JP3346215B2 - Printed wiring board and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board and a method of manufacturing the same, and more particularly to a structure for improving the strength of soldering between an insulating substrate and a heat slag.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 11, a mounting through hole 97 for mounting an electronic component 98 on an insulating substrate 99 is provided as a printed wiring board, and conductor patterns 93 and 91 are provided on the upper and lower surfaces thereof. There are things. Conductor pattern 9
3 is an electronic component 98 by a bonding wire 982.
Is electrically connected to

A heat slug 96 is adhered to the lower surface of the insulating substrate 99 by a conductive adhesive 95 containing silver as a main component. The upper surface of the heat slug 96 has a through hole 9 for mounting.
7, the bottom of which has an adhesive 98 such as solder.
9, an electronic component 98 is adhered and fixed.

The conductor pattern 93 and the conductor pattern 91 provided on the upper and lower surfaces of the insulating substrate 99 are electrically connected by an annular circuit 971 provided on the inner wall of the mounting through hole 97. The current flowing through the conductor pattern 91 is transmitted to the heat slug 96 via the conductive adhesive 95 and is grounded from the heat slug 96.

[0005]

However, in the above-mentioned conventional printed wiring board, since the conductive adhesive 95 is mainly composed of silver, the cost is high. In addition, since the bonding area is limited, the resistance value of the conductive bonding material 95 varies greatly. Furthermore, since the heat slug 96 is bonded to the metal surface of the conductor pattern 91 using the adhesive 95, there is a problem that the bonding strength is low.

Conventionally, in manufacturing the printed wiring board, as shown in FIG. 12, a mounting through hole 97 is formed in an insulating substrate 99, and then a copper foil is formed on the front and back surfaces of the insulating substrate 99. Conductive patterns 93 and 91 are formed by sticking, etching and plating. Further, an annular circuit 971 is formed on the inner wall of the mounting through hole 97 by plating. Next, the heat slug 96 is arranged on the lower surface of the insulating substrate 99 via the adhesive 95. At this time, the heat slug 96 is arranged so as to cover the mounting through-hole 97 of the insulating substrate 99.

Next, as shown in FIG.
The side surfaces 999 of the heat slug 96 and the side surface 999 of the heat slug 96 are brought into contact with the positioning guide 960 to position the insulating substrate 99 and the heat slug 96, and then the adhesive 95 is cured and bonded.

However, the thickness of the heat slag 96 is 0.1
If the thickness is very thin (~ 1.0 mm), heat slag 96
It is difficult to bring the side surface 969 into contact with the positioning guide 960, and positioning may not be performed. When bonding the heat slug 96 and the insulating substrate 99 with the adhesive 95, the adhesive 95 protrudes from between the two, and the protruding adhesive 95 is used as the positioning guide 960.
The positioning operation may be complicated.

Therefore, as shown in FIG.
It is conceivable that a protruding piece 961 extending from the side surface of the heat slug 96 is inserted into the inside of the heat slug 30 and solder 911 is filled in the conduction hole 930 to join and fix the protruding piece 961. . The heat slug 96 and the insulating substrate 99 are bonded with an insulating resin adhesive 969. The surface of the insulating substrate 99 is covered with a solder resist film 98. The inner wall of the conduction hole 930 is covered with a metal plating film 931.

However, a material made of Ni plating is easily oxidized, and the soldering strength is reduced unless rust prevention treatment is performed. Even in Ni plating, the heat slag 96 made of a plating material containing a small amount of phosphorus (P) and the solder 911 are not well adapted to each other, and the soldering strength of the protruding piece 961 is low. Therefore, there is a problem that the adhesive strength between the heat slug 96 and the insulating substrate 99 becomes insufficient.

Therefore, it is conceivable to improve the adhesion to the insulating substrate 99 by adding a trace amount of boron (B) to the Ni plating to prevent rust from occurring. However, in this case, the plating process on the heat sink is costly, and the printed wiring board becomes expensive.

