JPH04174544A - Hermetic seal lid - Google Patents

Abstract

PURPOSE:To remarkably improve temperature cycle hermetic seal life, by fusion- welding solder material to at least a part of side surface of a lid main body on which a metal thin film is formed, along said side surface. CONSTITUTION:A metal thin film 12 is formed on one surface of a base board 11 by plating nickel, and a lid main body 13 is constituted. On the whole part of the side surface of the base board 11, solder material 14 is fusion-welded so as to surround the side surface part. The solder material 14 is fusion-welded to the side surface of the main body 13 so as to have a nearly semicircular sectional shape, and stretches as far as the peripheral part of the film 12. A window frame type solder material 14 is engaged with the recessed part of a jig 15. The lid main body 13 is so arranged in the window part of the solder material 14 that the film 12 faces upward, and the main body 13 and the jig 15 are fixed. By heating them, the solder material 14 is fusion-welded to the side surface of the main body 13, and a hermetic seal lid can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hermetic seal lid for sealing an opening of an alumina package in which a semiconductor element such as an IC is housed.

[Prior Art] Conventionally, this type of hermetic seal lid has been manufactured by soldering one or both sides of a rectangular or circular thin flat metal substrate made of iron-based alloy such as 42 alloy or Kovar. nickel plating is applied to the substrate, gold plating is applied to the surface of the nickel plating layer, or nickel is bonded to one or both surfaces of the substrate by hot cladding, etc. It is known that a lid body is formed by forming a metal thin film on the surface of a substrate.

To seal the opening of a recess in a package containing a semiconductor element using such a hermetic seal lid,
First, as shown in FIGS. 10 and 11, a part or all of a thin window frame-shaped solder material 4 having the same external dimensions as the substrate 3 is temporarily bonded to the surface of the lid body l on which the metal thin film 2 is formed. . Next, as shown in FIG. 12, the lid body l to which the solder material 4 has been temporarily bonded is stacked on the metal cooling part 7 formed around the opening of the recess 6 of the package 5 made of alumina, etc. Temporarily fix it with etc.

Alternatively, without temporarily joining the lid body l and the solder material 4, as shown in FIG. Through 4,
It may be overlapped with the metal sealing part 7 formed around the opening of the package 5 and then temporarily fixed.

After that, the lid body 11 temporarily fixed in this way, the solder material 4
, and by heating the package 5 in an oven or the like to fuse the solder material 4 to the sealing part, the lid body l is joined to the metal sealing part 7 and the opening of the package 5 is sealed. It has become.

[Problems to be Solved by the Invention] When joining the hermetic seal lid in this manner, a solder material is interposed in advance between the lid body and the metal sealing portion of the package.

By the way, it is known that an oxide film is formed on the surface of such solder material no matter how strictly it is handled. For this reason, there is a problem that this oxide film adheres tightly to the lid body and the metal sealing part of the package due to the pressure of the clip, impeding the bonding between the two.
two.

On the other hand, the unoxidized 7X solder material inside the oxide film leaks into the recesses of the package and outside the sealing part, which is not in the melted sealing part, and no clean solder material remains in the sealing part. This results in a state where only an oxide film exists on the surface. In particular, if the solder material leaks into the recess of the package, it may be loaded into the recess and adversely affect the functionality of the semiconductor element.

Furthermore, the oxides remaining between the lid body and the package cause poor wetting of the solder material and the generation of voids, resulting in a significant shortening of the life of the temperature cycle hermetic seal.

[Means for Solving the Problems] The present invention has been made to solve the above problems, and
It consists of a lid body with a thin metal film formed on a flat substrate.
In a hermetic seal lid that is bonded via a solder material to an opening of a recess of a package in which a semiconductor element is housed to seal the opening, at least one side surface of the lid main body on which the metal thin film is formed; The soldering material is welded to the side surface along the side surface.

[Operation: In such a hermetic seal lid, an oxide film is formed on the surface of the cover material, which is welded to the side surface of the lid body before joining. Unoxidized solder material oozes into the seal and joins the lid body and package.

On the other hand, the oxide film does not enter the sealing portion and remains outside the sealing portion.

As described above, according to the present invention, since only unoxidized solder material is present in the sealing portion during bonding, it is possible to perform good fusion bonding while suppressing the occurrence of voids and poor wetting.

[Embodiment] FIG. 1 is a perspective view showing an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of this embodiment.

In this embodiment, a metal thin film 12 is formed by nickel plating on one surface of a rectangular flat metal substrate 11 made of 42 alloy, which is an iron-based alloy, to constitute a lid body 13. A solder material 14 is welded to the entire surface of the side surface 11 so as to go around the side surface.

