JP4395909B2 - IC package and IC chip - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an IC package that accommodates an IC chip (integrated circuit chip) that processes a high-frequency signal, such as a communication device, and more particularly to an IC package that ensures surge resistance while satisfying the high-frequency characteristics of the IC.
[0002]
[Prior art]
A conventional IC package will be described with reference to FIGS.
[0003]
FIG. 6A is an external view of a conventional IC package, and FIG. 6B is an external view of an IC chip accommodated in the IC package. 6A and 6B, 1 is a lead and 2 is a sealing resin. Reference numeral 10 denotes an IC chip, 101 denotes a pad, 102 denotes a circuit configuration area, and 103 denotes a surge prevention element.
[0004]
In the conventional IC package, the pad 101 of the IC chip 10 is connected to the lead 1 by a bonding wire and sealed with a sealing resin 2. A part of the lead 1 protrudes from the sealing resin 2, and the protruding lead 1 and the pattern on the circuit board are connected by soldering or the like for mounting.
[0005]
The target functional circuit is configured in the circuit configuration region 102 on the IC chip 10 accommodated in the IC package. In addition to this, a surge prevention element is provided so that the IC is not damaged even if a surge is input from the lead 1. 103 is formed.
[0006]
Here, the surge prevention element 103 is composed of a diode, a capacitor, a resistor, and the like and plays a role of absorbing surge energy.
[0007]
Generally, a surge input to an IC package is generated during transportation and assembly after the IC is manufactured and mounted on a circuit board. After mounting on the circuit board, a surge element is generated. Often unnecessary.
[0008]
[Problems to be solved by the invention]
However, when the surge preventing element is configured on an IC chip, there are problems as described below.
[0009]
First, since the surge preventing element occupies a relatively large area on the IC chip, the IC chip area increases. In recent years, IC design rules have been miniaturized, and the number of elements that can be accommodated per unit area has dramatically increased, and the IC chip area can be reduced. In general, since the IC cost depends on the IC chip area, the reduction of the IC chip area is a great merit in terms of cost.
[0010]
However, since the surge preventing element absorbs surge energy, it needs to have a certain size and is difficult to be miniaturized. For this reason, there is a limitation in reducing the IC chip area.
[0011]
Second, there is a problem that isolation between circuits in the IC chip deteriorates. As described above, since the IC chip is connected to the lead of the IC package by the bonding wire, and the lead protrudes from the sealing resin, it is caused by the bonding wire and the lead when the lead is connected to the pattern on the circuit board. There is an inductance component. In particular, when a high frequency signal is handled, the inductance component causes deterioration of isolation.
[0012]
FIG. 7 shows a conceptual diagram of the mechanism of isolation degradation.
[0013]
In FIG. 7, 1 is a lead, 2 is a sealing resin, 10 is an IC chip, 11 is a circuit 1, 12 is a circuit 2, and 13 is an inductance component. Here, the circuit 1 and the circuit 2 are formed on an IC chip. The inductance component 13 is the total of inductance components caused by the bonding wire and the lead. FIG. 7 shows the case where the lead is grounded, but it has impedance in terms of high frequency due to the presence of an inductance component. And since the circuit 1 and the circuit 2 are couple | bonded by the parasitic capacitance, resistance, etc. of the surge prevention element 103, the isolation between both circuits deteriorates.
[0014]
[Means for Solving the Problems]
The present invention comprises a plurality of pads arranged in a grid on one surface of an IC package base, and a plurality of pads are electrically connected by attaching a conductive sheet to one surface of the IC package base. Even if there is no surge preventing element in the chip, the surge resistance can be satisfied and the isolation between circuits in the IC chip can be increased.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
In a first aspect of the present invention, an IC package includes a plurality of pads arranged in a grid on one surface of an IC package base, and electrically connects the plurality of pads by attaching a conductive sheet to the one surface of the IC package base. It is a thing. Further, it is not necessary to provide a surge prevention element on the IC chip, and the IC chip area can be reduced. Further, since there is no coupling of each circuit in the IC chip by the surge preventing element, high isolation can be realized.
[0016]
In the second invention, in particular, the conductive sheet in the first invention is made of a heat-meltable material. According to this, the process of removing the conductive material at the time of mounting on the circuit board becomes unnecessary.
[0017]
According to a third aspect of the present invention, in the IC chip, the plurality of pads are electrically connected by attaching a conductive sheet to a surface on which the plurality of pads are formed. According to this, even with an IC chip of the type that is bare-chip mounted on a circuit board, both surge resistance and high isolation can be achieved.
