JPH0736952B2 - Surface coating structure of metallized metal layer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a surface coating structure of a metallized metal layer, and more particularly to an electronic component such as a semiconductor element housing package for housing a semiconductor integrated circuit element or a multilayer wiring board. The present invention relates to the surface coating structure of the metallized metal layer in.

[Conventional technology]

Conventionally, a leadless package (chip carrier) for accommodating an electronic component, for example, a semiconductor integrated circuit device is a second type.
As shown in the figure, it is made of an electrically insulating material such as ceramic or glass, and is used for brazing the lid on its upper surface and for connecting the semiconductor integrated circuit element to the external electric circuit on the outer peripheral portion, that is, the side surface and the bottom surface. Metallized metal layer made of refractory metal powder such as tungsten (W) and molybdenum (Mo)
It is composed of an insulating base 11 on which 12a and 12b are formed and a lid 13, and a semiconductor integrated circuit element 14 is housed inside an insulating container made of the insulating base 11 and the lid 13 and the lid 13 is formed on the insulating base 11. A semiconductor device is obtained by brazing and hermetically sealing the inside of the insulating container.

This conventional chip carrier has an insulating substrate 11 for connecting a semiconductor integrated circuit element 14 housed inside to an external electric circuit.
The metallized metal layer 12b on the bottom surface is brazed and attached to the wiring conductor 16 of the external electric wiring substrate 15 via the brazing material 17, and the metallized metal layer 12b on the bottom surface of the insulating substrate 11 has a strong brazing strength on its surface. Nickel (Ni) and gold (A
The metal layer consisting of u) is coated by plating.

At the same time, the lid 13 is firmly brazed to the metallized metal layer 12a on the upper surface of the insulating substrate 11, and nickel (Ni) and gold (Au), which have good wettability of the brazing material in order to complete the hermetic sealing of the insulating container. ) Is coated by plating.

However, since the insulating base 11 cannot be directly plated and the circulation of the plating solution is poor, it is not possible to cover the surface of the insulating base 11 on the side surfaces of the metallized metal layers 12a and 12b with the nickel plating layer. A slight gap is formed between the nickel plating layer and the insulating substrate 11. Therefore, if moisture contained in the atmosphere adheres to a portion of this gap, the nickel plating layer will have a gap corrosion action due to the difference in oxygen concentration, and the nickel plating layer will have an oxide (rust).
May form hydroxide or hydroxide and cause discoloration.

Furthermore, since the oxides (rust) and hydroxides have the property of being electrically conductive and easily diffused, for example, in a chip carrier in which many metallized metal layers 12b are formed in close proximity, the oxide ( Due to diffusion of rust) or hydroxide, a short circuit occurs between the adjacent metallized metal layers 12b, which causes a serious defect that the function as an electronic component is impaired.

Therefore, in order to eliminate such a drawback, in place of the nickel metal layer coated on the surface of the metallized metal layer, chemically stable and conductive rust is not generated, and it is extremely reactive with the brazing material ( Platinum (Pd) with good wettability
Alternatively, the present applicant has previously proposed coating a metal layer containing these alloys as a main component by plating.

[Problems to be solved by the invention]

However, when the metal layer containing platinum, palladium, or an alloy thereof as a main component is directly formed on the metallized metal layer made of a refractory metal powder such as tungsten or molybdenum, the crevice corrosion effect in the plated metal layer is effective. However, the metal containing platinum, palladium, or an alloy thereof as a main component cannot be coated to a uniform thickness on the metallized metal layer because of its poor throwing power. When more mechanical stress is applied, a part of the plated metal layer peels off from the metallized metal layer, which causes the burn-in test to check the characteristics of the semiconductor integrated circuit element (when a high temperature heat history is applied to the semiconductor integrated circuit element, It is promoted when a test to check the change in characteristics is performed, and the lid of the plated metal layer is brazed. The part or the part brazed to the wiring conductor of the external electric circuit is completely peeled off from the metallized metal layer, and as a result, the attachment connection of the semiconductor device to the external electric circuit is incomplete, or the insulation is isolated. There was a problem that the hermetic seal of the container was broken.

[Object of the Invention]

The present invention has been devised in view of the above-mentioned drawbacks, and an object thereof is to prevent the airtight sealing of an insulating container from being broken even if a burn-in test or the like for checking a semiconductor integrated circuit element is performed, and an electronic device such as a semiconductor device. It is an object of the present invention to provide a surface coating structure of a metallized metal layer capable of reliably connecting a component to an external electric circuit.