As shown in FIG. 2, this solder material 14 has a substantially semicircular cross-sectional shape and is welded to the side surface of the lid body 13, and its end side extends to the circumferential tightening portion of the metal thin @+2. I'm being forced to do it. Note that an oxide film is formed on the surface of this solder material 14, or the solder material inside this oxide film is not oxidized.

A hermetic seal lid having such a configuration is manufactured, for example, by the following method.

First, a metal thin film 12 is formed by nickel plating one side of a 42 alloy plate material that will become the base 11, and this plate material is punched out from the other side to form a lid body 1 as shown in FIG.
Mold 3. During this punching, by punching out the plate material from the non-nickel plated surface, the nickel plating layer sag and the metal thin film 12 is also formed on the side surface of the lid body I3.

Next, a solder material 14 is welded to this lid body 13, using a jig 15 as shown in FIGS. 4 and 5. This jig 15 is a flat jig body 16 made of alumina.
A rectangular recess 17 having a larger width and length than the lid body 13 is formed on the upper surface of the lid body 13. Further, the solder material 14 is formed into a window frame shape, and the window portion is slightly larger in both width and length than the lid body 13, and the outer edge portion is slightly between the recess 17 of the jig 15 and the groove. It is small and can be fitted into the recess 17.

Therefore, as shown in FIG. 6, a window frame-shaped solder material 14 is fitted into the recess 17 of the jig 15, and the lid body 13 is attached to the window portion of the window frame-shaped solder material 14 using a metal thin film 12. is placed facing upward, and the lid body 13 and jig 17 are fixed with clips 18 as shown in FIG. By heating these in a belt furnace or the like, the solder material 14 is welded to the side surface of the lid main body 13, and a hermetic seal lid as shown in FIGS. 1 and 2 can be obtained.

The hermetic seal lid with this structure has the 8th
As shown in the figure, one surface on which the metal thin film 12 is formed faces downward, and the opening is opened so as to cover the opening of the recess 21 of a package 20 made of alumina or the like loaded with a semiconductor element 19 such as a Si chip. It is closely attached to the circumferential line. However, in this embodiment, since the solder material 14 is welded to the side surface of the lid body 13 in advance, there is no need to insert the window frame-shaped solder material 4 as shown in FIGS. 10 to 13 again. do not have.

Further, a window frame-shaped metal cooling portion 22 is formed at the periphery of the opening of the recess 21 of the package 20 in accordance with the external dimensions of the lid body 13.

Note that the reference numeral 23 in FIG. 8 is an external lead projecting from the side of the package 20.

In this way, the lid main body 13, which is in close contact with the metal cooling part 22 at the periphery of the opening of the recess 21, is temporarily fixed to the package 20 with a clip or the like and heated in an oven or the like.

As a result, the solder material 14 welded to the side surface of the lid body 13 melts, and the unoxidized solder material 14 covered with the oxide film is transferred from the side surface of the lid body 13 to one side of the lid body 13. It oozes into the sealing area between the metal thin film 12 on the surface and the metal sealing part 22 of the package 20, and fuses the lid body 13 to the package 20. At this time, the oxide film formed on the surface of the solder material 14 cannot enter into this sealing part, but remains outside of this sealing part.

As explained above, according to the hermetic seal lid having such a configuration, the oxide film of the solder material 14 is formed on the lid main body 13.
No oxidized solder material 14 is present in the seal between the package 20 and the metal ring 22 of the package 20, and only unoxidized solder material 14 seeps into the seal. Therefore, the bondability between the lid body 13 and the package 20 is not inhibited by the oxide, and poor solder wetting and void generation can be suppressed, extending the life of the temperature cycle hermetic seal. It becomes possible to achieve this goal.

Further, since the solder material 14 oozes out from the outer edge of the metal sealing part 22, the recess 21 in which the semiconductor element 19 is loaded is
Therefore, a situation that would affect the function of the semiconductor element 19 can be prevented.

Furthermore, even if an oxide film is formed on the surface of the solder material 14, bonding can be performed without any problem, so there is no need to handle the solder material 14 with great care, which simplifies complicated management work. becomes possible.

Furthermore, in this embodiment, the solder material 14 is applied to the lid body 1 in advance.
3, there is no need to separately provide solder material 4 at the time of joining as in the example shown in FIG. 13, which also has the advantage of simplifying the work.

In addition, in this embodiment, the solder material 14 after welding and solidification
In order to keep the thickness constant, cylindrical spacers or the like may be used after bonding to the four corners of the surface of the metal thin film 12 of the lid body 13.

