JPH04245461A - Glass sealed semiconductor package - Google Patents

Abstract

PURPOSE:To prevent the occurrence of drawing cavities and voids in a sealing section and, at the same time, to prevent the displacement and deformation of a lead frame at the time of melting a low-melting point glass layer. CONSTITUTION:After a base-side high-melting point glass layer 10 is formed by printing on the outer periphery of a ceramic base 1, a lead frame 3 is stuck to the layer 10. After sticking the frame 3, a base-side low-melting point glass layer 11 is formed on the outer peripheral section of the layers 10. Then a lid-side high-melting point glass layer 12 and lid-side low-melting point glass layer 13 are successively formed by printing on a ceramic lid 6. Thereafter, the glass layers 11 and 13 are stuck to each other by fusion for sealing.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a glass-sealed semiconductor package, and more particularly, a ceramic base containing a semiconductor chip is covered with a ceramic lid, and the space between the two is sealed by glass fusing. This invention relates to a glass-sealed semiconductor package.

0002

2. Description of the Related Art FIG. 3 shows a conventional glass-sealed semiconductor package, in which a low melting point glass layer 2 is printed around the outer periphery of a ceramic base 1. A lead frame 3 is fused. An IC chip 4 is housed in the center of the ceramic base 1, and the IC chip 4 and the lead frame 3 are bonded to each other by bonding wires 5. A low melting point glass layer 7 is printed on the outer periphery of the ceramic lid 6. These ceramic base 1 and ceramic lid 6 are heated in a sealing furnace with the low melting point glass layers 2 and 7 pressed together, and the low melting point glass layers 2 and 7 are heated in a sealing furnace.
It is sealed by fusion bonding.

0003

[Problems to be Solved by the Invention] However, the low melting point glass layer 2 of the conventional glass-sealed semiconductor package described above
Since it is necessary to achieve both the functions of fixing the lead frame 3 and sealing the package, it is necessary to make it relatively thick, resulting in uneven printing and poor surface flatness. Further, when the low melting point glass layers 2 and 7 are fused together, a relatively large amount of gas is generated from the bonding paste, which tends to create high pressure inside the package. Due to the non-uniformity of the printing of the low melting point glass layer 2 and the generation of a large amount of gas from the bonding paste, conventional glass-sealed semiconductor packages have internal parts inside the sealing area after sealing, as shown in FIG. There was a problem in that sink marks 8 and internal voids, that is, internal voids 9, were likely to occur, resulting in frequent seal failures.

Furthermore, since the low melting point glass layer 2 is relatively thick as mentioned above, the low melting point glasses 2 and 7 in a molten state flow due to heating and pressure contact between the low melting point glass layers 2 and 7 during package sealing. This also causes the problem that the lead frame 3 is displaced and deformed, which adversely affects the bonding wire 5.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a glass-sealed semiconductor package that can prevent sealing defects and also prevent displacement and deformation of a lead frame when a low melting point glass layer melts. It is in.

[0006]

[Means for Solving the Problems] In order to achieve this object, a glass-sealed semiconductor package according to the present invention includes a ceramic base, a central portion of the ceramic base, and a ceramic base. a base-side high-melting-point glass layer laminated in an annular shape surrounding the base-side high-melting-point glass layer, a lead frame bonded onto the base-side high-melting-point glass layer, and the base-side high-melting point glass layer to which the lead frame is bonded. , a base-side low-melting glass layer laminated in an annular shape surrounding the center of the ceramic base, a ceramic lid covered with the ceramic base, and a ceramic lid that covers the ceramic base. The lid side low melting point glass layer is laminated in an annular shape around the outer periphery and is fused to the base side low melting point glass layer.

[0007] Among the above configurations, desirable aspects are as follows. A lid side high melting point glass layer is interposed and laminated between the ceramic lid and the lid side low melting point glass layer. The base-side low-melting point glass layer is laminated on at least a portion of the base-side high-melting point glass layer excluding an inner peripheral portion so as not to contact the bonding wire bonded to the lead frame.

[0008]

[Operation] The glass layer on the ceramic base is composed of a base side high melting point glass layer and a base side low melting point glass layer. This base side high melting point glass layer plays a role of fixing the lead frame, while the base side low melting point glass layer plays a sealing role together with the lid side low melting point glass layer. By forming the glass layer on the ceramic base side into a two-layer structure in this way, the base-side low melting point glass layer can be made relatively thin and its flatness can be improved.

Furthermore, the base-side low-melting point glass layer is laminated only on a part of the base-side high-melting point glass layer, and the laminated area can be made smaller than in the past. The occurrence of sink marks is reduced. The base-side low-melting glass layer can be made relatively thin, so it has little fluidity even when heated and pressurized during package sealing, and since the base-side high-melting glass layer fixes the lead frame, the base side and lid Displacement and deformation of the lead frame, which tends to occur when the side low melting point glass layer is fused and sealed, is suppressed.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a glass-sealed semiconductor package according to the present invention will be described below with reference to FIGS. 1 and 2, in which the same parts as in FIGS. 3 and 4 are denoted by the same reference numerals. Figure 1
A base-side high melting point glass layer 10 is printed on the outer periphery of a ceramic base 1, and a lead frame 3 is attached to this base-side high melting point glass layer 10 by passing through a furnace.
are fused. There is an IC in the center of the ceramic base 1.
A chip 4 is accommodated therein, and this IC chip 4 and lead frame 3 are bonded together by bonding wires 5.

