JPS63184347A - Method for unsealing semiconductor package - Google Patents

Abstract

PURPOSE:To conduct accurate analysis without changing the state of the surface of a semiconductor chip by cutting off a sealing resin from a semiconductor package with the exception of the sealing resin sealing the upper and lower surfaces of the semiconductor chip, warming the sealing resin remaining on the upper and lower surfaces of the semiconductor chip with a flame and peeling the sealing resin from the semiconductor chip. CONSTITUTION:The position of a semiconductor chip 2 in a semiconductor package 1 is confirmed through X-ray photographing, etc., a sealing resin 3 in the peripheral section of the semiconductor chip 2 is cut and removed through a mechanical means, and a part in which the semiconductor chip 2 is sandwiched by upper and lower sealing resins 3, 3 is cut out. The sandwich-shaped part is admitted into the flame of a burner, and heated for approximately several sec. Consequently, thermal shock stress works between the semiconductor chip 2 and the sealing resin by the difference of the thermal expansion coefficients of the semiconductor chip 2 and the sealing resin 3, and the sealing resin 3 is peeled from the semiconductor chip 2. Accordingly, the semiconductor chip 2 can be acquired under an unsealing state, and the sealing resin 3 on the upper surface side of the semiconductor chip 2 can be recovered positively as a replica 3a.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field 1] The present invention relates to a method for opening a semiconductor package such as a small resin-sealed IC package when performing failure analysis.

1 Background Art I In a semiconductor package such as an IC package, a semiconductor chip such as an IC chip is embedded in a sealing resin such as an epoxy resin. It is necessary to open the semiconductor package. Conventionally, this unsealing is generally carried out by using fuming nitric acid to dissolve all the sealing resin of the semiconductor package.

However, when opening the seal by dissolving the sealing resin using fuming nitric acid, the surface of the semiconductor chip is exposed to the strong acid fuming nitric acid, causing changes in the ion status on the surface of the semiconductor chip. There is a problem in that the surface of the semiconductor chip undergoes changes and accurate analysis may not be possible. In addition, the part of the sealing resin in contact with the top surface of the semiconductor chip is called a replica, and information for analysis such as moisture intrusion routes and resin flowability can be obtained from the surface of the replica in contact with the semiconductor chip. There is also the problem that such a replica cannot be obtained by the method of dissolving the sealed rJf fat.

[Object of the Invention] The present invention has been made in view of the above points, and provides an unsealing method for a semiconductor chip that can be opened without changing the surface condition of the semiconductor chip and can also produce a replica. The purpose is to provide a method.

[Disclosure of the Invention] According to the method for unsealing a semiconductor chip according to the present invention, the sealing resin 3 of the semiconductor package 1 is cut and removed except for the sealing resin 3 that seals the upper and lower surfaces of the semiconductor chip 2, and then the semiconductor chip is opened. The method is characterized in that the sealing resin 3 remaining on the upper and lower surfaces of the chip 2 is exposed to flame to peel off the sealing resin 3 from the semiconductor chip 2, so that the seal can be opened without the need to use fuming nitric acid. The above object has been achieved, and the present invention will be described in detail below with reference to Examples.

A semiconductor package 1 is formed as shown in FIG. 1(a) by sealing a thin plate-shaped semiconductor chip such as an IC chip with a sealing resin 3 such as an epoxy resin. Figure 1 (
, ), 5 is a lead frame. In order to open this semiconductor package 1, the position of the semiconductor chip 2 within the semiconductor package 1 is first confirmed by X-ray photography, etc., and the sealing resin 3 around the semiconductor chip 2 is cut by mechanical means. and remove it. In this way, by removing the sealing resin 3 from the semiconductor package 1 leaving the sealing resin 3 sealed on both the upper and lower surfaces of the semiconductor chip 2, the sealing resin 3 is removed from the semiconductor package 1 as shown in FIG. 1(b). A semiconductor chip 2 sandwiched between upper and lower sealing resins 3 can be cut out. In this case, it is preferable to cut out the semiconductor chip 2 so that the end face is exposed as much as possible, but since the semiconductor chip 2 is extremely susceptible to impact, it is necessary to cut out the semiconductor chip 2 with the utmost care.

After cutting out the sandwich-like material in this manner, the sandwich-like material is placed in the flame of a burner and heated for several seconds. This operation only requires that the sealing resin 3 burns for a moment; care must be taken because if the sealing resin 3 is burned too much, the strength of the sealing resin 3 will be extremely reduced.

By heating the semiconductor chip 2 with the flame of the burner in this way, thermal shock stress due to the difference in coefficient of thermal expansion between the semiconductor chip 2 and the sealing resin 3 acts between the semiconductor chip 2 and the sealing resin. The sealing resin 3 is peeled off from the semiconductor chip 2 as shown in FIG. 1(c). In this way, the semiconductor chip 2 can be unsealed and the sealing resin 3 on the upper surface side of the semiconductor chip 2 can be reliably recovered as a replica 3a. Since the surface of the semiconductor chip 2 is not affected by strong acids such as fuming nitric acid, there is no change in the surface condition and accurate analysis can be performed. In addition, since the replica 3a can be recovered in addition to the semiconductor chip 2, the replica 3a can also be recovered.
Excellent information can be obtained by analyzing a along with the semiconductor chip 2.

Although the present invention is easily applicable to small packages such as 18SOP, it goes without saying that it can also be applied to other packages such as DIP.

[Effect of the invention 1 As described above, in the present invention, the sealing resin that seals the upper and lower surfaces of the semiconductor chip is removed from the semiconductor package, and then the sealing resin that remains on the upper and lower surfaces of the semiconductor chip is removed. Since the sealing resin is peeled off from the semiconductor chip by burning the sealing resin with flame, there is no need to use fuming nitric acid to open the semiconductor chip, and accurate analysis can be performed without fear of changing the surface condition of the semiconductor chip. In addition, the sealing resin in contact with the top surface of the semiconductor chip can be peeled off from the semiconductor chip and recovered as a replica.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, and FIG.
1(a) is a perspective view of one step, FIG. 1(b) is a perspective view of another step, and FIG. 1(c) is an exploded view of still another step. 1 is a semiconductor package, 2 is a semiconductor chip, 3 is a sealing a
It is T-fat.

Claims (1)

[Claims] (1) Remove the sealing resin from the semiconductor package except for the sealing resin that seals the top and bottom surfaces of the semiconductor chip, and then heat the sealing resin remaining on the top and bottom surfaces of the semiconductor chip with flame to seal it from the semiconductor chip. A method for opening a semiconductor package characterized by peeling off the resin.