Next, FIG. 9 is a plan view showing another example of the jig used for manufacturing the hermetic seal lid of the present invention, and the same parts as the jig 15 described above are given the same reference numerals and will be explained. Simplify.

This jig 24 has a rectangular recess 26 larger in width and length than the lid body 13 on the upper surface of a flat jig body 25 made of alumina. At the pair of opposing corners of the recess 26, fixing claws 27 having a W-shaped cross section are engaged with the pair of opposing corners of the lid body 13 to fix the position of the lid body 13. .27 is formed. On the other hand, a pair of opposing corners other than the pair of corners of the recess 25 have recesses 28 that communicate with these corners, respectively.
28 is formed.

To manufacture the hermetic seal lid of the present invention using the jig 24 having such a configuration, the lid body 13 is placed with the surface on which the metal thin film 12 is formed in the recess 26 of the jig body 25 facing downward.
and fix the position using the fixing claws 27 and 27. Then, fix the lid body 13 with a clip or the like, and add a linear or spherical solder material I4 to the recess 28°28.
and heat it with a belt furnace, etc. As a result, the recess 2
The solder material 14 placed at 8° 2B melts and forms the recess 26.
The liquid flows between the side surface of the lid body 13 and the inner wall of the recess 26 and is welded to the side surface of the lid body 13.

Here, in the hermetic seal lid manufactured by the jig 24 having such a configuration, the fixing claws 27 and 27 of the jig 24 are attached to the pair of opposing corners of the lid body 13 when the solder material 14 is welded. Since these corners are engaged, the solder material 14 is not welded to these corners. That is, the lid body 13
The solder material 14 is welded only to a part of the side surface of the housing and not to the entire part, but when the lid body 13 and the package 20 are joined, the solder material 14 melts and forms a sealing part between the two. Since it is evenly distributed, there is no risk of inhibiting zygosity.

Such a jig 24 has the advantage that it is not necessary to form the solder material 14 into a window frame shape as in the jig 15 and the conventional example, and the work is simple. Further, when fixing the lid body 13 to the jig 24 with a clip or the like and welding the solder material 14, the lid body 13 is attached to the fixing claws 27.
Since its position is determined by 7, the lid body 1
It is possible to prevent a situation where the solder material 14 is unevenly welded to the side surface of the lid body 13 due to deviation of the solder material 14.

In this example, fixing claws 27° 27 and recesses are provided at two pairs of opposite corners of the recess 26 of the jig body 25, respectively.
28.28 is provided, but fixing claws are provided at a pair of opposing corners or all four corners of the recess 26, and the recess in which the solder material 14 is placed communicates with the four sides of the recess 26. It may be arranged so that Further, on the contrary, fixing claws may be provided on the four sides of the recess 26, and the recesses may be provided at the four corners.

[Experiment example Next, an experimental example of the present invention will be given to demonstrate its effects.

In this experimental example, width 150am x length 2 sections x thickness 0.3
After forming a thin metal film by applying nickel plating to a thickness of lOμ on one side of the strip-shaped plate material of 42 alloy (iron-based alloy) of 1-, this plate material was removed from the other side by 10Bm x 10
A large number of lid bodies as shown in FIG. 3 were formed by punching out squares of mm in size. This lid body is punched from the other side, which is not nickel plated, so that the nickel plating layer sag occurs on the side surface.

On the other hand, the solder material is Pb- rolled to a thickness of 100 μm.
10wt%s n, external dimensions 12mm x 12mm,
A window frame shape with a radius of 0.9+* was punched out and thoroughly cleaned.

Next, using an alumina jig as shown in FIGS. 4 and 5, a window frame-shaped solder material was fitted into the recess of this jig. Further, as shown in FIG. 6, the lid body is placed in the window of the solder material with the metal thin film side facing upward, and as shown in FIG. Fixed to a jig.

Then, the lid body and the solder material together with the jig and clip are heated at 300°C or more for 3 minutes at a maximum temperature of 350°C in a belt furnace with a 100% nitrogen atmosphere.
Weld the solder material to the side surface of the lid body and
A hermetic seal lid as shown in the figure was manufactured.

On the other hand, as a comparative example to this experimental example, a hermetic seal lid as shown in FIGS. 1O and 11 was manufactured.

In this comparative example, the width is 1501111 as in the experimental example.
After applying 10 μm nickel plating to one side of a 42 alloy (iron-based alloy) strip plate material of 1× length 2111× thickness 0.3 mm to form a metal thin film, this was 1 On+
A number of square pieces of n+X 10 mm were punched out from the other side to form a large number of lid bodies.