The present invention has been made in view of the above-mentioned conventional problems, and the positioning operation between the heat slug and the insulating substrate is easy, and
An object of the present invention is to provide a printed wiring board having excellent adhesive strength between an insulating substrate and a heat slag and a method for manufacturing the same.

[0013]

According to a first aspect of the present invention, there is provided a printed wiring board having an insulating substrate provided with a conductor pattern and a conduction hole, and a heat slug provided on a surface of the insulating substrate.
The heat slag has a protruding piece which is extended from the side face and is bent. The protruding piece and the side face of the heat slag are covered with a gold plating film or a palladium plating film, and The opposing surface of the slag facing the insulating substrate and the opposite surface opposite to the opposing surface are covered with a nickel plating film for preventing solder contamination. are joined by soldering are inserted into the interior of the conducting holes, and the solder is inside smell of the introducing holes
Not only fix the protruding piece, but also
Form a fillet between the side of the heat slag and
A printed wiring board, wherein the conduction hole and a side surface of the heat slag are joined .

The operation and effect of the present invention will be described. In the printed wiring board of the present invention, the protruding piece is a portion which is inserted into the inside of the conduction hole and is joined and fixed by solder. The surface of the projecting piece is covered with a gold plating film or a palladium plating film. A gold plating film or a palladium plating film has excellent solder wettability. Therefore, the solder is sufficiently wet on the surface of the protruding piece, and excellent solder joint strength is obtained.

The opposite surface of the heat slag facing the insulating substrate and the opposite surface opposite to the opposite surface are portions that are not desired to be contaminated by solder. The reason is that when solder adheres to the opposing surface of the insulating substrate, cleaning becomes difficult and the flux cannot be removed in some cases. This is because the adhesive layer may be defective due to the penetration of the solder. If the solder is applied to the opposite surface of the insulating substrate, the solder is completely applied, and when the heat slug is mounted or comes into contact with the housing, the heat slug or the housing and the opposite surface of the insulating substrate are completely removed. This is because it is difficult to adhere to the surface, and there is a problem that heat dissipation is poor. The facing surface and the opposite surface of the heat slag are covered with a nickel plating film having low solder wettability. Therefore, the solder does not diffuse more than necessary into the heat slag, and the contamination of the facing surface and the opposite surface by the solder can be prevented.

The projecting piece is a portion integrally extended from the side surface of the heat slag. This protruding piece is inserted into the inside of the conduction hole and is joined by soldering. for that reason,
The bonding area of the heat slag increases, and excellent bonding strength between the heat slag and the insulating substrate can be obtained. In addition, the reliability of the electrical connection between the heat slag and the conduction hole is improved, the resistance value can be suppressed low, and the variation is small. Further, the projecting pieces serve as escape paths for heat generated from the electronic components, and the heat dissipation effect is improved.

Further, by inserting the protruding piece into the conduction hole, the positioning between the heat slug and the insulating substrate can be accurately performed. Therefore, a positioning guide is not required, and positioning of the heat slug can be easily performed. Further, when the heat slag and the insulating substrate are temporarily bonded to each other with an adhesive such as an adhesive sheet, there is no problem that the melted adhesive adheres to the positioning guide. Therefore, the quality and productivity of the printed wiring board are improved,
The manufacturing process can be simplified and the cost can be reduced.

Next, the upper Symbol solder, not only for fixing the projecting piece inside of the introducing hole, to form a fillet between the side surface of the conducting hole and the heat slug, the electrically The through hole is connected to the side of the heat slag.
You. Thereby, the joint area between the heat slag and the solder increases, and the joint strength of the heat slag further improves.

Further, as in the invention of claim 2, the protruding piece is preferably provided an even number on the side surface of the heat slug. Thereby, the positioning operation of the heat slug is further facilitated, and the connection reliability of the heat slug is further improved.

Next, as in the third aspect of the present invention, it is preferable that the projecting pieces are arranged symmetrically with respect to the center of the heat slag. Thereby, the connection reliability of the heat slug can be obtained in a well-balanced manner.

