JP2003017611A - Circuit board with pin and electronic device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board with a pin capable of normally connecting an electronic component to be mounted to an external electric circuit without easily taking a lead pin, and to provide an electronic device. SOLUTION: The circuit board with the pin comprises a pad 2b with the pin electrically connected to a wiring conductor 2 provided on a lower surface of an insulating base 1 made of an organic material having the conductor 2, and the lead pin 3 made of a copper alloy and having a substantially truncated conical large-diameter part 3b formed at an upper end of a substantially columnar shaft 3a and stood via a solder 9 interposed between the part 3b and the pad 2b. In this case, 2.4<=A/B<=4.4 is satisfied, wherein A is a diameter of the part 3b, and B is a thickness of the part 3b, and a side face of the part 3b has an angle of 20 to 45 deg. to a direction of the shaft 3a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board with pins used for mounting electronic parts such as semiconductor elements, and an electronic device having the electronic parts such as semiconductor elements mounted on the wiring board with pins. It is a thing.

[0002]

2. Description of the Related Art Recently, as a wiring board with a pin used for mounting electronic parts such as semiconductor elements, for example, a plurality of insulating layers made of glass-epoxy board or insulating layers made of epoxy resin are laminated. A plurality of wiring conductors made of copper foil or the like are provided from the upper surface to the lower surface of the insulating substrate formed by, and a plurality of pin-bonding pads are formed at the portions of these wiring conductors led to the lower surface of the insulating substrate, and these pin-bonding pads are formed. A lead pin formed by providing a disk-shaped large-diameter portion having a thickness of about half the diameter of the shaft portion and a diameter of about 3 times the thickness at the upper end of the cylindrical shaft portion is abutted to the large-diameter portion and soldered. As a result, an organic material-based wiring board with pins, which is vertically installed, has been adopted. Such an organic-material-based wiring board with pins has the advantages that it is lighter in weight than the ceramic-material-based wiring board and that the electrical resistance of the wiring conductor is small. In such an organic material-based wiring board with pins, electronic components are mounted on the upper surface of the insulating substrate, and electrodes of the electronic components and wiring conductors are electrically connected via solder bumps or bonding wires. By sealing the electronic component with a lid member made of metal or ceramic or a sealing member made of potting resin, an electronic device as a product is obtained. In this electronic device, the lead pins on the lower surface of the insulating substrate are connected to the external electric circuit board. By connecting to the wiring conductor via a socket, solder, or the like, the electronic component mounted and mounted on the external electric circuit board is electrically connected to the external electric circuit.

As lead pins in such a wiring board, lead pins made of a copper alloy having a thermal expansion coefficient close to that of an insulating base made of resin have come to be used, and a lead pin and a pin pad are used. As the solder to be soldered, the stress from the external lead pins is soldered through the solder when external force is applied to the external lead pins in order to prevent the resin insulating base from being damaged by heat during soldering. In order to prevent the soldering pad from being peeled off due to a large voltage applied to the pad, for example, a lead-tin-antimony alloy or the like has a melting point of 270 ° C. or less and an elastic modulus of 50 GPa.
The following solders are being used.

[0004]

However, according to this conventional wiring board with a pin made of an organic material and an electronic device using the same, since the lead pin made of a copper alloy is soft and the rigidity of the large diameter portion is low, the lead pin is low. For example 30
When it is pulled vertically or obliquely with a force of about N, the large diameter portion is deformed by the force, and a large stress acts on the solder made of lead-tin-antimony alloy or the like that joins the lead pin and the pin attachment pad. , As a result, the solder with low yield stress breaks and the lead pins come off from the insulating substrate, and if the lead pins come off from the insulating substrate in this way, the electronic components to be mounted must be properly connected to the external electric circuit. It had a problem that it could not be done.

The present invention has been completed in view of the above conventional problems, and an object thereof is to prevent the lead pin from being removed even if the lead pin is pulled with a force of about 50 N, and to mount an electronic component mounted on an external electric circuit. An object of the present invention is to provide a highly reliable wiring board with a pin and an electronic device that can be normally connected to the wiring board.