The solder material was Pb-1 rolled to a thickness of 100 μm.
0wt%Sn with external dimensions 10+nmXIO+nm,
A window frame shape with a width of 1 mm was punched out and thoroughly cleaned.

Then, stack a window frame-shaped solder material on top of the lid body with the metal thin film side facing upward, and heat it at 250°C or more for 3 minutes, at a maximum temperature of 290°C.
The lid body and the solder material are welded together in the solid solution coexistence temperature range of the solder by placing it in a belt furnace with a 100% nitrogen atmosphere under the temperature conditions of A hermetic seal lid to which solder material was temporarily bonded was manufactured.

Then, the hermetic seal lids of these experimental examples and comparative examples were stacked with the metal thin film side down on the recess opening of the alumina package, as shown in FIGS. 8 and 12, respectively. It was temporarily fixed using a sealing clip with a strength of 100 g.

In addition, this alumina package has an external dimension of the periphery of the opening of the recess, which is the sealing part, of 10.5 mm x + 0.5 wu.
It is a 90% alumina DIP type with tungsten paste fired on a window frame-shaped part with a width of 1 mm, nickel plating within 10 μm, and gold plating on top of that to a thickness of 2 μm.

The hermetic seal lid and package that have been temporarily fixed in this way are placed in a belt furnace with a maximum temperature of 350°C for 3 minutes at 300°C or higher, and the atmosphere is 90% nitrogen and 10% hydrogen, and solder is added. was melted to seal the package.

The following evaluation tests were conducted on each package to which the hermetic seal lids of the experimental example and the comparative example were joined in this way.

(A) X-ray transmission test The presence or absence of voids at the joint between the hermetic seal lid and the package is inspected.

(B) After peeling off the lid, inspect using an optical microscope. Inspect whether the solder on the inner surface of the lid has spread to areas where no solder is needed and is dripping into the cavity of the alumina package.

(C) After applying a temperature cycle (-65°C to 150°C) for hermetic sealing test, He
Perform a gas trace leak test and a fluorocarbon gloss test to determine hermetic seal life.

The results of these evaluation tests (A) to (C) are shown in the table below.

(Margin below) As is clear from this table, in the hermetic seal lid of the experimental example according to the present invention, no voids were generated at the joint between the lid body and the package, and the solder material did not drip into the cavity. It turns out there isn't.

Furthermore, it can be seen that the temperature cycle hermetic sealing life is improved several times compared to the comparative example.

These results are considered to fully prove the effectiveness of the present invention.

Although Pb-10wt%Sn was used as the solder material in this experimental example, similar results could be obtained using other gold thread solder materials such as Au-20wt%Sn.

[Effects of the Invention] As explained above, according to the present invention, the solder material is welded to the side surface of the lid body, and during joining, the unoxidized solder material inside the solder material is melted. Supplied to the joint.

Therefore, since the oxide film on the surface of the solder material does not directly adhere to the joint, the bondability between the lid body and the package is not inhibited. Furthermore, it is possible to suppress the occurrence of poor wetting and voids, and the life of the temperature cycle hermetic seal can be significantly improved compared to the conventional method.

[Brief explanation of the drawing]

1 and 2 are a perspective view and a cross-sectional view showing an embodiment of the present invention, and FIG. 3 is a sectional view showing the lid body of this embodiment. Furthermore, FIGS. 4 and 5 show a perspective view and a sectional view of the jig used to manufacture this embodiment, and FIG.
8 to 8 show the manufacturing process of this embodiment, and FIG. 9 is a plan view showing another example of the jig. Furthermore, FIG. 1θ and FIG. 11 are a perspective view and a sectional view showing an example of a conventional hermetic seal lid to which a solder material is temporarily bonded, and FIG. 12 is a sectional view showing this example bonded to a package. be. Moreover, FIG. 13 is a sectional view showing the case where the lid body and the solder material are bonded to the package without being temporarily bonded. 1.13... Lid body, 2.12... Metal thin film, 3.11... Substrate, 4.1
4...Solder material, 5.20...Package, 6.21...Recess, 7.22...Metal sealing part, 15.24...Jig, 16.25...Jig Tool body, 17; 26... recess, 2
7... Fixing claw, 28... Recess, 18... Clip, 19... Semiconductor element, 23...
・External lead.

Claims (1)

[Claims] It consists of a lid body with a thin metal film formed on a flat substrate.
In a hermetic seal lid that is bonded via a solder material to an opening of a recess of a package in which a semiconductor element is housed to seal the opening, at least one side surface of the lid main body on which the metal thin film is formed; A hermetic seal lid, wherein the solder material is welded along the side surface of the portion.