JPH058865B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a semiconductor mounting board,
In particular, the present invention relates to a semiconductor mounting board (so-called plug-in package) on which conductor pins that can be used as input/output pins for external connection are fixed. Semiconductor mounting boards with fixed conductor pins of this type are not only widely used as semiconductor packages for computers and communication equipment that require high reliability, but also as hybrid IC boards that require high-mix, low-volume production. It is also highly used as a board for modules.

(Prior Art) Semiconductor mounting boards have become smaller as the semiconductors (so-called chips or electronic components) mounted on them have become miniaturized, and along with this, input/output pins for external connections have become smaller. The fixing intervals of conductor pins are also becoming shorter, and it is now necessary to fix these conductor pins to the board side at intervals of 100 mils (2.5 mm), and in some cases, 50 mils.

By the way, two types of conventional semiconductor mounting substrates have been widely used: those whose main materials are ceramics and those whose main materials are organic resins. Semiconductor mounting substrates made mainly of ceramic have excellent electrical insulation, moisture resistance, and heat dissipation properties due to the characteristics of ceramic, so they are suitable for use in fields that require high reliability, such as computers and communication equipment. It has been provided. However, semiconductor mounting substrates whose main material is ceramic,
Because it is manufactured through a fairly complicated process of molding powder, sintering it at high temperatures, and then fixing the conductor pins with brazing, the unit price per product is low when producing large quantities of standardized products. However, there is a problem in that the unit price per product and the process period become considerably large for high-mix, low-volume production, which has become a growing demand in recent years. Furthermore, since ceramic is a brittle material, the thickness of the substrate must be increased in order to provide sufficient mechanical strength. I can not say.

On the other hand, semiconductor mounting substrates made mainly of organic resin have excellent electrical insulation and processability due to the characteristics of the organic resin, so they are suitable for high-mix, low-volume production of non-standardized products. , which has the advantage of being inexpensive and able to supply products in a short period of time.
However, organic resins have fundamental drawbacks in that they allow moisture to pass through easily and have poor thermal conductivity, making them unsuitable for the field of high-density packaging that requires high reliability.

The biggest drawback between these materials, which are those made mainly of ceramics and those made mainly of organic resin, is that multiple conductor pins are connected at very short intervals on the board side, as mentioned in the introduction. When fixed to
In the case of ceramics, there are difficulties in processing the parts where the conductor pins are fixed (for example, high-precision soldering is difficult due to the cost, and mechanical fixation is difficult because it is necessary to avoid cracking the ceramic board). In addition, organic resins lack mechanical strength and are fragile at the locations where the conductor pins are fixed, and in any case, it is difficult to fix the conductor pins within a short distance.

(Problems to be Solved by the Invention) The present inventors have conducted extensive research to solve the above-mentioned difficulty in fixing conductor pins to base materials that are becoming smaller, and have found that metal By adopting a substrate of I was able to securely fix the pin.

An object of the present invention is to be able to securely and easily fix conductor pins within short intervals, and to prevent connection failures between through holes and each conductor pin. It is an object of the present invention to provide a substrate for mounting a semiconductor which has excellent moisture resistance, heat resistance and heat dissipation.

(Means for Solving the Problems and Their Effects) The means taken by the present invention to solve the above problems will be explained with reference to FIGS. 1 and 2, which correspond to embodiments. A metal substrate 1 having a through hole 1a, an insulating layer 2 formed on at least one surface of the metal substrate 1 and inside the through hole 1a, and a cross-sectional corner formed approximately at the center of the insulating layer 2 inside the through hole 1a. is provided with a through hole 2a having a substantially right angle, and a conductor pin 3 fixed by a support part 3a forcefully fitted into the through hole 2a, and the thickness of the insulating layer 2 is at least 50 to 500 μm. , an inorganic filler or an inorganic cloth is mixed into this insulating layer 2, and the inner diameter of the through hole 2a is connected to the conductor pin 3.
A substrate for mounting a semiconductor 1, characterized in that the outer diameter of the supporting portion 3a is in the range of 70 to 95%.
0".