[Means for solving problems]

The present invention provides a metal having at least two layers, a first metal layer containing cobalt (Co) as a main component and a second metal layer containing platinum (Pt) as a main component, on the surface of a metallized metal layer on an insulating substrate. It is characterized in that the layers are layered and coated.

In the present invention, when the first metal layer containing cobalt as the main component is provided on the surface of the metallized metal layer and the second metal layer containing platinum as the main component is layer-coated on the first metal layer, the cobalt is the metallized metal layer. And a metal layer containing platinum as a main component, which can be layered and coated with high adhesion and is less susceptible to the above-mentioned crevice corrosion action than nickel, and is a chemically stable metal. Layers can be obtained.

〔Example〕

Next, the present invention will be described in detail based on the embodiment shown in FIG.

FIG. 1 is an enlarged cross-sectional view of an essential part showing a chip carrier (leadless package for housing a semiconductor integrated circuit device) as an example for explaining a surface coating structure of a metallized metal layer of the present invention. In the figure, 1 is an insulating base made of an electrically insulating material such as ceramic or glass, and 5 is a lid. The insulating base 1 and the lid 5 constitute an insulating container for housing the semiconductor integrated circuit element 6. The insulating base 1 has a stepped recess in the center of its upper surface that forms a space for accommodating the semiconductor integrated circuit device 6, and the semiconductor integrated circuit device 6 is attached to the bottom of the recess with an adhesive. Has been done.

A metallized metal layer 2 is formed on the insulating substrate 1 from the bottom surface of the recess and the upper surface of the recessed step to the bottom surface through the side surface. On the upper surface of the recessed step of the metallized metal layer 2, the electrode of the semiconductor integrated circuit element 6 is formed. Are electrically connected via the wire 7.

The metallized metal layer 2 is made of a high melting point metal powder such as tungsten and molybdenum, and is formed on the outer peripheral portion of the insulating substrate 1 by using a conventionally known thick film method such as screen printing.

Further, the metallized metal layer 2 has a first metal layer 3 containing cobalt as a main component and a second metal layer 4 containing platinum as a main component on the bottom surface of the concave portion, the stepped top surface and the side bottom surface.
Are each layered by plating or the like, and the metallized metal layer 2 is covered with two layers of a metal layer containing cobalt as a main component and a metal layer containing platinum as a main component.

A seal ring 8 made of an electrically insulating material such as ceramic or glass is attached to the upper surface of the insulating substrate 1, and a metallized metal layer 2a is formed on the upper surface of the seal ring 8 by the same method as described above. The first metal layer 3a containing cobalt as a main component and the second metal layer 4a containing platinum as a main component are layered and coated on the upper surface of the first metal layer 3a.

Kovar (Fe-Ni-Co alloy) is formed on the second metal layer 4a.
The lid 5 that is plated with gold (Au) is gold (Au) -tin (S
n) It is attached via an alloy brazing material, whereby the void inside the chip carrier is completely airtightly sealed from the outside air, and the final product is a semiconductor device.

Thus, according to the present invention, a metal layer containing cobalt as a main component, which has a large adhesion to the surface of the metallized metal layer formed on the outer peripheral part of the insulating container and the upper surface of the seal ring, and a chemically stable platinum main component. As a result of providing at least two metal layers, the metal corrosion metal layer and the plated metal layer have a high adhesion strength, and the plated metal layer does not separate from the metallized metal layer. At the same time, the brazing of the insulating base and the lid and the brazing of the semiconductor device and the external electric wiring board can be made extremely strong.

The present invention is not limited to the above-mentioned embodiment,
For example, the present invention can be applied to electronic components having a metallized metal layer such as a leaded semiconductor element housing package and a multilayer wiring board.

Next, the operation and effect of the present invention will be described based on the following experimental examples.

[Experimental example]

(I) Evaluation sample A green ceramic body made of alumina was molded according to the shape of the chip carrier shown in FIG. 1, and 40 patterns with a length of 1.5 mm, a width of 0.5 mm and a thickness of 20 μm were formed on the bottom surface, and on the top surface. A ring-shaped pattern with a width of 1.2 mm and a thickness of 20 μm is printed and formed using a metallizing paste made of tungsten, molybdenum, manganese, etc., and this is heated in a reducing atmosphere (nitrogen-hydrogen atmosphere) at about 1400-1600 ° C. It is fired at a temperature to form a metallized metal layer on the surface of the ceramic body. Next, as shown in Table 1, each metallized metal layer surface is coated with platinum, cobalt, nickel-gold by plating (above, comparative example) and cobalt-platinum plating (product of the present invention). Was manufactured, and 100 of each were prepared as samples for each evaluation test.

Then, next, the following evaluation tests were performed using the above evaluation samples. The results are shown in Table 1.

