JPH07101721B2 - Ag brazed seal ring for integrated circuit and manufacturing method thereof - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a seal ring for encapsulating an integrated circuit chip in a ceramic package, and particularly to mechanically polishing a seal ring material made of a stamped product of a cold rolled material. The present invention also relates to a seal ring with Ag brazing for an integrated circuit, in which Ag brazing is uniformly and surely applied to a predetermined position of the seal ring by performing chemical polishing, and a manufacturing method thereof.

BACKGROUND ART Integrated circuit chips, which are required to have high reliability, are used by being enclosed in an airtight package made of metal or glass in order to facilitate their protection and electrical connection. Today, however, ceramic packages are used. Is the mainstream.

In general, the structure of the ceramic package is such that a multi-layer substrate type in which a plurality of metallized ceramic plates are laminated has a cavity (2) for accommodating an IC chip inside as shown in FIG. Ceramic substrate (1) with metallized frame (3) formed around 2)
The (1 ') and the ceramic cap (4) are joined by Ag brazing in which a metallic seal ring (5) and an Ag brazing frame (6) having the same shape are arranged, and the ceramic substrate (1 2) There are known a structure in which the lead frame (7) is brazed to the end face and a structure in which the lead pin (8) is brazed to the back face of the ceramic substrate (1 ').

In this Ag brazing, an Ag brazing frame (6) which has been punched to have substantially the same size as the seal ring (5) in advance is used, and a seal ring (5), a cap (4), and a ceramic substrate (1).
(1 '), and heat and melt to join them, or when assembling the ceramic package,
Since the arrangement of the Ag brazing frame (6) is complicated, a proposal has been made in which Ag brazing is melted and adhered to the seal ring in advance to facilitate alignment during assembly (for example, JP-A-61-9998,
JP-A-61-248536).

Problems to be solved by the invention The seal ring is a Fe-Ni-based alloy or Fe-Ni-Co-based alloy is processed into a plate shape by cold rolling, and then, a desired shape, such as press working into dimensions. Although a material that has been subjected to punching is used, it has anisotropy of surface roughness in the processing direction during cold rolling, that is, in the rolling direction. Due to the anisotropy, uniform flow to one main surface of the seal ring, which is the surface to be Ag brazing adhered, is prevented, and sufficient sealing may not be obtained in some cases.

Therefore, conventionally, it has been necessary to prepare Ag brazing punched out in approximately the same size as the metal seal ring in advance, or arrange the Ag brazing over the entire circumference of one main surface of the seal ring, which requires a great deal of man-hours. I needed it.

Further, during punching such as press working, the peripheral end face of the obtained seal ring plate, as shown in FIG. 3a, produces a fractured surface along with a sheared surface, resulting in burrs, metal powder, etc. This has been a cause of impeding the sealing and causing acid solution to remain on the fracture surface during gold plating performed after assembly, resulting in swelling of the product after gold plating.

Further, in order to prevent the above-mentioned fractured surface from occurring in the seal ring and increase the ratio of the shear surface in the end face, it is sufficient to use the mold with the clearance of the mold narrowed to the limit during press working. This will significantly shorten the life of the mold.

Furthermore, mechanical polishing such as barrel polishing with alumina or silica is performed in order to remove burrs or the like generated on these fracture surfaces, but in this case, fine powder of alumina or silica adheres to the seal ring surface, and the subsequent steps However, there is a problem that the plating has a bad influence such as swelling.

Further, the sheared surface after pressing has a groove-like roughness in the thickness direction, and there is a problem that Ag brazing flows into the end surface along the roughness.

OBJECT OF THE INVENTION The present invention aims to improve a seal ring for encapsulating an integrated circuit chip in a ceramic package, and in particular, to mechanically and chemically polish a seal ring material made of a stamped product of a cold rolled material. An object of the present invention is to provide a seal ring with Ag brazing for an integrated circuit, in which Ag brazing is uniformly and surely applied to a predetermined position of the seal ring, and a manufacturing method thereof.

SUMMARY OF THE INVENTION The present invention aims to provide a highly reliable seal ring by solving the problems of the prior art, and the properties of the seal ring surface,
As a result of various studies, after cold rolling and stamping the seal ring material, after mechanical polishing such as barrel polishing, chemical polishing using a chemical polishing bath such as phosphoric acid system The working direction during rolling, that is, the anisotropy of the surface roughness generated in the rolling direction on the one main surface that is the surface to which Ag brazing is to be adhered can be reduced, and further, in the fracture surface of the peripheral end surface of the seal ring material. The inventors have completed the present invention by discovering that a smooth and clean surface free of metal powder, mechanical abrasive grains, etc. can be obtained, and Ag brazing can be applied uniformly, reliably, and extremely easily.