A base-side low-melting-point glass layer 11 is printed on the base-side high-melting-point glass layer 10 to which the lead frame 3 is fused. Specifically, in order to prevent the base-side low-melting glass layer 11 from coming into contact with the bonding portion between the lead frame 3 and the bonding wire 5, the base-side high-melting-point glass layer 10 is removed except for the inner peripheral portion thereof. It is done in the area where the

A lid side high melting point glass layer 12 is printed on the outer periphery of the ceramic lid 6, and a lid side low melting point glass layer 13 is printed on this lid side high melting point glass layer 12. The thickness of the base side and lid side low melting point glass layers 11 and 13 is determined to be sufficiently thinner than the conventional low melting point glass layers 2 and 7 shown in FIG. The glasses 11 and 13 can fill in the irregularities on the surfaces of the high melting point glass layers 10 and 12, thereby improving the flatness of their own surfaces.

These ceramic base 1 and ceramic lid 6 are heated in a sealed furnace with the base side and lid side low melting point glass layers 11 and 13 pressed together, as shown in FIG. The low melting point glass layers 11 and 13 are fused together for sealing. At this time, since the surfaces of the base-side and lid-side low-melting glass layers 11 and 13 each have good flatness, the occurrence of internal cavities in the seal portion is greatly suppressed. In addition, since the laminated area of the base-side low melting point glass layer 11 that is melted during sealing is smaller than in the past,
The occurrence of internal sink marks due to an increase in internal pressure due to decomposition gas of the bonding paste is also sufficiently suppressed. Furthermore, since the base side and lid side low melting point glass layers 11 and 13 are relatively thin and have a small laminated area, their fluidity is low even when subjected to heat and pressure during sealing. Since the lead frame 3 is fixed, there is no possibility of displacement of the lead frame 3 due to the heating and pressurization during the sealing process.
Deformation can be kept sufficiently small.

[0014]

[Effects of the Invention] As is clear from the above description, the glass-sealed semiconductor package according to the present invention includes a ceramic base, an outer periphery of the ceramic base, and a central portion of the ceramic base that surrounds the ceramic base. A base-side high melting point glass layer laminated in an annular shape as shown in FIG. a base-side low melting point glass layer laminated in an annular shape surrounding the center of the ceramic base, a ceramic lid covered with the ceramic base, and a ceramic lid around the outer periphery of the ceramic lid. Since the lid side low melting point glass layer is laminated in an annular shape and is fused to the base side low melting point glass layer, the base side low melting point glass layer is relatively thin and its laminated area is made small. This makes it possible to suppress the occurrence of internal sink marks and internal voids in the sealing part, and to obtain good sealing performance.

Furthermore, since the lead frame is bonded onto the base side high melting point glass layer and the base side low melting point glass layer can be made relatively thin, the base side low melting point glass layer and the base side low melting point glass layer are bonded to each other. Displacement and deformation of the lead frame that tends to occur during fusion sealing with the lead frame can be sufficiently reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a glass-sealed semiconductor package according to the present invention.

FIG. 2 is a sectional view showing the sealed state of the above embodiment.

FIG. 3 is a cross-sectional view showing a conventional glass-sealed semiconductor package.

FIG. 4 is a plan view showing a conventional glass-sealed semiconductor package.

[Explanation of symbols]

1 Ceramic base 3 Lead frame 6 Ceramic lid 10 Base side high melting point glass layer 11 Base side low melting point glass layer 12 Lid side high melting point glass layer 13 Lid side low melting point glass layer

Claims (3)

[Claims] 1. A ceramic base; a base-side high melting point glass layer laminated around the outer periphery of the ceramic base in an annular shape so as to surround the center portion of the ceramic base; A lead frame bonded onto the melting point glass layer and a part of the base side high melting point glass layer to which this lead frame is bonded are laminated in an annular shape so as to surround the central portion of the ceramic base. A base-side low-melting glass layer, a ceramic lid covered with the ceramic base, and a lid-side low-melting glass layer laminated in an annular shape around the outer periphery of the ceramic lid and fused to the base-side low melting glass layer. A glass-sealed semiconductor package characterized by comprising a melting point glass layer. 2. The glass-sealed semiconductor package according to claim 1, wherein a lid side high melting point glass layer is interposed and laminated between the ceramic lid and the lid side low melting point glass layer. . 3. The base-side low-melting point glass layer is laminated on at least a portion of the base-side high-melting point glass layer excluding an inner peripheral portion so as not to contact the bonding wire bonded to the lead frame. The glass-sealed semiconductor package according to claim 1, characterized in that: