JPH06132439A - Plating method for ceramic package - Google Patents

Abstract

PURPOSE:To obtain a product having a uniform plated thickness even in a pin grid array-type ceramic package provided with a chip-mounting cavity in the same direction as a lead terminal. CONSTITUTION:A bonding pad 3 which is exposed in a chip-mounting cavity 2 in a pin grid array-type ceramic package 11 provided with the cavity 2 in the same direction as a lead terminal 4 and the lead terminal 4 are electrolytically plated by using a conductive sheet material 12 as a common electrode in a state that the lead terminal 4 has been pressed to the tip. At this time, a window 13 whose size corresponds to the size of the cavity 2 is formed in the conductive sheet material 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of plating a pin grid array type ceramic package having a chip mounting cavity in the same direction as the lead terminals.

[0002]

2. Description of the Related Art Conventionally, a pin grid array type ceramic package has a structure as shown in FIG.
The ceramic substrate 21, a cavity 23 formed in the central portion of the ceramic substrate 21 for accommodating a chip 22 such as an IC or LSI, a large number of bonding pads 24 formed on the upper surface of the ceramic substrate 21, and the ceramic substrate 21. The bonding pad 24 is formed on the lower surface and the lead terminals 25 are electrically connected to each other.

In the pin grid array type ceramic package having the above-mentioned structure, in order to improve conductivity and prevent oxidative corrosion, the exposed portion of the bonding pad 24 in the cavity 23 and the lead terminal 25 are made of nickel, gold or the like. It is necessary to plate, and as shown in FIG. 3, a lead wire 26 for plating that extends the bonding pad 24 to the end surface of the package is provided, the side surface of the package is brought into contact with the common electrode 27, and power is supplied from the common electrode 27 for electrolytic plating. Processing was being carried out.

In the above-described conventional plating method, the lead wire 26 for plating, which is unnecessary after the plating process, remains inside the package, and thus there are various problems such as the failure of speeding up the signal transmission of the package. . In order to solve this problem, the present applicant has proposed in Japanese Patent Application No. 4-64763 that a conductive plate material is pushed onto the tip of the lead terminal of the package so that electrolytic plating can be performed without using the lead wire 26 for plating. By applying this conductive plate material as a common electrode, electrolytic plating is provided.

[0005]

However, even in the plating method disclosed in Japanese Patent Application No. 4-64763 mentioned above, the chip mounting method is carried out in the same direction as the lead terminal 25 as shown in FIG. If this method is applied to a specially shaped pin grid array type ceramic package having a cavity 23, the gap between the package and the conductive plate material 28 is small, and the conductive plate material 28 acts as a mask during electrolytic plating. 23 and the metallization layer on the bonding pad 24 and the lead terminal 2
There was a problem that the plating did not adhere uniformly on the No. 5 coating.

The object of the present invention is to solve the above problems,
It is an object of the present invention to provide a method for plating a ceramic package in which a pin grid array type ceramic package having a chip mounting cavity in the same direction as the lead terminals can obtain a product having a uniform plating thickness.

[0007]

According to the method of plating a ceramic package of the present invention, a bonding pad and a lead terminal exposed in the cavity of a pin grid array type ceramic package having a cavity for mounting a chip in the same direction as the lead terminal. In electroplating the conductive plate material as a common electrode in a state where the conductive plate material is pressed against the tip of the lead terminal, the conductive plate material is provided with a window portion having a size corresponding to the size of the cavity. It is a feature.

[0008]

In the above structure, the window portion is provided at the portion corresponding to the cavity of the conductive plate material, so that the electrolytic plating solution easily flows between the conductive plate material and the package, especially the cavity. Further, since the electrode forming the electroplating tank for performing the electroplating process and the bonding pad of the cavity to which the plating is attached face each other, the current distribution between the electrode and the bonding pad can be made uniform. As a result, even in the case of a pin grid array ceramic package having a chip mounting cavity in the same direction as the lead terminals, a product plated with a uniform thickness can be obtained.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a state in which a method for plating a ceramic package according to the present invention is carried out, and FIG.
Shows a side view and FIG. 1 (b) shows a front view. In the example shown in FIGS. 1A and 1B, the ceramic package 11 has a ceramic substrate 1 similar to the conventional example.
A cavity 2 for mounting an IC chip (not shown) provided in the central portion of the ceramic substrate 1, a bonding pad 3 partially exposed in the cavity 2, and a bonding pad 3 electrically connected to each other. , And the lead terminal 4 formed on the same surface as the cavity 2 of the ceramic substrate 1.