[0006]

A wiring board with a pin according to the present invention is provided with a pinning pad electrically connected to the wiring conductor on the lower surface of an insulating substrate made of an organic material having a wiring conductor. In addition, a lead pin made of copper with a substantially circular truncated cone-shaped large-diameter portion formed on the upper end of the substantially cylindrical shaft portion is erected with solder interposed between the large-diameter portion and the pin attachment pad. If the diameter of the large diameter portion of the lead pin is A and the thickness of the large diameter portion is B, then 2.4 ≦
A / B ≦ 4.4 and the side surface of the large diameter portion of the lead pin has an angle of 20 to 45 ° with respect to the direction of the shaft portion.

Further, the electronic device of the present invention is characterized in that the electronic component is mounted on the pin-equipped wiring board having the above-mentioned structure, and the electrodes of the electronic component and the wiring conductors of the wiring board are electrically connected. It is a thing.

Since the wiring board with a pin and the electronic device using the same according to the present invention have the above-mentioned structure, even if a force for pulling the lead pin is applied, the stress caused by the force causes the diameter of the lead pin. It is possible to effectively prevent the solder from being largely concentrated and acting on the surface or a part of the inside of the solder through the large portion, and as a result, the lead pin can be firmly bonded to the insulating substrate.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing an example of an embodiment in which the present invention is applied to a wiring board with pins for mounting a semiconductor element and an electronic device mounting a semiconductor element on the wiring board. 2 is a wiring conductor, 3
Is a lead pin. The insulating substrate 1, the wiring conductor 2, and the lead pin 3 constitute the wiring substrate with pins of the present invention.
The electronic device of the present invention is formed by mounting the semiconductor element 4 as an electronic component on this.

The insulating substrate 1 is formed by impregnating a glass woven fabric in which glass fibers are woven vertically and horizontally with a thermosetting resin such as epoxy resin or bismaleimide triazine resin. It is an organic material-based multi-layered plate formed by laminating a plurality of insulating layers 1b each made of a thermosetting resin such as a bismaleimide triazine resin. The wiring conductor 2 is formed.

The core 1a constituting the insulating substrate 1 has a thickness
It has a diameter of about 0.3 to 1.5 mm and has a plurality of through holes 5 having a diameter of about 0.1 to 1.0 mm from its upper surface to its lower surface.
A part of the wiring conductor 2 is attached to the upper and lower surfaces and the inner wall of each through hole 5, and the upper and lower wiring conductors 2 are electrically connected through the through hole 5.

Such a core 1a is manufactured by heat-curing a sheet obtained by impregnating a glass fabric with an uncured thermosetting resin, and then drilling the sheet from the upper surface to the lower surface. The wiring conductors 2 on the upper and lower surfaces of the core body 1a
Has a thickness of 3 to 50 μm on the entire upper and lower surfaces of the core 1a sheet.
A certain amount of copper foil is attached and the copper foil is etched to form a predetermined pattern after curing. The wiring conductor 2 on the inner wall of the through hole 5 has a thickness of 3 to 50 μm formed by electroless plating and electrolytic plating on the inner wall of the through hole 5 after the through hole 5 is provided in the core body 1a.
It is formed by depositing a copper plating film of about m.

Further, the core 1a is filled with a resin column 6 made of a thermosetting resin such as an epoxy resin or a bismaleimide triazine resin inside the through hole 5. The resin column 6 is for closing the through hole 5 so that the insulating layer 1b can be formed immediately above and immediately below the through hole 5.
It is formed by filling an uncured paste-like thermosetting resin into the through holes 5 by a screen printing method, thermally curing the resin, and polishing the upper and lower surfaces thereof to be substantially flat. Then, the insulating layer 1 is formed on the upper and lower surfaces of the core 1a including the resin columns 6.
b are stacked.

