JPH06268340A - Wiring board - Google Patents

Abstract

PURPOSE:To protect a conductor part subjected to high current or high voltage and a soldered part against crack while reducing production cost. CONSTITUTION:In the printed board, a metal plate 13 having a predetermined pattern is fixed to a board 12 having a through hole 22 for passing the lead wire 19 of an electronic component. A hole 16 for passing the lead wire 19 and soldering is made through the metal plate 13 and the dimension of the insertion hole 22 is set larger than that of the connection hole 16. When the lead wire 19 is inserted into the connection hole 16 and soldered, upper and lower solder fillets 24, 25 are formed on the metal plate 13 around the connection hole 16 and thereby the strength and reliability are enhanced sufficiently at the soldered part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board suitable for a printed wiring board for mounting electronic parts through which a large current flows and electronic parts to which a high voltage is applied.

[0002]

2. Description of the Related Art A power supply circuit such as a microwave oven or an electromagnetic cooker is provided on a printed wiring board, and such a printed wiring board is equipped with electronic components through which a large current flows and electronic components to which a high voltage is applied. Has been done. In this printed wiring board, if there is a crack in the conductor pattern through which a large current flows or the conductor pattern to which a high voltage is applied, there is a risk that sparks may occur and burn out. In addition, the lead wire derived from the electronic component in which a large current flows and the electronic component in which a high voltage is applied is connected to the conductor pattern by soldering, but even if there is a crack in this soldered part There was a risk that sparks would be generated there and burned.

As a measure to prevent the above-mentioned soldered portion from cracking, conventionally, a method of increasing the strength of the soldered portion by performing soldering using a hamper and a double-sided board are used. There is a method of increasing the strength of a soldered portion by forming a through hole and performing soldering.

[0004]

In the case of the above conventional configuration,
Although it is possible to prevent cracks from entering the soldered portion by soldering through the eyelets or through holes, there is no need to worry about cracks in the conductor pattern or disconnection of the conductor pattern. It is not an effective measure.
In addition, the configuration in which the soldering is performed using the through holes has a drawback that the manufacturing cost is considerably high.

Therefore, an object of the present invention is to reliably prevent the occurrence of cracks in the conductor portion through which a large current flows, the conductor portion to which a high voltage is applied, and the soldering portion, and to reduce the manufacturing cost. In providing the substrate.

[0006]

A wiring board according to the present invention includes a board for mounting electronic components, a metal plate attached to the board and having a predetermined pattern shape, and the electronic board formed on the board. It has an insertion hole for inserting the lead wire derived from the component, and a connection hole formed in the metal plate for inserting the lead wire for soldering connection, and further, a hole diameter of the insertion hole. The feature is that the size is made larger than the hole diameter size of the connection hole.

In this case, when the metal plate is attached to the substrate, it is preferable that the jumper wire be penetrated through the metal plate and the substrate and caulked to be attached. Further, it is preferable that the metal plate is bonded to the substrate via the high melting point solder.

[0008]

According to the above-mentioned means, unlike the printed conductor pattern, a metal plate that hardly cracks is formed in a predetermined pattern shape and attached to the substrate. Alternatively, if a current with a large voltage value is applied, sparks will not occur and there is no risk of burnout. Then, the hole diameter dimension of the insertion hole of the substrate is
Since it is larger than the hole diameter of the connection hole of the metal plate, when the lead wire of the electronic component is inserted into the connection hole of the metal plate and soldered, the fillet of solder is sufficiently formed on both sides of the metal plate. Therefore, the strength and reliability of the soldered portion are increased. In this case, since the diameters of the holes formed in the metal plate and the substrate are simply adjusted, the manufacturing cost is lower than that in the case where the through holes are formed.

On the other hand, when mounting the metal plate on the substrate,
If the jumper wire is penetrated through the metal plate and the substrate and caulked, the mounting strength of the metal plate is increased and the cost for mounting is also reduced. Further, when the metal plate is bonded to the substrate via the high melting point solder, the metal plate is not peeled off from the substrate even when the substrate is poured into the solder bath for automatic soldering.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to a printed wiring board of an electromagnetic cooker will be described below with reference to FIGS. First, referring to FIG. 4 showing the electrical configuration of the electromagnetic cooker, the inverter circuit 2 for supplying a high frequency current to the induction heating coil 1 includes a rectifier 3, a choke coil 4, a smoothing capacitor 5, a resonance capacitor 6, a switching element 7 and a damper. It is composed of a diode 8 and the like. The switching element 7 is composed of, for example, an IGBT, and the driver circuit 10 is controlled by, for example, a microcomputer 9 which is a control means for controlling the heating operation.
On / off control is performed via. Each electronic component that constitutes the inverter circuit 2 is mounted on a printed wiring board 11 (indicated by a chain double-dashed line in FIG. 4) which is a wiring board.