Then, the conductive plate material 12 is pressed against the tip of the lead terminal 4 of the ceramic package 11, and the bonding pad 3 and the lead terminal 4 are fed with the conductive plate material 12 as a common electrode. A feature of the present invention is that a window portion 13 having a size corresponding to the size of the cavity 2 is provided at a position corresponding to the cavity 2 in the central portion of the conductive plate material 12. Since the size of the window 3 is the same as the size of the cavity 2, the contact between the lead terminal 4 and the conductive plate 12 is not hindered. As the conductive plate member 12, it is preferable to use, for example, a conductive rubber having a resistance of 1 Ω / □ or less.

FIG. 2 is a view showing a state where the ceramic package provided with the conductive plate material 12 having the structure shown in FIG. 1 is actually mounted on the jig 15 for electrolytic plating. As shown in FIG. 2, four rows of ceramic packages 11 are horizontally mounted together with the conductive plate material 12 on both sides of a durable hook-shaped jig 15. Power transmitting plate material 12
Are arranged so as to be outside the ceramic package 12, and are configured to be electrically fed through the attached jig 15.

In the state shown in FIG. 2, the hook-shaped portion of the jig 15 is electrically connected to one of the electrodes of the electroplating apparatus and is hung, and the electroplating tank also functions as the other electrode of the electroplating apparatus. By immersing in the electrolytic plating solution and supplying electric power to the electroplating tank and the conductive plate material 12 in this state, it is possible to perform electrolytic plating on the bonding pad 3 and the lead terminal 4 exposed in the cavity 12.

The present invention is not limited to the above-mentioned embodiments, but various modifications and changes can be made. For example, in the above-described embodiment, the shape of the window portion 13 is the same quadrangle as the shape of the corresponding cavity 2, but this shape is not limited to this, and other shapes such as a circle and an ellipse. It is obvious that the effect of the present invention can be achieved as in the case of a quadrangle if the window has an opening of a size corresponding to the size of the cavity. Further, although FIG. 2 shows the actual state of electrolytic plating, it is also clear that the electrolytic plating method is not limited to the exemplified method.

[0014]

As is apparent from the above description, according to the present invention, since the window portion is provided at the portion corresponding to the cavity of the conductive plate material, the electrolytic plating solution is provided between the conductive plate material and the package, especially the cavity. Becomes easy to flow in,
Since the electrode forming the electroplating tank for the electroplating process and the bonding pad of the cavity to which the plating is attached face each other, the current distribution between the electrode and the bonding pad can be made uniform, and the lead terminal and Even with a pin grid array ceramic package having chip mounting cavities in the same direction, a product plated with a uniform thickness can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a state when a method for plating a ceramic package of the present invention is carried out.

FIG. 2 is a diagram showing a ceramic package provided with a conductive plate material having the structure shown in FIG. 1 actually mounted on a jig for electrolytic plating.

FIG. 3 is a diagram showing a configuration of an example of a conventional pin grid array type ceramic package.

FIG. 4 is a diagram showing a state when a conventional ceramic package plating method is carried out.

[Explanation of symbols]

 1 Ceramic Substrate 2 Cavity 3 Bonding Pad 4 Lead Terminal 11 Ceramic Package 12 Conductive Plate 13 Window

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H01L 23/12

Claims (1)

[Claims] 1. A state in which a bonding pad and a lead terminal exposed in the cavity of a pin grid array type ceramic package having a cavity for mounting a chip in the same direction as that of the lead terminal are pressed against a tip of the lead terminal with a conductive plate material. In the electroplating using the conductive plate material as a common electrode, the conductive plate material is provided with a window portion having a size corresponding to the size of the cavity.