JPH0870017A - Double-sided substrate and electrode connection using both-sided substrate - Google Patents

Abstract

PURPOSE: To stabilize electrode connection quality of a both-sided substrate so as to improve its yield. CONSTITUTION: This both-sided substrate is provided with a metal plate which is a good heat-conducting body and a pre-preg 11 to be laminated on both surfaces of the metal plate 10 for forming a circuit pattern 12 on its surface while being,constituted that a projection part 10a of the metal plate 10 projects from an end face of the pre-preg 11. Thereby, heat for electrode connection can be efficiently supplied to an electrode pad of a semiconductor device 16, which is an electrode connection spot, and a circuit pattern 12 through the projection part 10a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a double-sided board on which a semiconductor device or electronic parts are mounted and an electrode connecting method using the double-sided board.

[0002]

2. Description of the Related Art An example in which bare chip semiconductor devices are mounted on both sides of a double-sided substrate will be described with reference to FIG. FIG. 7 is a cross-sectional view showing a state in which the double-sided substrate is fixed on a pedestal and electrodes are connected by wire bonding. In the figure, 1 is a double-sided substrate, 2 is a bare chip-shaped semiconductor device mounted on the first surface of the double-sided substrate 1 (the surface on the side in contact with the upper surface of the pedestal),
3 is a circuit pattern, 4 is a bonding wire, 5 is a sealing coat for sealing the semiconductor device 2, 6 is a second side of the double-sided substrate 1.
A bare chip semiconductor device mounted on the surface (the surface opposite to the first surface), 7 is a pedestal for supporting the double-sided substrate 1 at the time of wire bonding, and 7a is a concave shape formed on the upper surface of the pedestal 7. The counterbore portion 8 is a holding jig for contacting the surface of the double-sided substrate 1 and fixing and positioning the double-sided substrate 1 on the pedestal 7.

Conventionally, in the case where bare chip mounting (chip on board, COB) is performed on both surfaces of the double-sided substrate 1, first, the semiconductor device 2 is die-bonded to the first surface of the double-sided substrate 1, and the semiconductor is bonded by the bonding wire 4. After electrode connection between the electrode pad (not shown) of the device 2 and the circuit pattern 3 on the first surface, the semiconductor device 2 is sealed by a potting method in which a liquid resin such as epoxy is poured and cured. Next, the first surface of the double-sided substrate 1 was faced to the back side, and the semiconductor device 6 was die-bonded to the second surface for electrode connection. Here, when the electrodes are connected by the bonding wires 4, a gold wire is generally used, and the ultrasonic wave and thermocompression bonding are used together. When wire bonding is performed, the temperature of the connection point is raised in advance, but the heat necessary for raising the temperature is supplied to the double-sided substrate 1 from the pedestal 7 that supports the double-sided substrate 1. The pedestal 7 has a heater block (not shown) as a heat source.
Is provided.

In order to perform wire bonding on the second surface side of the double-sided substrate 1, when the double-sided substrate 1 is placed on the pedestal 7 with the first surface side of the double-sided substrate 1 facing downward, the sealing coat of the semiconductor device 2 is formed. Since 5 is raised like a glove top,
A recessed spot facing portion 7a is formed so that the pedestal 7 and the sealing coat 5 do not come into contact with each other. As the material of the base material of the double-sided substrate 1, epoxy and polyimide resins have been mainly used.

[0005]

However, since the bare chip mounting of the semiconductor device on both sides of the conventional double-sided substrate has been performed as described above, it is necessary to connect the electrodes of the semiconductor device on the second side. Heat supply was difficult. This is because the heat conduction efficiency is poor due to the air layer (gap) in the spot facing portion 7a, and the heat is transferred to the double-sided substrate 1 from the contact surface of the pedestal 7 around the spot facing portion 7a with the double-sided substrate, and the heat is transferred. The heat was conducted in a considerably detoured route such as being conducted to the semiconductor device 6 or the circuit pattern 3 that is electrode-connected to the semiconductor device 6. Therefore, the semiconductor device 6 or the semiconductor device 6
In order to raise the temperature of the circuit pattern 3 connected to the electrode to a desired temperature, it is necessary to raise the set temperature of the heater block which is the heat source to apply excessive heat to the pedestal 7. However, if excessive heat is applied to the pedestal 7, there is a problem that the circuit pattern 3 is peeled off or the double-sided board 1 is warped. In addition to the semiconductor device 2, electronic components (chip capacitors, resistors, etc.) may be mounted by soldering on the first surface on the back side of the double-sided substrate 1,
Thermal stress is applied to the solder, cracking the solder,
It was also a cause of peeling and the like. Furthermore, as a matter of course, the melting point of the solder had to be selected to be higher than the set temperature of the pedestal by several tens of degrees, so that the eutectic solder has a low melting point but strong bonding strength and good heat cycle property. There was also a problem that (for example, Pb37% Sw) could not be used.

