JP3290259B2 - Gold-plated electronic component and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electronic component and a manufacturing method thereof, which is gold-plated.

[0002]

2. Description of the Related Art In the manufacture of electronic components used in semiconductor devices, gold plating is applied to required parts for the purpose of improving the reliability of products, but a semiconductor chip is mounted and aluminum wires are used. In the case of an electronic component such as a stem to be bonded, there is a problem of the bondability between the aluminum wire and the gold plating of the bonding portion. That is, in order to reliably join the aluminum wire and the gold plating, it is preferable that gold grows well in the gold plating layer. Therefore, a small amount of a crystal modifier is conventionally added to the gold plating bath. Plating.

As a crystal modifier added to a gold plating bath,
Conventionally, Tl (thallium), As (arsenic) or Pb
(Lead) is used. These crystal modifiers promote the growth of gold crystals in the gold plating layer and apply gold plating with good wire bonding properties. When gold plating is actually applied to the base material of the electronic component, for example, nickel plating is applied as a base plating, and gold plating is applied to the base plating.

[0004]

By the way, when gold plating is performed using a gold plating bath to which Tl is added as a crystal modifier, compared to other baths using As or Pb as a crystal modifier. It is characterized in that gold crystals grow clearly and the bondability with the aluminum wire in the initial state (before aging at a high temperature) is improved. At this time, in order to prevent pinholes, the thickness of the gold plating needs to be 1.0 μm or more. However, when the plating thickness increases and the eutectoid content of Tl in the plating layer increases, cracks occur at the interface between the aluminum wire and the gold plating bonded when aged at a high temperature, which has a problem of adversely affecting the bondability. .

The reason why cracks are formed at the interface between the aluminum wire and the gold plating as described above is that an intermetallic compound that easily causes cracks between aluminum and gold is formed at the interface by heat treatment, and Tl promotes this growth. It is considered to act to make it work. On the other hand, when a gold plating bath using As or Pb as a crystal modifier is used, there is a feature that cracks do not occur at the interface between the aluminum wire and gold, but the effect of crystal adjustment is higher than that of the Tl bath. Since it is not stable, there is a problem that it is difficult to bond the aluminum wire and the gold plating in the initial state.

SUMMARY OF THE INVENTION The present invention has been made to solve these problems, and it is an object of the present invention to obtain a favorable bonding property between an aluminum wire and a gold-plated bonding portion, thereby improving reliability. It is an object of the present invention to provide a gold-plated electronic component capable of performing high wire bonding and a method of manufacturing the same.

[0007]

The present invention has the following arrangement to achieve the above object. That is, the electrostatic Gold Plated child part, formed by the gold plating Plating
Layer, a gold plating layer as a base layer which is deposited and formed by gold plating bath with the addition of As or Pb as a crystal modifier
And a gold plating bath with Tl added as a crystal modifier
The outer surface formed on the surface of the gold plating layer serving as the underlayer
And a gold plating layer serving as a layer . Also, when manufacturing the gold plated electronic components, wherein
Gold plating, plated with gold to be a base layer using a gold plating bath with the addition of As or Pb in electronic components as a crystal modifier, the surface of the gold plating of the base layer, the Tl as a crystal modifier It is characterized in that gold plating for forming an outer layer is performed using the added gold plating bath.

[0008]

When a gold plating is applied to a bonding portion for bonding an aluminum wire, As is used as a crystal adjusting agent.
Or <br/> gold plating layer as a base layer is deposited formed by gold plating bath with the addition of Pb, the by Ri outer gold plating bath prepared by adding Tl on the surface of the gold plating layer of the base layer gold plating To form a Tl bath formed by gold plating .
Good bondability in the initial state of the gold-plated layer and the aluminum wires of the outer layer, a gold plating layer of the base layer that is more formed gold plating <br/> of A s or Pb bath and aluminum Wa
Can be obtained both good bonding properties after aging with the ear, it is possible to obtain an aluminum wire and electronic components excellent gold plating bondability.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. According to the method for producing a gold-plated electronic component according to the present invention, when a base of an electronic component is plated with gold, the substrate is plated with a base and then As or P is used as a crystal modifier.
It is characterized in that the base layer is plated with gold using a gold plating bath to which b is added, and then the outer layer is further plated using gold plating bath to which Tl is added as a crystal modifier.

FIG. 1 is an explanatory view showing a case where the above-described gold plating method is applied to a stem used as an electronic component as an embodiment of a gold-plated electronic component. FIG. FIG. 4 shows an explanatory diagram to which the method is applied.
In FIG. 1, reference numeral 10 denotes a substrate (eyelet) of an electronic component, 9 denotes a lead fixed to the substrate 10 by glass, and a nickel plating 12 is provided on the substrate 10 and the lead 9 as a base plating. The underlayer gold plating 14 and the outer layer gold plating 16 are further provided. That is, the gold plating layer has a two-layer structure of the base layer gold plating 14 and the outer layer gold plating 16.

On the other hand, in the conventional method shown in FIG. 2, a nickel plating 12 is provided on a base material 10 as a base plating.
Gold plating 18 is applied thereon. This gold plating is based on a gold plating bath to which Tl is added as a crystal modifier, or a gold plating bath to which As or Pb is added as a crystal modifier, but in any case, there is only one gold plating layer.

[0012] Thus, the gold plating layer as shown in FIG. 1 with respect to the bonding portion of the top portion or the like of the lead 9 gold-plated conductive <br/> child component of this embodiment of bonding the aluminum wire It is characterized in that it is formed in two layers, and among the gold plating layers, the gold plating 14 of the underlayer is A
It is characterized in that a gold plating bath to which s or Pb is added is used, and the gold plating 16 of the outer layer is formed by using a gold plating bath to which Tl is added as a crystal modifier.