[0018]
In the fourth invention, in particular, the conductive sheet in the third invention is made of a heat-meltable material. According to this, the process of removing the conductive material at the time of mounting on the circuit board becomes unnecessary.
[0020]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0021]
Example 1
A first embodiment of the present invention will be described with reference to FIG. In FIG. 1, 1 is a lead, 2 is a sealing resin, and 3 is a conductive material. The IC chip accommodated in the IC package is connected to the lead 1 by a bonding wire. The IC chip, the wire, and a part of the lead 1 are sealed with a sealing resin.
[0022]
Next, the conductive material 3 is attached to the lead 1 so as to connect the leads. Here, solder is used as the conductive material 3. Specifically, a solder wire having a high melting point (for example, 180 degrees) is used as the conductive material 3, and this is joined to the lead 1 with solder having a low melting point (for example, 140 degrees). Since the solder wire melts in the reflow process when mounted on the circuit board, there is no need to provide a process for removing the solder wire during mounting.
[0023]
The conductive material 3 can be a conductive material that dissolves in a chemical solvent. A similar surge prevention effect can be obtained by bonding the conductive material to the lead with an adhesive such as a conductive paste. Since the conductive material is removed by dissolving with a solvent after mounting on the circuit board, the connection between the leads can be reliably ensured until the mounting is completed.
[0024]
Thus, since the leads are connected to each other in the IC package of this embodiment, it is not necessary to provide a surge prevention element on the IC chip, and the IC chip area can be reduced.
[0025]
Moreover, since each circuit is not coupled by the surge preventing element, high isolation can be realized. In the case of an IC package in which the terminals of the IC package are not leads but a pad is formed on the surface of the package, the same effect can be obtained by connecting the pads with a conductive material as in the case of the leads. In addition to attaching the conductive material to the lead or pad, the conductive material may be attached by coating.
[0026]
(Example 2)
FIG. 2A is an external view showing a configuration of an IC package according to a second embodiment of the present invention.
[0027]
Moreover, FIG.2 (b) is the sectional view on the AA 'line of Fig.2 (a). 2A and 2B, 1 is a lead, 2 is a sealing resin, 4 is a frame, and 5 is a conductive paste. The frame 4 is made of a conductive material, and the leads 1 are electrically connected to each other by bonding the leads 1 and the frame 4 with the conductive paste 5.
[0028]
Further, the frame 4 can be removed from the lead 1 by dissolving the conductive paste 5 using a solvent after mounting on the circuit board. Here, solder can be used instead of the conductive paste. When solder is used, the frame can be removed from the lead during mounting on the circuit board by a reflow process.
[0029]
In the IC package of the present embodiment, the IC chip area can be reduced and high isolation can be realized as in the first embodiment. Further, since the frame is used in this embodiment, the connection between the leads and the removal after mounting can be easily performed.
[0030]
(Example 3)
FIG. 3 is an external view of the IC package as viewed from the back side. In FIG. 3, 6 is an IC package base, 7 is a pad, and 8 is a conductive sheet.
[0031]
The third embodiment relates to an IC package in which a pad is formed in a grid shape. After an IC chip is mounted on the surface of the IC package base 6, resin sealing is performed. Here, the pad of the IC chip and the pad formed on the back surface of the IC package base 6 are electrically connected.
[0032]
Next, the conductive sheet 8 is attached to the back surface of the IC package base 6. Here, the conductive sheet 8 can be a solder sheet. The solder sheet can be attached by melting a solder sheet having a high melting point (for example, 180 degrees) and bonding the solder having a low melting point (for example, 140 degrees) to a pad.
[0033]
Since a thin solder sheet is used to melt in the reflow process when mounted on the circuit board, the process of removing the solder sheet at the time of mounting is unnecessary.
[0034]
The conductive sheet 8 can be a sheet that dissolves in a chemical solvent. A similar surge prevention effect can be obtained by adhering the conductive sheet to a pad with an adhesive such as a conductive paste.
[0035]
Further, instead of attaching the conductive sheet 8 to the IC package base pad, a similar surge prevention effect can be obtained by applying a conductive paste, paint or molten solder to the back surface of the IC package base 6. .
[0036]
A similar configuration can also be adopted for an IC chip in which a pad is provided on the back surface and a bare chip is mounted on a circuit board.
[0037]
Similarly, in the configuration of the third embodiment, a surge prevention element is unnecessary on the IC chip, and both reduction of the IC chip area and high isolation can be achieved.