As shown in FIG. 1, the printed wiring board 11 is composed of, for example, a phenol resin substrate 12 and a copper metal plate 13 attached to the lower surface of the substrate 12 in FIG. As shown in FIG. 2, the metal plate 13 is composed of a plurality of metal plates 13 formed to have various pattern shapes as needed.

Now, a mounting structure for mounting the metal plate 13 on the substrate 12 will be described. First, on the metal plate 13,
As shown in FIG. 2, three types of holes 14, 15 and 16 are formed in advance. In this case, the holes 14 are a pair of through holes for inserting both ends of the U-shaped jumper wire 17,
The hole 15 is a through hole through which the temporary fixing clip 18 is inserted, and the hole 16 is a connection hole through which a lead wire 19 derived from an electronic component (for example, the capacitor 6) is inserted and soldered.

On the other hand, the through hole 14,
Holes corresponding to the through hole 15 and the connection hole 16 are formed in advance. In this case, as shown in FIG.
Corresponding to the hole 20, the through hole 15 corresponding to the hole 21,
Holes 22 are formed corresponding to the connection holes 16. Here, FIG.
2, the hole 22 is an insertion hole 22 for inserting the lead wire 19 of the electronic component, and the hole diameter dimension A of the insertion hole 22 is set to be larger than the hole diameter dimension B of the connection hole 16. Has been done. The diameter B of the connection hole 16
Is set to be slightly larger than the outer diameter dimension C of the lead wire 19.

When the metal plate 13 is attached to the substrate 12, first, the metal plate 13 is aligned to a predetermined position on the lower surface of the substrate 12 in FIG. 1, and then the temporary fixing clip 18 is attached to the hole 21 of the substrate 12 and the metal. It is inserted into the through hole 15 of the plate 13. As a result, the metal plate 13 is temporarily fixed to the substrate 12. Subsequently, in this temporarily fixed state, both ends of the U-shaped jumper wire 17 are inserted into the pair of holes 20 and 20 of the substrate 12 and the pair of through holes 14 and 14 of the metal plate 13, and then the jumper wire 17 is inserted. Bend the tips of both ends with a pin etc. and crimp. As a result, the metal plate 13 is attached and fixed to the substrate 12. The work of inserting the jumper wire 17 and caulking it is automatically performed by using a so-called jumper wire self-inserting machine.

After that, the lead wire 19 of the electronic component is inserted into the connection hole 16 of the metal plate 13 and soldered. in this case,
The solder resist 23 (see FIG. 3) is applied in advance to the portion of the lower surface of the metal plate 13 to which solder should not adhere. Then, as shown in FIG.
After being placed on the electronic component, the lead wire 19 of the electronic component is inserted into the insertion hole 22 of the substrate 12 and the connection hole 16 of the metal plate 13, and then the substrate 12 is poured into a solder bath for automatic soldering to be soldered. Automatically.

By this soldering, an upper solder fillet 24 and a lower solder fillet 25 are formed around the connection hole 16 into which the lead wire 19 is inserted, as shown in FIG. This is because the hole diameter dimension A of the insertion hole 22 is larger than the hole diameter dimension B of the connection hole 16, so that the solder reaches the upper surface side from the lower surface side of the metal plate 13 through the connection hole 16 and adheres thereto. The upper solder fillet 24 and the lower solder fillet 25 sufficiently enhance the strength and reliability of the soldered portion and prevent the soldered portion from being cracked.

Although not shown, a conductor pattern (that is, copper foil) having a predetermined shape is formed on the lower surface of the substrate 12 by printing (method such as etching), and the conductor pattern is relatively small. A current having a current value and a voltage value flows. Specifically, in the electric circuit of FIG. 4, the switching element 7 is composed of, for example, an NPN-type transistor, and the connection line connecting the base of the transistor 7 and the driver circuit 10 has a magnitude of current and voltage. Since a small control signal flows, the above-mentioned printed conductor pattern is used.

According to this embodiment having such a structure, unlike the conventional printed conductor pattern of the conventional structure, the metal plate 13 which is hardly cracked is formed in a predetermined pattern shape, and is formed on the substrate 12. Since it is configured to be attached,
Even if a large current is applied to the metal plate 13 or a large voltage is applied to it, no spark is generated and there is no possibility of burning.