Further, in the spot facing portion 7a of the pedestal 7, since the double-sided substrate 1 is not directly supported by the pedestal 7, the electrode pad of the semiconductor device 6 and the circuit pattern 3 on the double-sided substrate 1 are ultrasonically bonded by wire bonding. When attempting to connect by thermocompression bonding, the ultrasonic energy is not transmitted to the joint portion due to the bending or vibration (boundary) of the double-sided substrate 1,
There is a problem that the electrode bonding quality is extremely poor.

The present invention has been made in view of the above problems. An object of the present invention is to mount the semiconductor device or the electronic component on the first surface and the electrode connection quality of the semiconductor device mounted on the second surface on the back side thereof. Stable and improved yield, enabling low-cost bare-chip mounting on both sides of the substrate, which leads to downsizing of equipment and structure of double-sided board and electrode connection method using the double-sided board. To provide.

[0008]

In order to achieve the above object, the double-sided board according to claim 1 is a plate-shaped good heat conductor,
An insulating layer laminated on both sides of the good thermal conductor and having a circuit pattern formed on the surface thereof, wherein a part of the good thermal conductor projects from an end face of at least one of the insulating layers. It is what

A double-sided board according to a second aspect comprises a plate-shaped good heat conductor and an insulating layer laminated on both surfaces of the good heat conductor and having a circuit pattern formed on the surface thereof. At least one of them has a through hole reaching from the front surface to the back surface of the insulating layer, and the good thermal conductor is exposed through the through hole.

A double-sided board according to a third aspect of the present invention comprises a copper-clad laminate and an insulating layer laminated on both sides of the copper-clad laminate and having a circuit pattern formed on the surface thereof, and at least one of the insulating layers. Further, a through hole reaching from the front surface to the back surface of the insulating layer is formed, and the circuit pattern of the copper clad laminate is exposed through the through hole.

A double-sided substrate according to a fourth aspect is the double-sided substrate according to the first or second aspect, in which at least one of the insulating layers has a through hole for mounting a semiconductor device that extends from the front surface to the back surface of the insulating layer. The bare chip semiconductor device is bonded to the good thermal conductor inside the through hole for mounting the semiconductor device.

A double-sided board according to a fifth aspect is the double-sided board according to the third aspect, in which at least one of the insulating layers has a through hole for mounting a semiconductor device which extends from a front surface to a back surface of the insulating layer, In the semiconductor device mounting through hole, a bare chip-shaped semiconductor device is bonded onto a circuit pattern formed on the copper clad laminate.

The double-sided board according to claim 6 is the double-sided board according to claim 1, 2 or 4, wherein the exposed portion of the good thermal conductor is heated and mounted on the double-sided board. It is characterized in that heat is supplied for connecting electrodes of semiconductor devices and other electronic components.

The double-sided board according to claim 7 is the double-sided board according to claim 3 or 5, wherein the exposed circuit pattern of the copper-clad laminate is heated to be mounted on the double-sided board. Another feature is that heat is supplied to connect electrodes of other electronic components.

[0015]

The double-sided board of the present invention is characterized in that a good heat conductor such as a metal plate or a copper clad laminate is sandwiched inside the double-sided board as an inner layer of the double-sided board. Accordingly, when the semiconductor device is mounted on the second surface of the double-sided substrate on which the semiconductor device, the electronic component, etc. are already mounted on the first surface and electrode connection such as wire bonding is performed, the heat supply necessary for the wire bond is not generated. Since the circuit pattern formed on the good heat conductor of the inner layer or the copper clad laminate can be heated by the external heat source, excessive heating of the double-sided substrate is not required, and the semiconductor device, It is possible to significantly reduce the thermal stress applied to electronic components, double-sided boards and the like. Also,
Due to the properties of a good thermal conductor or copper clad laminate sandwiched (or embedded) as the inner layer, the mechanical strength is significantly improved and it becomes resistant to bending, so that the deflection, vibration, warpage, etc. of the double-sided board at the time of connecting the electrodes of the semiconductor device. Therefore, stable wire bonding or the like (including thermocompression bonding only by heating or a bonding method only by applying ultrasonic waves) is possible.