[0038]
Example 4
FIG. 4 is an external view showing the configuration of an embodiment 4 of the IC package according to the present invention. In FIG. 4, 1 is a lead, 2 is a sealing resin, and 9 is a ground lead.
[0039]
The IC chip is connected to the lead 1 by a wire. The IC chip, the wire, and a part of the lead 1 are sealed with a sealing resin 2. The steps up to the above are the same as in the first embodiment.
[0040]
The IC package of the fourth embodiment is characterized in that there are a plurality of leads connected to the ground when mounted on the circuit board, that is, the ground leads 9, and the ground leads 9 are connected to each other. Further, the connection between the ground leads 9 is characterized in that the connection is made near the point where the ground pattern on the circuit board and the ground lead 9 are connected when the IC package is mounted on the circuit board.
[0041]
The merit of connecting the ground lead 9 in this way is that it is possible to achieve both surge resistance and isolation between circuits in the IC chip. Hereinafter, the reason will be described with reference to FIG.
[0042]
In FIG. 5, 1 is a lead, 2 is a sealing resin, 10 is an IC chip, 11 is a circuit 1, 12 is a circuit 2, and 13 is an inductance component.
[0043]
Here, the circuit 1 and the circuit 2 are formed on an IC chip. The inductance component 13 is the total of inductance components caused by the bonding wire and the ground lead.
[0044]
The ground lead is connected in a pattern on the circuit board after being mounted on the circuit board, but is not connected during transportation and assembly. Therefore, in order to ensure the surge resistance, it is necessary to connect the ground lines of the circuit 1 and the circuit 2. In the fourth embodiment, the ground lead is connected to each other in the vicinity of the tip of the ground lead, that is, in the vicinity of a point where the circuit board and the ground lead are connected when mounted. For this reason, the ground lines are connected even before mounting. In addition, after mounting, the ground lines of the circuit 1 and the circuit 2 are grounded at one point, so that the circuit 1 and the circuit 2 do not have a common impedance. Therefore, both surge resistance and high isolation between circuits can be achieved.
[0045]
【The invention's effect】
As is apparent from the above description, according to the IC package of the present invention, the following effects can be obtained.
[0046]
Since a plurality of leads or pads are connected by a conductive material, it is not necessary to provide a surge prevention element on the IC chip, and the IC chip area can be reduced. And since it is not necessary to comprise a surge prevention element on an IC chip, there is no coupling | bonding of each circuit in IC chip, and high isolation is realizable.
[0047]
In addition, since the conductive material is composed of a heat-meltable material and the conductive material is melted when the IC package is mounted on the circuit board in the reflow process, the step of removing the conductive material after mounting is not necessary.
[0048]
In addition, the conductive material is made of a material that is soluble in the solvent, and after mounting on the circuit board, the conductive material can be dissolved and removed with the solvent to ensure the connection between the leads until the mounting is completed. be able to.
[0049]
Further, the plurality of ground leads are connected to each other at a position where the plurality of ground leads are connected to a circuit board pattern on which the plurality of ground leads are mounted, and a plurality of IC chip internal circuits configured by independent grounds Can be made to have no common impedance to each other, so that both surge resistance and isolation between circuits can be achieved.
[Brief description of the drawings]
FIG. 1 is an external view of an IC package according to a first embodiment of the present invention. FIG. 2 (a) is an external view of an IC package according to a second embodiment of the present invention. FIG. 3 is an external view of the IC package according to the third embodiment of the present invention as viewed from the back surface. FIG. 4 is an external view of the IC package according to the fourth embodiment of the present invention. FIG. 6A is an external view of an IC package of a conventional example. FIG. 6B is a block diagram showing an IC chip built in the package. FIG. 7 is a diagram illustrating the operation of the package. Configuration [Explanation of symbols]
1 Lead 2 Sealing Resin 3 Conductive Material 4 Frame 5 Conductive Paste 6 IC Package Base 7 Pad 8 Conductive Sheet 9 Ground Lead

Claims (4)

An IC package comprising a plurality of pads arranged in a grid on one surface of an IC package base and electrically connecting the plurality of pads by attaching a conductive sheet to one surface of the IC package base.   The IC package according to claim 1, wherein the conductive sheet is a heat-meltable material. An IC chip in which a conductive sheet is attached to a surface on which a plurality of pads are formed, and the plurality of pads are electrically connected.   The IC chip according to claim 3, wherein the conductive sheet is a heat-meltable material.

Images