That is, the present invention relates to a cap for encapsulating an integrated circuit chip in a ceramic package and a seal ring with Ag brazing interposed between the packages, the seal ring material being a stamped product of cold rolled material, and mechanical polishing. A seal ring with Ag brazing for an integrated circuit, characterized in that Ag brazing is adhered on one main surface consisting of a chemically polished surface having a roughness of 1.5 μm or less in which no abrasive grains remain, In the method for manufacturing a seal ring, a seal ring material made of a stamped cold-rolled material is mechanically polished, and after chemical polishing, the material is housed in a jig having a groove into which the material can be fitted. Then, an Ag brazing material having an arbitrary shape and a required amount is placed at an arbitrary position on one main surface, which is a surface to be deposited with Ag brazing of the material, and is heated to a melting temperature of the brazing material. It is a manufacturing method of the Ag-soldering with sealing ring integrated circuit.

Structure of the Invention In the present invention, the seal ring material is a Fe-Ni-based alloy (for example, 42Ni-Fe alloy) or a Fe-Ni-Co-based alloy (Kovar) in order to match the thermal expansion coefficient with other ceramic parts. ) Is used. In addition, a Cu-based alloy or the like may be used in order to improve heat dissipation from the ceramic package.

Further, in the present invention, the seal ring material is processed into a plate having a thickness of 0.3 mm to 2.0 mm by cold rolling, and then subjected to punching such as press working (hereinafter referred to as press working) to have a predetermined shape, It can be obtained as a molded product of dimensions.

In the present invention, when press working is performed, even if a fracture surface is formed on the peripheral end face of the obtained seal ring material, it can be removed by mechanical polishing performed thereafter, and further by chemical polishing, metal powder and mechanical polishing of the fracture surface can be performed. Since the abrasive grains for use can be removed, it is not necessary to narrow the die clearance to the limit, such as shortening the life of the die.

In the present invention, mechanical polishing is if remove burrs or metal powder caused fracture surface of the seal ring material after press working, well mechanical polishing known nice deviation, alumina (Al ₂ O
₃ ) Barrel polishing using silica (SiO ₂ ) as abrasive grains can be used as appropriate.

The chemical polishing, which is a feature of this invention, uses a seal ring material.
In the case of Fe-Ni alloy and Fe-Ni-Co alloy, sulfuric acid-hydrogen peroxide chemical polishing bath, acid ammonium fluoride-hydrogen peroxide-
A sulfuric acid-based bath is used, and a chemical polishing bath such as an oxalic acid-hydrogen peroxide-based or phosphoric acid-based bath is also used. In the case of Cu-based alloys, a nitric acid-sulfuric acid-hydrochloric acid system bath is used.

By performing the above chemical polishing, the anisotropy of the surface roughness generated in the rolling direction during cold rolling on one main surface of the seal ring material, which is the surface to which Ag brazing is to be adhered, is reduced or eliminated. In order to remove the metal powder and the abrasive particles for mechanical polishing adhering to the fracture surface which is the end surface of the seal ring material, and to apply the Ag brazing evenly and surely only to the intended Ag brazing adhering surface Is required to have a polishing amount of 2 μm or more by chemical polishing so that the difference in surface roughness between the rolling direction of the seal ring material and the direction perpendicular thereto is 0.2 μm or less, and the surface roughness is 1.5 μm or less, More preferably, it is necessary to appropriately select the chemical polishing bath composition, temperature and treatment time so that a smooth and clean surface of 1.0 μm or less is obtained.

The amount of polishing by chemical polishing is preferably 2 μm to 15 μm.

The chemical polishing bath composition, temperature and treatment time vary depending on the composition and surface condition of the seal ring.For example, in the case of an ammonium fluoride ammonium-hydrogen peroxide-sulfuric acid bath, the bath temperature is 20 to 100 ° C. The processing time is 1 to 30 minutes.

In addition, the cleaning after chemical polishing is performed by washing with tap water and pure water several times and then drying with hot air.

Since the seal ring of the present invention, which has been subjected to such chemical polishing, has no roughness anisotropy on the surface and improves the flowability of Ag brazing material in a heated and melted state, it has approximately the same dimensions as the conventional seal ring. It is not necessary to process Ag braze, and as shown in the examples, a seal ring in which the required amount of Ag braze in any shape such as wire, grain, lump, powder, etc. is loaded into the groove of the jig. By only placing a part of one main surface of the one main surface at an arbitrary position and heating and melting, the Ag brazing material uniformly flows over the entire one main surface of the seal ring, and a seal ring having a good sealing property can be obtained. Further, also on the peripheral end surface of the seal ring, the groove-shaped roughness in the thickness direction formed during press working is reduced or reduced, so that the Ag brazing material does not flow into the peripheral end surface of the seal ring.

The Ag solder used in this invention is an Ag-Cu alloy or Ag-Cu-Z.
n alloy or Cd, Ni, Sn, In, Mn, Li, P, Ga, Sb, B
A material containing at least one of i, etc. is used.