[0016]

EXAMPLE An example of the double-sided board of the present invention will be described with reference to FIG. FIG. 1 is a sectional view showing a state in which a double-sided substrate is fixed on a pedestal and wire bonding is performed.
In the figure, 9 is a double-sided substrate. The double-sided substrate 9 includes a metal plate 10 that is a plate-shaped good heat conductor, a prepreg 11 that is an insulating layer laminated on both surfaces of the metal plate 10, and a prepreg 1.
1 and the circuit pattern 12 formed on the surface thereof. Reference numeral 13 is a bare chip semiconductor device mounted on the first surface of the double-sided substrate 9, 14 is a bonding wire, 15 is a sealing coat for sealing the semiconductor device 13 and the bonding wire 14, and 16 is a second surface of the double-sided substrate 9. A bare chip semiconductor device mounted on the base 17; a pedestal 17 for supporting the double-sided substrate 9 during wire bonding;
Is a holding jig for fixing and positioning the double-sided substrate 9 on the pedestal 17 by abutting on the surface of the.

In the double-sided board 9 shown in FIG. 1, a part of the metal plate 10 projects from the end face of the prepreg 11 to form a projecting portion 10a. The pedestal 17 is formed with a concave substrate supporting portion 17a for supporting the first surface of the double-sided substrate 9, and a counterbore portion 17b for preventing contact between the pedestal 17 and the sealing coat 15 is formed on the substrate. It is formed on the bottom surface of the support portion 17a. In the board supporting portion 17a, the double-sided board 9 is the pedestal 17
The depth is set so that the first surface of the double-sided substrate 9 comes into contact with the bottom surface of the substrate supporting portion 17a and the surface of the pedestal 17 comes into contact with the metal plate 10 when the upper surface is placed above.

The metal plate 10 is generally made of copper, Al, Fe, kovar, or black oxide whose surface is roughened in order to increase the adhesion with the prepreg 11 serving as an insulating layer. A copper plate or the like having a second copper layer formed on its surface is used.

The double-sided substrate 9 is formed, for example, by sandwiching a metal plate 10 between prepregs 11 and heating and pressing. Here, the double-sided board 9 is configured such that a part of the inner layer metal plate 10 projects from the end surface of the prepreg 11 to form a projecting portion 10 a. In the embodiment shown in FIG. 1, the protrusion 10a
At this location, both the front and back surfaces of the metal plate 10 are exposed. When a through hole (not shown) is provided to connect the circuit pattern formed on the first surface of the double-sided board 9 and the circuit pattern formed on the second surface, the metal plate 10 is provided. It suffices to make a cut portion or a hole at a position where a through hole is to be formed in advance. After laminating the prepreg 11 on the metal plate 10, a general through hole forming method (a method of filling a hole with ing). ) Or a tenting method (method using a dry film) or the like.

The metal plate 10 is constructed as described above.
By supplying heat to the exposed protruding portion 10a for electrode connection (wire bond, soldering, etc.) of the semiconductor device or other electronic component, heat can be efficiently transmitted to the joint portion of the electrode connection. Therefore, stable electrode connection can be performed without applying thermal stress to the double-sided board 9 or the solder. Further, eutectic solder (for example, Pb37% Sw) having a low melting point but a high bonding strength and good heat cycle property can be used.

A different embodiment of the double-sided board of the present invention will be described with reference to FIG. However, the same components as those shown in FIG. 1 are designated by the same reference numerals. The difference between the embodiment shown in FIG. 2 and the embodiment shown in FIG.
Does not project from the end surface of the prepreg 19 and is a metal plate 10.
The surface of the metal plate 10 on the first surface side is covered with the prepreg 19, and the metal plate 10 projects from the end surface of the prepreg 20.
Is partially exposed to the second surface side, and the exposed surface of the metal plate 10 on the second surface side is in contact with the metal holding jig 18, and the pedestal 21 has a concave shape. Substrate support 17
The point a is not provided, and the first surface of the double-sided substrate 9 is in contact with the surface of the pedestal 21. 21a is a spot facing portion. By thus configured and transmitting heat to the metal plate 10 via the pressing jig 18, the same effect as that of the embodiment shown in FIG. 1 can be obtained.