Next, as in the invention of claim 4 , it is preferable that the protruding piece is arranged at a position farthest from a center position of the heat slag. Thereby, the overall connection reliability of the heat slag can be ensured.

According to a fifth aspect of the present invention, the length of the insertion portion of the projecting piece inserted into the conductive hole is
Preferably, the depth is 50 to 100% of the depth of the conduction hole. As a result, the projecting piece is securely locked to the wall surface of the conduction hole, and the positioning of the heat slug can be easily performed. Also, the bonding area between the protruding piece and the solder is increased, and the bonding strength of the heat slag is further improved.

On the other hand, if the length of the projecting piece inserted into the hole for conduction is shorter than 50% of the depth of the hole for conduction, the joining strength of the heat slag may be reduced.
If the tip of the protruding piece protrudes from the hole for conduction,
The tip of the protruding piece may obstruct the surface mounting of the printed wiring board.

According to a sixth aspect of the present invention, the insulating substrate has a mounting through hole for mounting an electronic component, and the mounting through hole is formed by the facing surface of the heat slag. Preferably it is coated. As a result, the electronic components are directly mounted on the surface of the heat slag. Therefore, heat generated during the operation of the electronic component can be efficiently transmitted to the heat slag, and the heat radiation characteristics are improved.

The thickness of the protruding piece is 0.1 to 0.5.
It is preferably 5 mm. As a result, the strength of the protruding piece can be kept high, and the connection reliability of the heat slug to the insulating substrate is further increased. Also, bending of the protruding piece is easy. In addition, it can be inserted into a small-diameter conduction hole, and high-density mounting of the conduction hole can be realized. When the thickness of the heat slag is larger than the thickness of the protruding piece, the above-mentioned thickness can be obtained by cutting the portion to be the protruding portion in advance by pressing or etching to make it thinner, and then performing bending. .

The thickness of the heat slag is 0.1
It is preferably about 1.0 mm. As a result, it is possible to reduce the thickness of the printed wiring board while maintaining sufficient heat dissipation. On the other hand, the thickness of heat slag is 0.1
If it is less than mm, the strength of the heat slag may be reduced. If it exceeds 1.0 mm, the printed wiring board becomes thick and heavy.

Next, as a method of manufacturing the printed wiring board, for example, a conductive pattern and a conduction hole whose inner wall is covered with a metal plating film are formed on an insulating substrate. Forming, projecting a metal plate to form a heat slag and forming a protruding piece extending from a side surface of the heat slag; and a facing surface of the heat slag facing at least the insulating substrate; Prevents solder contamination on the opposite side opposite to the opposite side
Forming a nickel plating film to, substantially vertical and step, the projecting piece on the opposite surface side of the heat slug to form a gold plating layer or palladium plating film on the side surfaces of the protruding pieces and the heat slug And arranging the facing surface of the heat slag toward the insulating substrate, bonding the facing surface and the insulating substrate with an adhesive layer, and placing the projecting piece inside the conduction hole. The step of inserting and supplying solder to the inside of the conduction hole and heating it to melt the solder and solder-join the inner wall of the conduction hole and the protruding piece, and the solder is
Fillet between the hole for conduction and the side of the heat slag.
A hole is formed between the hole for conduction and the side of the heat slag.
And a bonding step.

Thus, the soldering strength between the heat slag and the metal plating film covering the inner wall of the conduction hole is increased. Therefore, the quality reliability and heat dissipation of the printed wiring board are improved. Further, by inserting the protruding piece into the inside of the conduction hole, the positioning between the heat slug and the insulating substrate can be performed, so that a positioning guide is not required. Further, the positioning of the heat slag can be performed accurately and easily. Furthermore, when the heat slag and the conduction hole are temporarily bonded with an adhesive, there is no problem that the adhesive adheres to the positioning guide.

In supplying the solder into the conduction hole, it is preferable to use a method of dropping solder balls into the conduction hole. Since the volume of the solder ball is controlled to a constant value, the supply of solder into the conduction hole can be constant. Further, the size of the conduction hole can be accurately controlled by a drilling device or the like. Therefore, the contact area between the conduction hole and the heat slag can be made constant, and variation in the resistance value between the two can be suppressed.

The conductive hole can be formed by, for example, irradiating a laser beam, or drilling with a drill or a router. In supplying the solder into the conduction hole, it is preferable to use a method of printing a solder paste or a method of supplying a ball-shaped solder inside or above the conduction hole. Thus, the solder can be easily supplied into the conduction hole.

The material of the metal plate for forming the heat slag is copper (Cu), aluminum (Al), nickel (N
i) It is preferably a metal material or alloy mainly composed of iron (Fe). As the insulating substrate, a resin single substrate, a resin substrate containing a filler, or the like can be used. As the resin, for example, an epoxy resin, a polyimide resin, a bismaleimide triazine resin, or the like can be used. As the filler, for example, glass fiber, glass cloth, or the like can be used.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 Regarding a printed wiring board according to an embodiment of the present invention,
This will be described with reference to FIGS. Printed wiring board 1 of this example
1, has an insulating substrate 5 provided with conductor patterns 33, 31 and conduction holes 30, and a heat slug 2 provided on the surface of the insulating substrate 5. As shown in FIG.

As shown in FIGS. 1 to 3, heat slag 2
Has a protruding piece 21 extending from the side surface 29 and bent. As shown in FIG. 2, the projecting piece 21 and the side surface 29 of the heat slag 2 are covered with the gold plating film 11. A facing surface 25 of the heat slag 2 facing the insulating substrate 5 and a facing surface 26 opposite to the facing surface 25 are covered with the nickel plating film 13.

As shown in FIG. 3, the projecting piece 21 is inserted into the conduction hole 30 and joined and fixed by the solder 4. Solder 4 is provided with projecting piece 21 inside conduction hole 30.
In addition to joining the heat slag 2
A fillet 41 is formed between the hole 30 and the side surface 29 of the heat slug 2.

As shown in FIG. 4, four projecting pieces 21 are provided at corners 290 of the side surface 29 of the heat slug 2. The protruding piece 21 is arranged at a position farthest from the center position C of the heat slug 2. These projecting pieces 2
1 is arranged symmetrically with respect to the center C of the heat slug 2. As shown in FIG. 3, the length L1 of the insertion portion 210 of the protruding piece 21 inserted into the conduction hole 30 is shown.
Is substantially the same as the depth H of the conduction hole 30.

The upper surface of the insulating substrate 5 is, as shown in FIG.
A mounting through hole 51 for mounting the electronic component 8, a conductor pattern 33 provided around the mounting portion 51, and a conduction hole 3;
And a land 302 provided around the periphery of the center. The conductor pattern 33 is provided with a bonding pad 331 for making electrical conduction with the electronic component 8 via the bonding wire 81.
And a pad 330 for joining a solder ball for electrical conduction with a mating member.

As shown in FIG. 7, the lower surface of the insulating substrate 5 has a wide conductor pattern 31 provided around the mounting through hole 51 and a land 303 provided around the conduction hole 30.
And The conductor pattern 31 is electrically connected to the land 303.

As shown in FIG. 8, the heat slug 2 is joined to the lower surface of the insulating substrate 5 with the protruding piece 21 inserted into the conduction hole 30. As shown in FIG.
The mounting through hole 51 is covered with the facing surface 25 of the heat slag 2. As shown in FIG.
On the upper surface of the mounting through hole 51 for mounting,
The electronic component 8 is fixed by an adhesive 85 such as a silver paste. The heat slug 2 is used as a grounding circuit. The upper and lower surfaces of the insulating substrate 5 are covered with a solder resist film 7.