The results of a wire tensile test performed on the above-mentioned stem by applying gold plating by the conventional method and the method of the present invention are shown below. The plating baths used in the test are as follows. (Priming plating bath) Watt nickel plating bath (bath temperature 60 ° C, pH 2.5) Nickel sulfate 240 g / L Nickel chloride 45 g / L Boric acid 30 g / L Nickel sulfamate plating bath is used as the base plating bath You can also.

(Gold plating bath) (bath temperature 65 ° C., pH 4.
5) Gold potassium cyanide 25g / L bath temperature 6
5 ° C ・ citric acid 90g / L ・ potassium citrate 90g / L pH
4.5 The amount of Tl added in the Tl bath was 10 ppm,
The addition amounts of As and Pb in the bath b were both 3 ppm.
The plating conditions are a current density of 0.1 A / dm ² .

[0015] The tensile strength test of the wire was measured after bonding using an aluminum wire, in an initial state before aging, and after maintaining at 200 ° C for 60 hours. The test results of the tensile test are shown in the table below.

[0016]

[Table 1]

In the table, the term "Tl / As bath" refers to an As bath used as a base layer gold plating and a Tl / As bath used as an outer layer gold plating.
The results of the samples using the bath, the Tl bath, the As bath, and the Pb bath show the results of the samples plated with gold only in each of the gold plating baths. The total thickness of the gold plating layer was 1.
Although it was 5 μm, in the Tl / As bath, 1.
Gold plating of 0 μm thickness and 0.5 μm thickness was performed in a Tl bath.

As shown in Table 1, when the Tl bath is used alone, the tensile strength in the initial state is high,
The bondability after aging deteriorated, and when using the As bath or the Pb bath alone, the bondability in the initial state was low although the bondability was relatively maintained after aging. On the other hand, when using the Tl / As bath, the bonding strength in the initial state is high, and the As
A good result was obtained in that the same bondability as that obtained by a single bath such as a bath could be maintained.

FIGS. 3 to 6 show the results of inspection of the surface condition of the gold plating of each of the above samples by X-ray diffraction.
FIG. 3 shows the results for the samples in the Tl / As bath, FIG. 4 shows the results for the Tl bath, FIG. 5 shows the results for the As bath, and FIG. 6 shows the results for the samples in the Pb bath. From these inspection results, it was found that when using the Tl / As bath, the gold plating reflects the properties of both the Tl bath and the As bath. It should be noted that instead of applying gold plating using an As bath as a base layer for gold plating using a Tl bath, Pb was used instead.
The same result as in the above example can be obtained when gold plating is performed in a bath.

In the above embodiment, the results of a test performed on the stem as shown in FIG. 1 have been described. However, when gold plating excellent in bonding property with an aluminum wire is applied, first, an As bath is used as in the embodiment. Alternatively, a method of applying a base metal plating by a Pb bath and further applying a gold plating by a Tl bath is not limited to a stem, but may be applied to various electronic components that require bonding by aluminum wires, such as a lead frame for a semiconductor device. It is possible to apply to. Further, the present invention can be used for a product in which the entire base material is plated with gold, and a product in which gold plating is partially applied.

[0021]

According to the present invention, a gold-plated electronic component according to the present invention is provided.
, As described above, can be provided as an electronic component which has been subjected to bonding with excellent gold plating of aluminum wire, it is possible to provide a highly reliable product. According to the manufacturing method of the present invention ,
Plating bath with As or Pb added as crystal modifier
Apply gold plating for the underlayer using
On the surface of the metal plating, Tl was added as a crystal modifier.
By applying gold plating that will be the outer layer using a bath,
Prevents generation of cracks at the interface between the A Rumi bromide wire and gold exhibits remarkable effects such as can be suppressed that the bonding strength of the aluminum wire is reduced by aging.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example in which the method of the present invention is applied to a stem component.

FIG. 2 is an explanatory view showing an example in which a conventional method is applied to a stem component.

FIG. 3 shows X of a gold plating layer formed by a Tl / As bath.
It is a graph of a line diffraction.

FIG. 4 is a graph of X-ray diffraction of a gold plating layer formed by a Tl bath.

FIG. 5 is a graph of X-ray diffraction of a gold plating layer formed by an As bath.

FIG. 6 is a graph of X-ray diffraction of a gold plating layer formed by a Pb bath.

[Explanation of symbols]

 Reference Signs List 10 base material 12 nickel plating 14 gold plating of underlayer 16 gold plating of outer layer 18 gold plating

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C25D 3/48 C25D 5/10 C25D 7/00 H01R 9/16

Claims (2)

(57) [Claims] 1. A gold plating is decorated with electronic components, the gold plating layer formed by plating, deposited and formed by gold plating bath with the addition of As or Pb as a crystal modifier
Gold plating layer serving as an underlayer, and T
gold plating to be the underlying layer by gold plating bath with the addition of l
Gold plating layer, which is the outer layer deposited on the surface of
Gold plated electronic component, characterized in that Ranaru. 2. A gold plating to produce a decorated with electronic components
When the gold plating, applying <br/> gold plating underlying layer using gold plating bath with the addition of As or Pb in electronic components as a crystal modifier, the surface of the gold plating of the base layer a method of manufacturing an electronic component which is gold-plated, characterized in that applying gold plating to be the outer layer using a gold plating bath prepared by adding Tl as a crystal modifier.