The brazing of the Ag brazing material may be performed, for example, in a non-oxidizing atmosphere such as nitrogen gas, usually at a temperature of 780 ° C. or higher, and for a treatment time of 2 to 30 minutes.

The Ag brazing thickness applied to the seal ring is preferably 200 μm or less, more preferably 30 μm to 100 μm.

Example First, as shown in FIG. 1 (a), a seal ring material (10) having a square ring shape of 19 mm × 16 mm × 0.5 mm was obtained from Kovar material by cold rolling and pressing. .

At this time, the roughness of the rolled surface was 1.5 μm or more, and the difference between the surface roughness in the rolling direction of the material and the surface roughness in the direction perpendicular thereto was 0.25 μm.

This seal ring material (10) was barrel-polished with alumina powder to remove burrs with a height of 0.01 to 0.03 mm.

Next, a chemical polishing liquid (liquid temperature 35 ° C.) consisting of 60 vol% hydrogen peroxide, 3 wt% acidic ammonium fluoride, 1 vol% sulfuric acid, and the balance water was used to prepare the seal ring material (10) in the bath.
Chemical polishing was performed by immersion for a minute. After chemical polishing, washing with tap water and washing with running pure water were performed twice.

After washing, the peripheral edge surface of the seal ring (10) which has been subjected to mechanical polishing and chemical polishing, which is the main feature of the present invention, is observed with a 50 × optical microscope. As a result, a schematic diagram based on the micrograph of FIG. 2 is obtained. As shown, the flash height is 0 and the shear surface roughness is
It was 1.0 μm or less, and the difference in surface roughness between the rolling direction of the material and the direction perpendicular thereto was 0.2 μm.

Further, as shown in FIG. 1 (b), the seal ring (10)
Jig (11) having a groove (3) into which the
Then, after inserting the seal ring (10), insert the Ag solder (13) made of 72Ag-28Cu with a size of Φ0.6 × 18.6mm into the seal ring (1
0) placed on one main surface, and in a nitrogen gas atmosphere at 900 ° C,
Braze the seal ring (10) under the condition of 10 minutes, and
A brazed seal ring was obtained.

As shown in Fig. 1 (c), Ag brazing after heating and melting (13a)
Is evenly adhered to one main surface of the seal ring (10), and the thickness of the Ag solder (13a) is within 50 μm ± 10 μm over the entire one main surface of the seal ring (10). It was Moreover, Ag brazing did not flow into the peripheral end surface of the seal ring (10) at all.

EFFECTS OF THE INVENTION When pressing the seal ring material, it is not necessary to narrow the clearance to the limit so as to shorten the life of the mold, and the life of the press mold can be significantly extended.

No metal powder or abrasive particles for mechanical polishing adhere to the sheared surface and fracture surface after press working, which improves the quality of gold plating in the subsequent process.

When brazing to the seal ring, Ag braze has good flowability and can be evenly adhered, and further, it is possible to prevent Ag braze from flowing into the peripheral end surface and the back surface of the seal ring.

When brazing to the seal ring, regardless of the Ag brazing method, work efficiency can be improved.

When brazing to the seal ring, regardless of the shape of the Ag brazing material, the material yield can be significantly improved.

[Brief description of drawings]

1 a, b, c are perspective explanatory views showing a seal ring and a jig and A
It is a sectional view of a g-brazing seal ring. 2 and 3 are schematic diagrams based on micrographs of the peripheral end surface of the seal ring, in which FIG. 2a shows the conventional one and FIG. 3b shows the present invention, and FIG. 2 shows the periphery of the seal ring. FIG. 3 is a schematic front view of the end face, and FIG. 3 is a schematic cross-sectional view of the same. FIG. 4 is a perspective explanatory view of the ceramic package showing the structure of the seal ring plate. 10 …… Seal ring material and seal ring, 11 …… Jig, 12 …… Groove, 13,13a …… Ag wax.

Claims (2)

[Claims] 1. A cap for encapsulating an integrated circuit chip in a ceramic package and a seal ring with Ag brazing interposed between the packages, wherein the seal ring material is a stamped product of cold rolled material, and mechanical polishing is performed. Surface roughness of 1.5 μ
A seal ring with Ag brazing for integrated circuits, characterized in that Ag brazing is adhered on one main surface consisting of a chemically polished surface of m or less. 2. A method for producing a cap for encapsulating an integrated circuit chip in a ceramic package and a seal ring with Ag brazing interposed between the packages, wherein a seal ring material made of a stamped cold-rolled material is used as a machine. After being subjected to polishing, and further subjected to chemical polishing, the material is accommodated in a jig having a groove into which the material can be fitted, and the material is placed at an arbitrary position on one main surface, which is the surface to which Ag brazing is to be applied, A method for manufacturing a seal ring with Ag brazing for an integrated circuit, which comprises placing an Ag brazing filler metal in an arbitrary shape and a required amount and heating it to a melting temperature of the brazing filler metal.