Next, a method for manufacturing the printed wiring board of this embodiment will be described. First, an insulating substrate is prepared by impregnating a glass cloth with a thermosetting resin (for example, an epoxy resin). The thickness of the insulating substrate is 0.2 mm. Next, as shown in FIG. 1, a through hole 51 for mounting and a hole 30 for conduction are formed in the insulating substrate 5 by using a drilling device such as a drill.
Drilling.

Next, as shown in FIGS. 3, 6, and 7,
Conducting holes 3 by a usual method such as plating, exposure, etching, etc.
In addition to applying a metal plating film 301 to the inner wall of
The conductor pattern 33 and the conduction hole 3
A land 302 of 0 is formed (FIG. 6). Further, on the lower surface of the insulating substrate 5, a conductor pattern 31 is formed so as to surround the mounting hole 51, and a land 303 of the conduction hole 30 is formed (FIG. 7). The diameter of the conduction hole 30 is 1.0 mm. Next, as shown in FIG. 1, the upper and lower surfaces of the insulating substrate 5 are covered with a solder resist film 7. At this time, the pads 330 of the conductor pattern 33 and the periphery of the conduction hole 30 and the mounting through hole 51 are exposed.

Also, a thickness of 0.25 mm made of oxygen-free copper
Prepare a metal plate and perform external processing with a mold. As a result, as shown in FIG. 5, a heat slug 2 is obtained in which the protruding piece 21 is extended from the corner 290 of a square having a side of 25 mm. The length L2 of the protruding piece 21 is 0.6 mm.

Then, as shown in FIGS. 1 to 3, the entire surface of the heat slag 2 was electroplated to a thickness of 5 μm.
Is coated with a nickel plating film 13. Next, the flat portion of the heat slag 2, that is, the facing surface 25 facing the insulating substrate 5
A general electroplating method is applied to the heat slag 2 while the opposite surface 26 on the opposite side is masked. As a result, only the protruding piece 21 and the side surface 29 of the heat slag 2
It is covered with a gold plating film 11 having a thickness of 0.3 μm.

Next, as shown in FIG. 5, the projecting piece 21 is bent at a position separated by the length L1 of the insertion portion 210 of the projecting piece 21 using a mold. The length L1 of the insertion section 210 is 0.2 mm. Either the plating step or the bending step may be performed first.

Next, as shown in FIGS. 1 and 8, the heat slug 2 is disposed on the upper surface of the insulating substrate 5 with the adhesive 6 interposed in a state where the opposing surface 25 of the heat slug 2 faces. At this time, the projecting piece 21 of the heat slug 2 is inserted into the conduction hole 30. Thereby, the heat slug 2 is positioned with respect to the insulating substrate 5. As the adhesive 6, a prepreg obtained by impregnating a glass cloth with a thermosetting resin (for example, epoxy resin) is used. Next, the adhesive 6 is thermally cured to bond the heat slag 2 to the insulating substrate 5.

Next, the ball-shaped solder 4 is supplied onto the conduction hole 30 on the side of the insulating substrate 5 where the heat slag 2 is not bonded, and the solder 4 is heated and melted. As a result, the inside of the conduction hole 30 is filled with the solder 4 and
A fillet 41 is formed between the conduction hole 30 and the projecting piece 21. At this time, the portion of the heat slug 2 to which the solder 4 adheres is near the projecting piece 21 and the projecting piece 21 on the side surface 29 of the heat slug 2 as shown in FIG. In addition, when the solder 4 is supplied to the inside of the conduction hole 30, as shown in FIG. 6, a ball-shaped solder is also supplied to the pad 330, and bonding is performed by heating and melting.

Thereafter, as shown in FIG. 6, the electronic component 8 is mounted inside the mounting through hole 51, and the electronic component 8 and the conductor pattern 33 are connected by the bonding wire 81. Thus, the printed wiring board 1 is obtained.