Below, the semiconductor mounting substrate 10 according to the present invention will be explained in detail based on the drawings. 1 is a perspective view of the semiconductor mounting substrate 10 of the present invention, FIG. 2 is a longitudinal sectional view thereof, FIG. 6 is a plan view thereof, and FIG. 7 is a bottom view thereof.

Reference numeral 1 in FIGS. 1 and 2 indicates a metal substrate forming the main material of the semiconductor mounting substrate 10 of the present invention. When determining the material for the metal substrate 1, it is necessary to comprehensively consider various properties such as dimensional stability, thermal conductivity, specific gravity, and mechanical strength.
Typical examples of materials that comprehensively consider these are aluminum, copper, iron, or alloys thereof. In addition, the thickness of the metal substrate 1 must be selected within a range that has sufficient mechanical strength and does not conflict with the trend toward miniaturization and weight reduction of electronic devices.
It is preferably within the range of 0.5 to 0.3 mm. Furthermore, the size of the semiconductor mounting substrate 10 can be selected relatively freely by taking advantage of the good mechanical properties of the metal that constitutes it. Atatsuta 10
It is also possible to manufacture a semiconductor mounting substrate 10 having a size of cm square or larger. At first glance, increasing the size of the semiconductor mounting substrate 10 seems to go against the trend of smaller and lighter electronic devices, but increasing the size of the semiconductor mounting substrate 10 makes it possible to mount a plurality of semiconductors on one semiconductor mounting substrate 10. This makes it possible to increase the packaging density per unit area as a whole.

Reference numeral 1a in FIGS. 1 and 2 indicates a through hole previously formed in the metal substrate 1, and a through hole 2a is formed by providing an insulating layer 2 on the inner wall surface of the through hole. This insulating layer 2 may or may not have a conductor layer 4 on its surface. In other words, there are two types of shapes for the through hole 2a, and each case is classified as a third shape.
It is shown in the partial vertical cross-sectional view of FIG. The one shown in FIG. 3 has a conductor layer 4,
An insulating layer 2 is provided on the inner wall surface of the through hole 1a, and a conductor layer 4 is provided on the surface of this insulating layer 2. Furthermore, a device without the conductor layer 4 is shown in FIG.

The thickness of the insulating layer 2 needs to be within the range of 50 to 500 μm in order to satisfy both the insulation and heat dissipation properties required for the completed semiconductor mounting board 10. In addition to the case where the entire surface of the metal substrate 1 is covered with the insulating layer 2, there are cases where only one side or a desired part of the metal substrate 1 is covered in order to provide a heat dissipation effect. As the material for the insulating layer 2, it is appropriate to use a thermosetting resin from the viewpoints of electrical insulation, heat resistance, chemical resistance during circuit formation, etc. A typical example is a heat-resistant epoxy resin. , polyimide resin.

Furthermore, it is necessary to mix an inorganic filler or an inorganic cloth into the thermosetting resin constituting the insulating layer 2 for the purpose of improving thermal conductivity, conductor adhesion, and the like. Examples of inorganic fillers include α-alumina and fused silica, while examples of inorganic cloths include glass cloth. In addition, the mixing ratio of the inorganic filler is preferably large in order to improve the thermal conductivity, while it is preferably small in order to improve the surface smoothness and toughness of the insulating layer 2, and in order to satisfy both It is preferably in the range of 0 to 300 parts by weight per 100 parts by weight of the mold.

The purpose of the through hole 2a is, of course, to provide continuity between the conductor circuits 5 on the front and back sides of the board, as in a normal electronic circuit board of this type. Another purpose is to securely insert and fix the pin 3, and in that case, it goes without saying that the conductor pin 3 and the conductor circuit 5 are electrically connected. The smaller the diameter of the through hole 2a, the higher the wiring density, but if it is extremely small, it will be difficult to process, so it should be 50 to 300% of the thickness of the metal substrate 1.
It is preferable that it is in the range of .