(II) Gap corrosion test Twenty-five of the above evaluation samples were sequentially subjected to 450 ° C. assuming the temperature applied when attaching the semiconductor integrated circuit element and the temperature applied when hermetically sealing the insulating container. 2 minutes at temperature, 430
Hold at a temperature of ℃ for 10 minutes, then MIL-STD-883-100
240 hours (10 cycles) of temperature and humidity cycle test specified in 4
In addition, the metallized metal layer and the plating layer applied to the surface of the metallized metal layer were observed with a microscope, and the number of discolored ones was examined to calculate the discoloration occurrence rate.

(III) Solderability test Twenty-five evaluation samples described above were sequentially held at 450 ° C for 2 minutes and 430 ° C for 10 minutes in the same manner as in the (II) crevice corrosion test, and then the MIL-STD-883C 2003.2 The surface of the sample to be evaluated was exposed to water vapor for 8 hours according to the method specified in the solder adhesion, and the eutectic solder in the molten state controlled at 245 ± 5 ° C
It was soaked for a second, and a solder having a wetted area of 95% or more with respect to the metallized metal layer was regarded as a good product, and the percentage thereof was calculated.

(IV) Brazing Strength Test The 25 evaluation samples above were sequentially held at 450 ° C. for 2 minutes and 430 ° C. for 10 minutes in the same manner as in the above (II) crevice corrosion test, and then the metallized metal on the bottom surface of each sample. 0.5m diameter in layers
Attach the mφ copper wire with solder. Next, assuming this for a burn-in test to check the characteristics of the semiconductor integrated circuit, hold it at a temperature of 175 ° C for 168 hours, then pull the copper wire in the direction perpendicular to the metallized metal layer and examine the brazing strength. The average price was calculated.

(V) Airtight sealing test The 25 evaluation samples above were subjected to the same test as the (II) crevice corrosion test.
After holding at a temperature of 450 ° C for 2 minutes, a Kovar plate plated with gold-tin alloy brazing material was joined to the annular metallized metal layer on the upper surface of the sample to hermetically seal the inner cavity of the insulating substrate. Stop. After that, 30 cycles of -65 ℃ and + 150 ℃ temperature cycles, 10 cycles of 3000G impact test and 165 hours of temperature at 175 ℃ assuming burn-in test are performed, and then helium (He) gas is used. The leak inspecting device was used to check the airtightness of the inner space of the insulating substrate and calculate the non-defective rate.

As can be seen from Table 1, Sample No. 15 in which the surface of the conventional metallized metal layer is coated with a nickel-gold metal layer by plating has a high discoloration occurrence rate of 84% due to the thermal diffusion and crevice corrosion of nickel, The rate of non-defective products for soldering is extremely low at 24%, and the rate of non-defective products for hermetic sealing is also low at 92%. In addition, Sample No. 14 with only the cobalt metal layer formed has a 100% discoloration rate due to the significant oxidation of the cobalt metal layer surface, and the brazing strength is as low as 2.1 kg / mm ² , solderability, and airtightness. The failure rate is extremely high in both cases.

On the other hand, in sample No. 1 in which the platinum metal layer was directly provided on the metallized metal layer surface, the brazing strength was extremely low at 1.9 Kg / mm ² due to the inferior platinum uniform electrodeposition and The non-defective rate is as low as 76%.

On the other hand, according to the present invention, there is no occurrence of discoloration, the brazing strength is as high as 3.7 kg / mm ² or more, the good soldering rate is 96% or more, and the good rate of hermetic sealing is Was also extremely high at 100% and was found to have good characteristics.

〔The invention's effect〕

As described above, the surface coating structure of the metallized metal layer of the present invention is excellent in heat resistance and moisture resistance, and has no crevice corrosion action which impairs the function as an electronic component, and does not cause discoloration or deterioration of hermetic sealing. It is also possible to obtain a highly reliable electronic component having excellent reactivity with the brazing material.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of an essential part showing a chip carrier as an example for explaining a surface coating structure of a metallized metal layer according to the present invention, and FIG. 2 is a cross-sectional view of a conventional chip carrier. 1,11 …… Insulating substrate 2,2a, 12 …… Metalized metal layer 3,3a …… First metal layer 4,4a… Second metal layer 5,13 …… Lid

Claims (1)

[Claims] 1. A first metal layer containing cobalt (Co) as a main component and platinum (Pt) on the surface of a metallized metal layer on an insulating substrate.
A surface coating structure for a metallized metal layer, characterized in that a metal layer comprising at least two layers including a second metal layer containing as a main component is layered and coated.