Next, the operation and effect of this embodiment will be described.
In the printed wiring board of this example, as shown in FIG.
The protruding piece 21 is a part which is inserted into the inside of the conduction hole 30 and is joined and fixed by the solder 4. The surface of the projecting piece 21 is covered with the gold plating film 11. The gold plating film 11 has excellent solder wettability. Therefore, the projecting piece 2
The solder 4 is sufficiently wetted on the surface of the substrate 1 to obtain excellent solder joint strength.

The opposing surface 25 of the heat slug 2 facing the insulating substrate 5 and the opposing surface 26 opposite to the opposing surface 25 are portions that are not desired to be contaminated by the solder 4.
It is covered with a nickel plating film 13 having low solder wettability. Therefore, the solder 4
Is not diffused, and contamination of the opposed surface 25 and the opposite surface 26 by the solder 4 can be prevented.

The projecting piece 21 is a part integrally extended from the side surface 29 of the heat slug 2. The protruding piece 21 is inserted into the conduction hole 30 and is joined by soldering. Therefore, the bonding area of the heat slag 2 increases, and excellent bonding strength between the heat slag 2 and the insulating substrate 5 can be obtained. Further, the heat slag 2 and the conduction hole 30
The reliability of the electrical connection with the device is also improved. Further, the projecting piece 21
Is an escape route for heat generated from the electronic component 8, and the heat radiation effect is improved.

Further, by inserting the projecting piece 21 into the inside of the conduction hole 30, the positioning of the heat slug 2 and the insulating substrate 5 can be performed accurately. Therefore, a positioning guide is not required, and positioning of the heat slug can be easily performed. When the heat slag and the insulating substrate are temporarily bonded by an adhesive such as an adhesive sheet,
There is no problem that the molten adhesive adheres to the positioning guide. Therefore, the quality and productivity of the printed wiring board 1 are improved, and the simplification of the manufacturing process and the reduction in cost can be realized.

Embodiment 2 As shown in FIG. 9, the printed wiring board of this embodiment
The length L1 of the insertion portion 210 into the conduction hole 30 at 1 is 50% of the depth H of the conduction hole 30. In this case as well, excellent joint strength can be obtained between the projecting piece 21 and the conduction hole 30 as in the above embodiment.
Other configurations are the same as those of the first embodiment. In this embodiment, the same effects as those of the embodiment can be obtained.

Embodiment 3 In the printed wiring board 1 of this embodiment, as shown in FIG.
Is provided. Heat slag 2 is 25mm long and 30mm wide
It is a rectangle with a size of mm. Others are the first embodiment.
Is the same as Also in this example, the same effect as in the first embodiment can be obtained.

Fourth Embodiment The present embodiment is different from the first embodiment in that a palladium plating film is formed on the projecting pieces and side surfaces of the heat slag instead of the gold plating film. The thickness of the palladium plating film is 0.3 μm. The palladium plating film is formed by a general electroplating method. Other configurations are the same as those of the first embodiment. Also in this example, the same effect as in the first embodiment can be obtained.

[0054]

According to the present invention, there is provided a printed wiring board in which the positioning operation between the heat slag and the insulating substrate is easy and the adhesive strength between the insulating substrate and the heat slag is excellent, and a method for manufacturing the same. can do.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a printed wiring board according to a first embodiment, taken along line AA of FIG. 8;

FIG. 2 is a partial perspective view of a heat slag in the first embodiment.

FIG. 3 is a cross-sectional view of the printed wiring board for illustrating a bonding state of the projecting pieces according to the first embodiment.

FIG. 4 is a perspective view of a heat slug according to the first embodiment.

FIG. 5 is a plan view of a heat slug showing a bent portion in the first embodiment.

FIG. 6 is a back view of the printed wiring board according to the first embodiment.

FIG. 7 is a plan view of an insulating substrate according to the first embodiment.

FIG. 8 is an explanatory diagram showing an arrangement relationship between an insulating substrate and a heat slag in the first embodiment.

FIG. 9 is a partial cross-sectional view of a printed wiring board for illustrating a bonding state of protruding pieces according to the second embodiment.