Furthermore, since it is necessary to fit and secure the conductor pin 3 into the through hole 2a, the through hole 2a
The finished diameter of a, that is, the inner diameter, needs to be within a range of 70 to 95% of the outer diameter of the support portion 3a that constitutes a part of the conductor pin 3. The reason for this is that if the inner diameter of the through hole 2a is less than 70% of the outer diameter of the support part 3a of the conductor pin 3, it is not only difficult to fit the support part 3a into the through hole 2a, but also Even if the through hole 2a
On the other hand, if the through hole 2a has an inner diameter of 95% or more, the support part 3a of the conductor pin 3 will not fit into the through hole 2a of the metal substrate 1. This is because fixing becomes difficult.

Then, the thickness of the insulating layer 2 formed in this through hole 2a is set to 50 to 500 μm, and
An inorganic filler or an inorganic cloth must be mixed into this insulating layer 2. The reason for this is that when the conductor pins 3 are inserted and fixed into the through holes 2a, it is necessary to prevent the occurrence of poor connection between the through holes 2a and each conductor pin 3, and to improve moisture resistance. .

FIG. 3 shows a structure in which a conductor layer 4 is formed, but in this case, the inner diameter of the through hole 2a including the conductor layer 4 must be set to the above-mentioned value. On the other hand, the through hole 2a in the example shown in FIG. 4 is simply an insulating hole without the conductor layer 4, and only the insulating layer 2 is formed on the inner wall surface of the through hole 1a. be. The insulating hole shown in FIG. 4 is used, for example, when the purpose is to mount a sealed electronic component with leads in the hole, and the conductor pin 3 fixed in the hole is Since it is insulated from the conductive circuit 5 formed on the surface of the metal substrate 1, it can be used, for example, as a positioning pin necessary during mounting (input/output of signals is not required through this). The diameter of the insulating hole in this case is 50% of the thickness of the metal substrate 1, as in the case of the through hole 2a with the conductor layer 4.
The thickness of the insulating layer 2 is preferably in the range of 50 to 500 μm. Furthermore, when the conductor pin 3 is inserted and fixed into the insulation hole, the finished diameter, that is, the inner diameter of the insulation hole is within the range of 50 to 99% of the outer diameter of the support portion 3a that constitutes a part of the conductor pin 3. As mentioned above, this is necessary.

The through hole 2a is formed approximately at the center of the insulating layer 2, and its cross-sectional corner portions are approximately perpendicular. As shown in FIGS. 3 and 4, the cross-sectional corner of this through hole 2a is
It refers to corner portions formed at the upper and lower ends of the insulating layer 2 or the conductor layer 4 in a cross section that appears when the portion corresponding to the through hole 2a is cut vertically. In order to make the cross-sectional corners of the through-holes 2a substantially perpendicular, the following method is usually used.

That is, first, a through hole 1a is formed in the metal final plate 1, and an insulating material mixed with an inorganic filler or an inorganic cloth is filled into the through hole 1a.
The insulating material is applied to the required surface of the metal final plate 1 by a doctor blade method or the like to form an insulating layer. After this insulating material is cured, a hole is formed in the substantially center of the insulating material within the through hole 1a in a direction substantially perpendicular to the metal final plate 1. As a result, the cross-sectional corner of the through hole 2a without the conductor layer 4 becomes a substantially right angle. In the case of a through hole 2a having a conductor layer 4, the conductor layer 4 is formed on the inner surface of the insulating layer 2 whose cross-sectional corner portions are substantially right angles by plating, etching, or other methods in addition to the above-mentioned method. However, in this case, since the cross-sectional corners of the insulating layer 2 are already substantially right-angled, the cross-sectional corners of the conductive layer 4 plated and etched thereon are also substantially right-angled.