Insulating layer 1b laminated on the upper and lower surfaces of the core 1a
Has a thickness of about 20 to 60 μm, and has a plurality of through holes 7 having a diameter of about 30 to 100 μm from the upper surface to the lower surface of each layer. These insulating layers 1b serve to provide an insulating space for wiring the wiring conductors 2 at high density. Then, by electrically connecting the upper layer wiring conductor 2 and the lower layer wiring conductor 2 through the through holes 7, it is possible to three-dimensionally form high-density wiring. For such an insulating layer 1b, an uncured thermosetting resin film having a thickness of about 20 to 60 μm is adhered to the upper and lower surfaces of the core body 1a, which is heat-cured and the through holes 7 are punched by laser processing. Further, it is formed by successively stacking the next insulating layer 1b thereon in the same manner. In addition, each insulating layer 1b
The wiring conductor 2 deposited on the surface and in the through holes 7 has a known copper plating film having a thickness of about 5 to 50 μm on the surface of each insulating layer 1b and in the through holes 7 each time each insulating layer 1b is formed. It is formed by applying a predetermined pattern by a pattern forming method such as a semi-additive method or a subtractive method.

The wiring conductor 2 formed from the upper surface to the lower surface of the insulating substrate 1 functions as a conductive path for connecting each electrode of the semiconductor element 4 to an external electric circuit board, and is provided on the upper surface of the insulating substrate 1. Part of the portion exposed on the lower surface of the insulating substrate 1 is an electronic component connection pad 2a joined to each electrode of the semiconductor element 4 via a solder bump 8 made of, for example, a lead-tin eutectic alloy. A pin attachment pad 2b for connecting the lead pin 3 as an external connection terminal is formed, and the lead pin 3 is formed on the pin attachment pad 2b via a solder 9 such as a lead-tin-antimony alloy having an elastic modulus of 50 GPa or less. It is erected. Such an electronic component connection pad 2a and a pin attachment pad 2b have an outer peripheral portion of a substantially circular pattern connected to the wiring conductor 2 as an outermost layer called a solder resist, as shown in FIG. By covering the outer peripheral edge by covering the insulating layer 1b with a width of about 15 to 150 μm, the diameter φ thereof is about 70 to 200 μm for the electronic component connection pad 2a, and substantially for the pin attachment pad 2b. It is formed to be about 0.5 to 2.5 mm. It should be noted that such a solder resist 1b effectively prevents an electrical short circuit between the electronic component connection pads 2a or the pin attachment pads 2b due to the solder 8 or 9 and also insulates the electronic component connection pad 2a and the pin attachment pad 2b. The bonding strength with respect to the substrate 1 is high.

Further, the lead pin 3 joined to the pin attachment pad 2b functions as an external connection terminal for connecting the mounted semiconductor element 4 to an external electric circuit.

In this wiring board, the electrodes of the semiconductor element 4 are bonded to the electronic component connection pads 2a through the solder bumps 8 to mount the semiconductor element 4, and the semiconductor element 4 is covered with a lid or a cover (not shown). An electronic device is formed by sealing with potting resin, and the electronic device of the present invention is mounted on the external electric circuit board by connecting the lead pin 3 in the electronic device to the wiring conductor of the external electric circuit board via a socket or solder. The Rukoto.

The lead pin 3 is, for example, 97.57% by weight of copper / 2.3% by weight of iron, as shown in the enlarged cross-sectional view of the main part in FIG.
/ A copper alloy containing 0.1% by weight of zinc / 0.03% by weight of phosphorus, with a diameter A of about 0.25 to 0.5 mm and a length of 1 to 3.5.
mm has a diameter B of 0.45 to the upper end of the substantially cylindrical shaft 3a.
It is formed by forming a substantially frustoconical large-diameter portion 3b called a nail head having a thickness C of about 0.25 mm and a thickness C of about 0.05 to 0.3 mm. Then, the large diameter portion 3b is bonded to the pin pad 2b through a solder containing 82% by weight of lead / 10% by weight of tin / 8% by weight of antimony and having an elastic modulus of 50 GPa or less. It is erected on 2b. As described above, according to the wiring board with a pin and the electronic device using the same of the present invention, since the lead pins 3 are made of a copper alloy, the thermal expansion coefficient of the insulating substrate 1 and the lead pins 3 is 15 pp.
It becomes close to about m / ° C., and it is possible to effectively prevent generation of a large stress due to a difference in thermal expansion coefficient between them. Also, the elastic modulus of the solder 9 is 50 G
Since it is Pa or less and is easily elastically deformed, when an external force is applied to the lead pin 3, the lead pin 3 is affected by the external force.
The stress generated between the pin 9 and the pad 2b can be well absorbed by the solder 9.