A further different embodiment of the double-sided board of the present invention shown in FIG. 3 is the reverse of the embodiment shown in FIG.
2 shows a configuration in which an electrode is connected to the double-sided substrate 9 configured such that the surface of the protruding portion 10a of the metal plate 10 is exposed on the first surface side. That is, the embodiment shown in FIG.
The difference from the embodiment shown in FIG. 1 is that the surface on the second surface side of the metal plate 10 is covered with the prepreg 22, and only the surface on the first surface side of the protruding portion 10a of the metal plate 10 is exposed. 17 is in contact with the surface of the double-sided board 9, and the holding jig 18 is in contact with the surface of the double-sided board 9 on the second surface side. In this case,
Heat is transferred to the metal plate 10 via the pedestal 17 as in the embodiment shown in FIG.

A different embodiment of the double-sided board of the present invention will be described with reference to FIG. The embodiment shown in FIG.
The difference from the embodiment shown in FIG. 1 is that the metal plate 10 is not provided with a protrusion, and that the prepreg 2 which is an insulating layer laminated on the second surface side of the metal plate 10 has the prepreg 2.
The point is that a through hole 23a is formed so as to penetrate from the front surface to the back surface of No. 3. However, the through hole 23a is not limited to the embodiment and may be formed in the prepreg on the first surface side. By configuring as shown in FIG. 4, a part of the metal plate 10 is exposed to the second surface side of the double-sided substrate 9 at the through hole 23a, so that the exposed metal plate 10 inside the through hole 23a is heated. The heat can be transferred to the metal plate 10 by adding. The circuit pattern 12 or the semiconductor device 1 formed on the surface of the double-sided substrate 9 by heating from the metal plate 10.
The heat distribution transferred to 6 becomes uniform. That is, the double-sided board 9
The temperature difference on the surface of the electrode becomes small, and stable electrode connection becomes possible.

A different embodiment of the double-sided board of the present invention will be described with reference to FIG. The embodiment shown in FIG. 5 is different from the embodiment shown in FIG. 4 in that the insulating substrate 24 (glass epoxy, polyimide, etc.) bonded to the second surface side of the double-sided substrate 9 with an adhesive or a resin as an insulating layer. A through hole (semiconductor device mounting through hole 24a) for housing the semiconductor device 16 is formed in the resin substrate), and the semiconductor device 16 is die-bonded to the metal plate 10 inside the semiconductor device mounting through hole 24a. That is the point. By thus configuring and heating the metal plate 10 through the through hole 24b, heat can be efficiently transmitted to the semiconductor device 16 or the circuit pattern 12. After the electrodes are connected, it is better to fill the through holes 24b used for heating with a resin or the like to improve the moisture resistance, but it is not necessary to fill the holes. By mounting the semiconductor device 16 as shown in FIG. 5, the mounting height can be reduced. Further, the difference in height between the electrode pad (not shown) of the semiconductor device 16 and the circuit pattern 12, which is the electrode connection point, becomes small, and the wire loop of the bonding wire 14 is not subjected to excessive stress, so that wire bonding There is also an advantage that the yield is improved.

A different embodiment of the double-sided board of the present invention will be described with reference to FIG. In the embodiment shown in FIG. 6, an insulating substrate 2 in which a copper clad laminate 25 is used as an inner layer of a double-sided substrate instead of the metal plate 10 and a through hole 26a for heating is formed
6 is attached to the first surface side of the copper clad laminate 25, and the through hole 2
The insulating substrate 27 having 7a formed thereon is attached to the second surface side of the copper clad laminate 25, and the circuit pattern 28 formed on the second surface side of the inner copper clad laminate 25 is heated through the through holes 27a. In this embodiment, the heat is transferred to the insulating substrate 27. Although illustration is omitted, in the case of connecting the circuit pattern 28 formed on the copper clad laminate 25 and the circuit pattern 12 formed on the insulating substrates 26 and 27 bonded together, through holes or via holes are used. It suffices to connect them electrically.

In the case of the embodiment shown in FIG. 6, when connecting the electrodes of the semiconductor device 13 mounted on the first surface of the double-sided board 9, the first surface of the copper clad laminate 25 exposed in the through hole 26a is exposed. Insulating substrate 26 by heating circuit pattern 29 formed on the side
When heat is transmitted to the semiconductor device 16 to connect the electrodes of the semiconductor device 16 mounted on the second surface side of the double-sided board 9, the circuit pattern 28 formed on the second surface side of the copper clad laminate 25 exposed in the through hole 27a. To transfer heat to the insulating substrate 27.
Since heat applied to one surface is less likely to be transferred to the other surface, there is an advantage that the thermal influence on the other surface can be reduced.