The reason why the insulating layer 2 is formed so that its cross-sectional corners are substantially perpendicular is that even when the insulating layer 2 alone or the conductor layer 4 is provided on the inner surface of the insulating layer 2, the through holes 2a When the conductor pin 3 is forcibly fitted, the conductor pin 3 is connected to the metal substrate 1.
This is to make it approximately perpendicular to the angle. This is because unless the conductor pins 3 are substantially perpendicular to the metal substrate 1, high-density mounting is impossible.

Reference numeral 3 in FIGS. 1 and 2 indicates a conductor pin. The conductor pins 3 are used to electrically connect the conductor circuit 5 on the semiconductor mounting board 10 of the present invention to the outside, and are used to solder the semiconductor mounting board 10 to a printed wiring board (not shown). It also serves as a mechanical reinforcing material when fixed in place. Furthermore, when this conductor pin 3 is inserted and fixed into a conductive hole that does not have an insulating layer 2 on the inner wall surface of the through hole 1a, it can be used as a thermal connection with an external heat sink and as an electrical ground. It serves to bring about connection. In order to achieve each of the above purposes of use, the material of the conductor pin 3 must have low electrical resistance, sufficient mechanical strength, and good solderability. For this reason, it is preferable to use a material whose main material is an Fe--Ni alloy, a Fe--Ni--Co alloy, or a copper-based alloy, and whose surface is suitably solder-plated or nickel-gold plated. The outer diameter of the conductor pin 3 is preferably made thin and short in order to increase the packaging density.On the other hand, it is preferable to make the conductor pin 3 thin and short in order to increase the mounting density. Considering the technical level of mounting on a board, extremely thin and short ones are not practical. Therefore, the length is 3 to 10 mm and the thickness is 0.3 mm.
It is preferable to use conductor pins 3 in the range of ~1.0 mm.

Further, the shape of the conductor pin 3 can be determined relatively freely depending on the purpose. For example, if the purpose is only to transfer input/output signals between the semiconductor mounting board 10 and the outside, the shape of the conductor pin 3 can be determined relatively freely. If the purpose is to regulate the distance between the semiconductor mounting board 10 and the printed wiring board in addition to input/output signals, it is sufficient to use a straight pin as shown in (referred to as a straight pin) It is preferable to use a pin (referred to as a standoff pin) provided with a flange-like portion as shown in FIG. 5b at a desired portion.

Further, the shape of the support portion 3a into which the conductor pin 3 is inserted into the through hole 2a is preferably such that the system is thicker than the straight portion so that the support portion 3a does not easily come out or wobble after being inserted and fixed. In order to ensure such a shape, it is necessary to have not only a spindle shape as shown in Fig. 5 a to c, but also a ladle shape as shown in Fig. 5 d, a cross shape as shown in Fig. 5 e, etc. is cited as a typical example. Furthermore, for the reason mentioned above, the finished diameter of the through hole 2a must be smaller than the maximum diameter of each of these supporting parts 3a, and as mentioned above, the finished diameter of the through hole 2a should be set to 50% of the maximum diameter of this supporting part 3a. It is necessary to keep it within the range of ~99%. Furthermore, the conductor pin 3 is inserted into the through hole 2 at the boundary between the support portion 3a and the straight portion.
It is necessary to provide a collar 3b as shown in FIGS. 5a to 5e in order to prevent the semiconductor mounting board 10 from being inserted deeply into the pin a and to obtain a semiconductor mounting board 10 having a desired pin length. When the conductor pin 3 is forcibly fitted into the through hole 2a and fixed, the collar 3b acts as a stopper to prevent the conductor pin 3 from being inserted into the metal substrate 1 to a depth greater than the required depth. There is no.

Although the shape of the flange 3b described above may be any shape, a flat circular shape is most preferable in order to evenly absorb the pressure when the flange 3b is inserted and fixed. It is necessary to determine the diameter within a range that does not impair miniaturization of the substrate 10, and the diameter is preferably in the range of 0.5 to 5 mm, and the thickness is preferably in the range of 0.2 to 2 mm.