Further, in the present invention, the lead pin 3
Where A is the diameter of the large-diameter portion 3b and B is the thickness of the large-diameter portion 3b, 2.4 ≦ A / B ≦ 4.4 and the angle θ of the side surface of the large-diameter portion 3b with respect to the direction of the shaft portion 3a. Is 20 to 45 °. And that is important. Thus, the diameter of the large diameter portion 3b of the lead pin 3 is A, and the large diameter portion 3b is
Since the thickness B is 2.4 ≦ A / B ≦ 4.4, the ratio of the thickness to the diameter of the large diameter portion 3b is sufficiently large, so that the rigidity of the large diameter portion 3b is It will be expensive. Therefore, the lead pin 3 is, for example, 50
Even if it is pulled with a force of about N, it is possible to effectively prevent the large-diameter portion 3b from being deformed and exerting a large force on the solder 9.

Further, since the angle θ of the side surface of the large diameter portion 3b with respect to the direction of the shaft portion 3a is 20 to 45 °, when the pulling force is applied to the lead pin 3, the stress due to the pulling force is It can be dispersed almost uniformly on the surface and inside of the solder 9 through the side surface of the large portion 3b.
Even if the lead pin 3 is pulled with a force of about N, the solder 9
However, the lead pin 3 is not detached from the surface or inside thereof, and the mounted electronic component 4 can be normally connected to the external electric circuit.

The diameter A of the large diameter portion 3b of the lead pin 3
If the ratio A / B between the large diameter portion 3b and the thickness B of the large diameter portion 3b is less than 2.4, the thickness of the large diameter portion 3b becomes too large, and the wiring board with a pin and the electronic device of the present invention can be used as an external electric circuit board. When connecting, the large-diameter portion 3b becomes an obstacle and the weight balance of the lead pin 3 becomes poor, so that the workability at the time of soldering the lead pin 3 to the pin attaching pad 2b becomes poor, while the A / B is 4.4. When the lead pin 3 is pulled vertically or obliquely, the large-diameter portion 3b is deformed by the force and the top surface of the large-diameter portion 3b and the pinning pad 2b are exceeded. A large stress acts on the solder 9 existing between the lead 9 and the solder 9 existing between the top surface of the large diameter portion 3b and the pinning pad 2b even when the lead pin 3 is pulled by a force of about 30N, for example.
The solder 9 easily breaks from the inside of the. Therefore, the diameter A of the large diameter portion 3b of the lead pin 3 and the large diameter portion 3b
The ratio A / B with the thickness of is specified in the range of 2.4 ≦ A / B ≦ 4.4.

If the angle θ of the side surface of the large diameter portion 3b with respect to the direction of the shaft portion 3a is less than 20 °, when the lead pin 3 is pulled vertically or obliquely, the pulling force of the lead pin 3 is larger than that of the large diameter portion 3b. It acts on the surface of the solder 9 existing between the side surface of the large diameter portion 3b and the pin attaching pad 2b via the side surface in a largely concentrated manner, and for example, with a force of about 30 N, the lead pin 3
Even when pulling, the solder 9 easily breaks from the surface of the solder 9 existing between the side surface of the large-diameter portion 3b and the pinning pad 2b, and when θ exceeds 45 °,
When pulling the lead pin 3 vertically or diagonally,
The stress concentrates and acts on the inside of the solder 9 existing between the side surface of the large-diameter portion 3b and the pinning pad 2b via the side surface of the large-diameter portion 3b, and the lead pin 3 is pulled by a force of, for example, about 30N. Even in such a case, the solder 9 is easily broken from the inside of the solder 9 existing between the side surface of the large diameter portion 3b and the pin attachment pad 2b. Therefore, the angle θ of the side surface of the large diameter portion 3b with respect to the direction of the shaft portion 3a is specified in the range of 20 ° to 40 °.

