welding, a low melting point metal brazing material for welding is formed in advance on the package side. Therefore, the interface during welding is only on the lid side, and it is possible to achieve stable airtight sealing with stable heat generation.
You can get highly reliable equipment. Furthermore, since the brazing material is preliminarily welded to the package side before soma welding, it does not contaminate the transparent thin plate and does not interfere with the operation of the solid-state imaging device.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view for explaining an embodiment of the present invention, FIG. 2 is a cross-sectional view showing an example of a conventional solid-state imaging device, and FIGS. 3 and 4 are cross-sectional views showing an example of a conventional LIT. Figure, 5th
The figure is a cross-sectional view showing an example of a lid conventionally used for sealing semiconductor devices. 0 1: Solid-state image sensor 2: Package 8: Metal agent
Patent attorney Aihiko Fukushi (and 2 others) Figure 1

Claims (1)

[Claims] l) A method in which the solid-state image sensor is placed on the bottom of the recess and the package body and the translucent thin plate covering the opening of the package body are sealed by soma welding via a brazing material. It is characterized in that it is formed in advance on the metal frame for seam welding on the side of the joint body side, and the metal material for pool welding formed as a translucent thin plate is opposed and welded to the filler metal on the side of the joint body side. A method for sealing a solid-state image sensor.