Semiconductor mounting board 1 shown in FIGS. 1 and 6
As the material for the conductor circuit 5 formed on the surface of the 0, it is necessary to select a metal that has low conduction resistance and is easy to form a circuit, and copper is the most typical example. The conductor circuit 5 formed of copper may be further plated with solder, nickel, gold, etc. on its surface to prevent corrosion, improve solderability, or improve bonding performance. .
The thickness of the conductor circuit 5 is preferably thicker in order to reduce conduction resistance, and thinner in order to increase the wiring density of the circuit, and preferably in the range of 5 to 70 μm to satisfy both. Also, for the same reason, the width of the conductor circuit 5 is
A range of 30 to 500 μm is preferred.

The reference numeral 6 shown in FIGS. 1 and 2 is
This is a recess for mounting a semiconductor formed on at least one surface of the metal substrate 1. When a semiconductor is mounted in the recess 6, the semiconductor and the metal substrate 1
This allows the heat from the semiconductor to be transferred well to the metal substrate 1 side, and the heat generated by the mounted semiconductor to be efficiently transferred to substantially the entire semiconductor mounting substrate 10. This heat can be dissipated from substantially the entire semiconductor mounting board 10 including the conductor pins 3.

Next, an embodiment of the semiconductor mounting substrate 10 according to the present invention will be described.

(Example) The semiconductor mounting substrate 10 shown in FIGS. 1 to 3 was manufactured as follows.

Metal substrate 1 has a thickness of 1.0 mm and a size of 25 x 25
A plurality of through holes 1a are formed in aluminum and have a diameter of 1.5 mm. Further, the thickness of the insulating layer 2 formed on the front and back sides of the metal substrate 1 of the semiconductor mounting substrate 10 is 50 μm, and the thickness of the insulating layer 2 formed on the inner wall surface of the through hole 1a is 500 μm.
This insulating layer 2 is mainly made of heat-resistant epoxy resin, into which 150 parts by weight of α-alumina powder (filler) with an average particle size of 5 μm is mixed per 100 parts by weight of the solid resin. It is. The surface of the insulating layer 2 inside this through hole 1a has a thickness of 25 μm.
A conductor layer 4 is formed.

Furthermore, the conductor pin 3 is soldered with a copper alloy, and its length is 5 mm at the bottom of the collar 3b, its thickness is 0.46 mm, and the outer diameter of its support portion 3a is 5 mm.
It is 0.5mm. On the other hand, the conductor circuit 5 formed on the surface of the metal substrate 1 is formed on the surface of a copper conductor with a thickness of 35 μm.
It has 8μm nickel plating and 0.5μm gold plating on the surface.

Note that the recess 6 for mounting the semiconductor has a size of 7×7.
mm, depth 0.3mm.

The moisture resistance of the above-mentioned semiconductor mounting board 10 was examined using a temperature/humidity cycle test (MIL-STD-202F 106E), and it was found that there were no defects at the connection points between each through hole 2a and the conductor pin 3 even after 10 cycles. This did not occur, indicating good reliability.

In addition, the power IC is mounted on the semiconductor mounting board 10.
As a result of examining the heat dissipation properties of the semiconductor mounting board 10 by mounting it on a board and generating heat, the thermal resistance was found to be
The temperature was 2.0° C./W, indicating that the semiconductor mounting substrate 10 according to the present invention exhibited good heat dissipation.

The semiconductor mounting substrate 10 shown in FIGS. 1 to 3 was manufactured as follows.

Metal substrate 1 has a thickness of 0.8 mm and a size of 50 x 50
A plurality of through holes 1a are formed using mm copper.
is 1.0mm in diameter. Further, the thickness of the insulating layer 2 formed on the front and back sides of the metal substrate 1 of the semiconductor mounting substrate 10 is 100 μm, and the thickness of the insulating layer 2 formed on the inner wall surface of the through hole 1a is 300 μm. This insulating layer 2 is mainly made of polyimide resin containing glass cloth.