Further, the diameter A of the large diameter portion 3b and the distance C from the exposed outer peripheral edge of the pin attachment pad 2b to the large diameter portion 3b.
If the ratio C / A with is less than 0.01, the pin attachment pad 2
Since the joint area between b and the solder 9 becomes small, it becomes difficult to firmly join the pin attachment pad 2b and the solder 9, and when a pulling force is applied to the lead pin 3, this force is generated. The stress that causes pin 2
When the C / A exceeds 0.5, the pinning pad 2b is likely to be peeled off from the insulating substrate 1 due to a large effect on the joint between the outer peripheral edge of b and the insulating substrate 1. Since a large amount of solder flows, a large amount of solder 9 is required to form a pool of a suitable size of solder 9 between the large diameter portion 3b and the pin attachment pad 2b. If the lead pin 3 and the pin attachment pad 2b are soldered together, a part of the solder 9 will flow over the large diameter portion 3b to the lower end portion of the lead pin 3, and the lead pin 3 will be connected to the external electrical circuit via a socket or solder. When electrically connecting to the wiring conductor of the substrate, the connection becomes difficult.
Therefore, the diameter A of the large diameter portion 3b and the pin attachment pad 2b
The ratio C / A with the distance C from the outer peripheral edge to the large diameter portion 3b is
The range of 0.01 ≦ C / A ≦ 0.5 is preferable.

The lead pin 3 is attached to the pin pad 2b.
In order to bond to the pin via the solder 9, a predetermined amount of solder paste for the solder 9 is applied to the pin attachment pad 2b by screen printing using a metal mask, and the large diameter portion 3b of the lead pin 3 is added to the top. A method is adopted in which the surfaces are abutted against each other, heated to melt the solder 9 and then cooled to room temperature.

[0025]

[Example] As a test substrate, two insulating layers of 40 μm in thickness made of epoxy resin were laminated on a core body of 0.8 mm in thickness made of glass fabric impregnated with epoxy resin, and on the uppermost insulating layer. , A pin-bonding pad with a diameter of 1.6 mm consisting of a copper-plated layer with a thickness of 15 μm is formed, and a solder resist layer with a thickness of 30 μm consisting of epoxy resin is formed on the pin-bonding pad with an opening with a diameter of 1.4 mm. Thus, a nickel plating layer having a thickness of 5 μm and a gold plating layer having a thickness of 0.03 μm were sequentially deposited on the surface of the pinning pad exposed from the opening of the solder resist layer.

As a lead pin for testing, copper 97.5
Made of a copper alloy containing 7% by weight / 2.3% by weight iron / 0.1% by weight zinc / 0.03% by weight phosphorus, with a shaft diameter of 0.46 mm
The shaft has a length of 3 mm, the diameter of the large diameter portion is 1.1 mm, the thickness of the large diameter portion is 0.25 to 0.45 mm, and the angle of the large diameter portion 3b with respect to the direction of the shaft portion 3a is in the range of 20 to 45 °. 10 different layers, each with a 2.5 μm thick nickel plating layer and a 0.03 μm thick gold plating layer sequentially deposited on the surface
Prepare one by one, and set the large diameter part of these test lead pins and the pin pad of the test board to 82% by weight lead / 10% by weight tin.
A sample for evaluation according to the present invention was obtained by soldering with a solder having an elastic modulus of 21 GPa and a volume of 0.11 mm ³ consisting of 8% by weight of antimony.

As a comparative example, 97.57% by weight of copper / iron
It consists of a copper alloy containing 2.3% by weight / 0.1% by weight zinc / 0.03% by weight phosphorus, the diameter of the shaft is 0.46 mm, the length of the shaft is 3 mm, and the diameter of the large diameter is 1.1 mm. The thickness of the large portion is 0.24 mm, the angle of the large diameter portion 3b with respect to the direction of the shaft portion 3a is 20 °, the thickness of the large diameter portion is 0.3 mm, and the large diameter portion 3
The angle of b is 10 ° with respect to the direction of the shaft 3a, and the thickness of the large diameter portion is 0.45 mm, and the angle of the large diameter portion 3b with respect to the direction of the shaft 3a is 50 °.
10 test lead pins each having a nickel plating layer and a gold plating layer with a thickness of 0.03 μm sequentially deposited are prepared, and the large diameter part of these test lead pins and the pin pad of the test board are used. 82 wt% lead / 10 wt% tin / 8 wt% antimony with an elastic modulus of 21 GPa and a volume of 0.11 mm
The evaluation sample for comparison was obtained by soldering with the solder of ³ .