FIG. 10 is an explanatory diagram showing an arrangement relationship between an insulating substrate and a heat slag in a third embodiment.

FIG. 11 is a sectional view of a printed wiring board in a conventional example.

FIG. 12 is an exploded explanatory view of a printed wiring board in a conventional example.

FIG. 13 is an explanatory view showing a method of positioning a heat slug and an insulating substrate in a conventional example.

FIG. 14 is a cross-sectional view of another conventional printed wiring board.

[Explanation of symbols]

 1. . . Printed wiring board, 11. . . 12. Gold plated film, . . 1. Nickel plating film, . . Heat slag, 21. . . Projecting piece, 210. . . Insertion part, 30. . . Conduction holes, 31, 33. . . 3. conductor pattern; . . Solder, 41. . . Fillets, 5. . . Insulating substrate, 51. . . 5. Through hole for mounting, . . Adhesive, 7. . . Solder resist film,

Continuation of the front page (56) References JP-A-7-78927 (JP, A) JP-A-7-307569 (JP, A) JP-A-9-55594 (JP, A) JP-A 48-63244 (JP) , U) Fully open sho 59-3596 (JP, U) Fully open sho 57-119545 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05K 1/02 H05K 1/05 H05K 1/18 H05K 3/46 H05K 7/12 H05K 7/20 H01L 23/12 H01L 23/35

Claims (7)

(57) [Claims] An insulation provided with a conductor pattern and a conduction hole.
A substrate and a heat slug provided on the surface of the insulating substrate.
In a printed wiring board, the heat slag extends from the side and is bent.
And the side surfaces of the projecting piece and the heat slag are provided with a gold plating film or
Is covered with a palladium plating film and
Opposed to the insulating substrate in the heat slag
Surface, and the opposite surface opposite the opposite surface,Prevents solder contamination
in order toThe heat slag is covered with a nickel plating film.
And then joined by solderYes, In addition, the solder is provided inside the conduction hole with the protrusion.
In addition to fixing the pieces,
A fillet is formed between the side of the slag and
Joins the hole and the side of the heat slag Features
And printed wiring board. Wherein Oite to claim 1, said protruding piece is a printed circuit board, characterized in that provided an even number on the side surface of the heat slug. 3. The printed wiring board according to claim 2, wherein the protruding pieces are arranged symmetrically with respect to the center of the heat slug. 4. A any one of claims 1 to 3
The printed wiring board, wherein the projecting piece is arranged at a position farthest from a center position of the heat slug. 5. A any one of claims 1-4,
A printed wiring board, wherein a length of an insertion portion of the protruding piece inserted into the inside of the through hole is 50 to 100% of a depth of the through hole. 6. In any one of claims 1 to 5 ,
A printed wiring board, wherein the insulating substrate is provided with a mounting through hole for mounting an electronic component, and the mounting through hole is covered with the facing surface of the heat slag. 7. A step of forming a conductor pattern and a conduction hole having an inner wall covered with a metal plating film on an insulating substrate, punching a metal plate to form a heat slag, and forming a heat slag from a side surface of the heat slag. forming a protruding piece that extends, in the heat slug, surface facing at least the insulating substrate, and solder to the opposite surface opposite to the facing surface
A step of forming a nickel plating film for preventing contamination ; a step of forming a gold plating film or a palladium plating film on the side surfaces of the projecting pieces and the heat slag; and placing the projecting pieces on the side facing the heat slag. Bending in a substantially vertical direction, arranging the facing surface of the heat slag toward the insulating substrate, bonding the facing surface and the insulating substrate with an adhesive layer, and connecting the projecting piece to the conduction hole. By supplying solder into the conduction hole and heating it,
The solder is melted to join the inner wall of the conduction hole and the protruding piece by solder , and the solder is connected to the conduction hole and the heat sink.
Form a fillet between the side of
Joining the conduction hole and the side surface of the heat slag to the printed wiring board.