Furthermore, the conductor pin 3 is made of Fe-Ni-Co alloy with nickel-gold plating, and its length is 5 mm below the collar 3b, and its thickness is 0.46 mm.
The outer diameter of the support portion 3a is 0.5 mm. On the other hand, the conductor circuit 5 formed on the surface of the metal substrate 1 has a thickness of
The surface of a 50 μm copper conductor is plated with 5 μm thick nickel, and the surface is further plated with 1.0 μm thick gold.

As a result of examining the moisture resistance of the semiconductor mounting board 10 in a temperature/humidity cycle test, no defects occurred at the connection points between each through hole 2a and the conductor pin 3 even after 10 cycles, and the moisture resistance was improved. It showed good reliability.

In addition, the power IC is mounted on the semiconductor mounting board 10.
As a result of testing the heat dissipation properties by mounting the device on a PC and generating heat, the thermal resistance was 3.0°C/W, indicating good heat dissipation properties.

(Effects of the Invention) As detailed above, in the present invention, as exemplified in detail in the above embodiment, "a metal substrate 1 having a through hole 1a, and at least one surface of this metal substrate 1 and a through hole." An insulating layer 2 formed in the through hole 1a, a through hole 2a formed approximately at the center of the insulating layer 2 in the through hole 1a and having a substantially right-angled cross-sectional corner, and a support portion 3a forcefully fitted into the through hole 2a. The thickness of the insulating layer 2 is at least 50 to 500 μm, and an inorganic filler or an inorganic cloth is mixed in the insulating layer 2. Connect the inner diameter to conductor pin 3
It is characterized by the fact that it is formed in a range of 70% to 95% of the outer diameter of the supporting part 3a, which solves the difficulty of fixing conductor pins to base materials that are becoming smaller. The mounting board 10 can be provided with a simple configuration.

Further, according to the semiconductor mounting board 10 according to the present invention, the conductor pins 3 can be reliably and easily fixed at substantially right angles within a short interval on the metal board 1.

Further, since the semiconductor mounting substrate 10 is mainly made of metal, it has excellent heat resistance and good heat dissipation. Furthermore, since the metal substrate 1 has good workability and high mechanical strength, it is possible to supply inexpensive and thin semiconductor mounting substrates in a short period of time.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a semiconductor mounting board according to the present invention, FIG. 2 is a vertical cross-sectional view taken along the - line in FIG. 1, and FIG. FIG. 4 is a partial longitudinal sectional view corresponding to FIG. 3 without a conductor layer, and FIG. b is a front view of the conductor pin, c to e of FIG. 5 are partial perspective views of the conductor pin, FIG. 6 is a plan view of the semiconductor mounting board, and FIG. 7 is a bottom view of the semiconductor mounting board. Explanation of symbols, 10... Semiconductor mounting board, 1...
...Metal substrate, 1a... Through hole, 2... Insulating layer, 2
a...Through hole, 3...Conductor pin, 3a...
Support part, 4... Conductor layer, 5... Conductor circuit, 6...
recess.

Claims (1)

[Scope of Claims] 1. A metal substrate having a through hole, an insulating layer formed on at least one surface of the metal substrate and inside the through hole, and an insulating layer formed approximately at the center of the insulating layer inside the through hole. a through hole whose cross-sectional corner is approximately right angle;
A conductor pin is fixed by a support part that is forcibly fitted into the through hole, and the thickness of the insulating layer is at least 50 to 500 μm, and an inorganic filler or an inorganic cloth is mixed in the insulating layer. The substrate for mounting a semiconductor, further characterized in that the inner diameter of the through hole is formed to be within a range of 70 to 95% of the outer diameter of the support portion of the conductor pin. 2. The semiconductor mounting substrate according to claim 1, wherein a conductor layer is formed on the insulating layer in the through hole.