Each of the evaluation samples thus obtained was fixed on a stage of a tensile tester at an angle of 20 °, and the shaft portion of the lead pin was chucked by a tensile jig, and then every minute.
The load at break was measured and evaluated by pulling at a speed of 15 mm. The results are shown in Table 1. In Table 1, sample numbers 1, 3, and 7 are comparative examples outside the scope of the present invention.

[0029]

[Table 1]

As shown in Table 1, in the evaluation samples according to the present invention (Sample Nos. 2, 4, 5, 6, and 8), a bonding strength of 50 to 63 N per pin was obtained for all the lead pins. In addition, the breakage occurred from the chucking position of the lead pin shaft, and was not broken from the solder. On the other hand, a comparative evaluation sample (Sample No. 1, 3 ,.
In 7), in all of the sample numbers, there were some that were broken from the solder with less than 50 N, and sufficient strength could not be obtained.

Thus, according to the wiring board with a pin of the present invention and the electronic device using the same, even if the lead pin 3 is pulled vertically or obliquely with a force of about 50 N, the lead pin 3 is not removed from the insulating substrate 1. It is possible to provide a wiring board with a pin and an electronic device capable of normally operating the mounted electronic components.

It is needless to say that the present invention is not limited to the above-described example of the embodiment, and various modifications can be made without departing from the scope of the present invention.

[0033]

According to the wiring board with a pin and the electronic device using the same of the present invention, when the diameter of the large diameter portion of the lead pin is A and the thickness of the large diameter portion is B, 2.4 ≦ A / B ≤4.4
In addition, since the side surface of the large diameter part of the lead pin has an angle of 20 to 45 ° with respect to the direction of the shaft part, the rigidity of the large diameter part is sufficiently high, and as a result, the force to pull it is applied to the lead pin. Even if it does, the large-diameter portion is not deformed by the force, and due to the inclination of the side surface of the large-diameter portion, the stress from the large-diameter portion is well dispersed on the surface and inside of the solder that joins the lead pin and the pin attachment pad. And as a result,
It is possible to provide a wiring board with a pin in which lead pins are firmly joined to an insulating substrate and an electronic component to be mounted can be normally connected to an external electric circuit.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an embodiment of a wiring board with pins and an electronic device according to the present invention.

FIG. 2 is an enlarged plan view of an essential part of an embodiment of a wiring board with pins and an electronic device according to the present invention.

FIG. 3 is an enlarged sectional view of an essential part of an embodiment of a wiring board with pins and an electronic device according to the present invention.

[Explanation of symbols]

1 ... Insulating base 2 ... Wiring conductor 2b ... Pin attaching pad 3 ... Lead pin 3a ... Shaft portion 3b ... Large diameter portion 4 ... ..Semiconductor element as electronic component 9 ... Solder A ... Diameter B of large diameter portion 3b ... Thickness θ of large diameter portion 3b ... Side surface of large diameter portion 3b Angle with respect to the shaft 3a direction

Claims (2)

[Claims] 1. A pin attachment pad electrically connected to the wiring conductor is provided on the lower surface of an insulating substrate made of an organic material having a wiring conductor, and the pin attachment pad is provided on the upper end of a substantially cylindrical shaft portion. A wiring board with a pin, wherein a lead pin made of a copper alloy having a truncated cone-shaped large-diameter portion is erected with solder interposed between the large-diameter portion and the pin attachment pad. A is the diameter of the portion and B is the thickness of the large diameter portion.
And 2.4 ≦ A / B ≦ 4.4, and the side surface of the large-diameter portion has an angle of 20 to 45 ° with respect to the direction of the shaft portion. . 2. An electronic device comprising an electronic component mounted on the wiring board according to claim 1, and an electrode of the electronic component electrically connected to the wiring conductor.