A metal plate which is a good heat conductor, or
The method of heating the copper clad laminate is not limited to the method of transmitting heat by directly contacting the heat transfer member with the metal plate or the copper clad laminate, and is a non-contact method using light YAG laser, A method such as light beam or infrared heating may be used, or
The contact method such as pulse heating, hot ram, or parallel gap method may be used. Further, the shape or material of the double-sided substrate is not limited to the embodiment. further,
In the embodiment, the semiconductor device mounted on the first surface side of the double-sided board is provided with the sealing coat. However, when the bare chip of the sensor element such as the infrared detection element or the pyroelectric element is mounted on the board, it is sealed. In some cases, a stop coat may not be applied, which is not limited to the examples.

[0028]

The double-sided substrate according to any one of claims 1 to 5,
Alternatively, according to the electrode connecting method of claim 6 or 7, a bare chip-shaped semiconductor device or electronic component can be mounted at a desired position on the double-sided substrate, the electrode connection quality of the semiconductor device or the like is stabilized, and the yield is improved. To do. In addition, heat applied to the connection part of the semiconductor device or the semiconductor device mounted on the surface opposite to the surface on which the electronic component is mounted, or the other electronic component mounted by soldering. Stress can be extremely reduced, due to cracking or peeling due to deterioration of the sealing resin or solder material of the sealing coat, and diffusion of metal (mainly Au) in the wire bond joint (prominent at 150 ° C or higher) This has the effect of preventing the occurrence of defects such as strength deterioration. Therefore, it is possible to mount a low-cost bare chip on both surfaces of the substrate, and it is expected that the density and size of the device can be increased accordingly.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a double-sided board of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the double-sided board of the present invention.

FIG. 3 is a sectional view showing still another embodiment of the double-sided board of the present invention.

FIG. 4 is a sectional view showing still another embodiment of the double-sided board of the present invention.

FIG. 5 is a sectional view showing still another embodiment of the double-sided board of the present invention.

FIG. 6 is a sectional view showing still another embodiment of the double-sided board of the present invention.

FIG. 7 is a cross-sectional view showing an example of a conventional double-sided board.

[Explanation of symbols]

9 Double-sided substrate 10 Metal plate (good thermal conductor) 11, 19, 20, 22, 23, 24 Prepreg (insulating layer) 12 Circuit pattern 13, 16 Semiconductor device 23a, 24b, 26a, 27a Through hole 24a For mounting semiconductor device Through hole 25 Copper clad laminate 26,27 Insulating substrate (insulating layer) 28,29 Circuit pattern

Claims (7)

[Claims] 1. A plate-shaped good heat conductor, and an insulating layer laminated on both surfaces of the good heat conductor and having a circuit pattern formed on the surface thereof. At least a part of the good heat conductor is provided. A double-sided board, characterized in that it projects from an end face of one of the insulating layers. 2. A plate-shaped good heat conductor, and an insulating layer laminated on both surfaces of the good heat conductor and having a circuit pattern formed on the surface thereof, wherein at least one of the insulating layers has the insulating layer. A double-sided board, wherein a through hole reaching from the front surface to the back surface of the layer is formed, and the good thermal conductor is exposed through the through hole. 3. A copper-clad laminate, and an insulating layer laminated on both surfaces of the copper-clad laminate and having a circuit pattern formed on the surface thereof. At least one of the insulating layers has a surface of the insulating layer. A double-sided board characterized in that a through hole reaching the back surface is formed, and the circuit pattern of the copper clad laminate is exposed through the through hole. 4. A through-hole for mounting a semiconductor device, which reaches from a front surface to a back surface of the insulating layer, is formed in at least one of the insulating layers, and a semiconductor device having a bare chip shape inside the through-hole for mounting the semiconductor device. The double-sided board according to claim 1 or 2, wherein is bonded to the good thermal conductor. 5. A semiconductor device mounting through-hole that extends from the front surface to the back surface of the insulating layer is formed in at least one of the insulating layers, and a bare chip-shaped semiconductor device is provided inside the semiconductor device mounting through-hole. The double-sided board according to claim 3, wherein is bonded on a circuit pattern formed on the copper-clad laminate. 6. The heat supply for heating an exposed portion of the good thermal conductor to connect electrodes of a semiconductor device mounted on the double-sided substrate and other electronic components. An electrode connecting method using the double-sided substrate according to claim 1 or claim 2 or claim 4. 7. The exposed circuit pattern of the copper clad laminate is heated to supply heat for connecting electrodes of a semiconductor device mounted on the double-sided substrate and other electronic components. An electrode connecting method using the double-sided substrate according to claim 3 or 5.