Since the hole diameter A of the insertion hole 22 of the substrate 12 is made larger than the hole diameter B of the connection hole 16 of the metal plate 13, the lead wire 19 of the electronic component is inserted into the connection hole 16 of the metal plate 13. When the soldering is performed, the fillets 24 and 25 of the solder are sufficiently formed on the upper and lower surfaces of the metal plate 13, and the strength and reliability of the soldered portion are increased. In this case, since the diameters of the holes 16 and 22 formed in the metal plate 13 and the substrate 12 are simply adjusted, the manufacturing cost can be reduced as compared with the case where the through holes are formed. Further, since only the holes 16 and 22 are formed, it is easier to deal with the lead wires 19 having different outer diameter dimensions and shapes, as compared with the case of using the eyelets.

Further, when the metal plate 13 is attached to the substrate 12, the jumper wire 17 is penetrated through the metal plate 13 and the substrate 12 and caulked, so that the attachment strength of the metal plate 13 to the substrate 12 is increased and The cost for mounting is also reduced. This prevents the metal plate 13 from peeling off from the substrate 12 when the substrate 12 is poured into the solder bath when performing automatic soldering.

FIGS. 5 to 8 show a second embodiment of the present invention, and the second embodiment is applied to a printed wiring board of a microwave oven. First, in FIG. 8 showing the electrical configuration of the microwave oven, a magnetron drive circuit 32 for driving the magnetron 31 includes a rectifier 33, a smoothing circuit 34, an inverter circuit section 35, and a step-up transformer 3.
6 and a voltage doubler rectifier circuit 37. In this case, the smoothing circuit 34 includes a choke coil 38, a smoothing capacitor 39, a resistor 40 and the like, and the inverter circuit portion 35 includes a resonance capacitor 41, a switching element 42, a damper diode 43, a varistor 44, a resistor 45 and the like. The voltage doubler rectifier circuit 37 is a high voltage rectifier 46, 4
6 and a high voltage condenser 47. A noise prevention capacitor 48 and a varistor 49 are connected between the input terminals of the rectifier 33.

In the present embodiment, the switching element 42 of the inverter circuit section 35 is composed of, for example, an IGBT and is configured to be on / off controlled by a control circuit 50 for controlling the heating operation. This control circuit 50 is a microcomputer. It is configured to include. Each electronic component forming the magnetron drive circuit 32 and the control circuit 50 is a wiring board, for example, a printed wiring board 51.
(Shown by a chain double-dashed line in FIG. 8). Further, in FIG. 8, a large amount of current flows through a connection line having a solid underline or an overline among the connection lines connecting the electronic components, and a connection line having a wavy underline or an overline. A high voltage is applied to the connection line, and a connection line with a dashed underline or an overline is a connection line that is dangerous if it is disconnected.

Now, the printed wiring board 51 will be described in detail with reference to FIGS. FIG. 5 shows FIG.
FIG. 6 is a vertical sectional view showing a specific structure of a portion X indicated by a two-dot chain line in the electric circuit of FIG. 6, and FIG. 6 is a bottom view of the portion. First, as shown in FIG.
Is a substrate 52 made of an insulating resin, and a conductor pattern 5 printed on the lower surface of the substrate 52 in FIG. 5 with an adhesive 53.
4 and a metal plate, for example, a copper plate 56, which is adhered to the lower surface of the conductor pattern 54 with the high melting point solder 54.

Here, the conductor pattern 54 is made of, for example, a copper foil, and is adhered to the lower surface of the substrate 52 with an adhesive agent 53. Briefly describing the case where the conductor pattern 54 is formed by printing, a copper foil having substantially the same size as the substrate 52 is adhered to the substrate 52, and then an etching process is performed to obtain a predetermined pattern shape (see FIG. 6). The copper foil is left and the conductor pattern 54 is formed. Then, an insertion hole 57 for mounting an electronic component is formed in the substrate 52 and the conductor pattern 54 so as to correspond to the land portion 54a of the conductor pattern 54. Of the insertion holes 57, the hole through which the lead wire 58 of the resistor 40 (a component to which a large current does not flow or a high voltage is applied) is inserted has a hole diameter dimension slightly larger than the outer diameter dimension of the lead wire 58. Is set to. Further, the hole diameter of the hole through which the lead wire 58 of the choke coil 38 and the smoothing capacitor 39 is inserted (see also FIG. 7) is set to be considerably larger than the outer diameter dimension of the lead wire 58.

Thereafter, the copper plate 56 (see FIG. 6) previously formed in a predetermined pattern shape is replaced with the conductor pattern 5 described above.
The high melting point solder 55 is bonded to the bonding portion of No. 4 above.
In this case, before bonding, the land portion 56a of the copper plate 56
First, a connection hole 59 for inserting and connecting the lead wire 58 derived from the electronic component is formed. In this case, the diameter B of the connection hole 59 (see also FIG. 7) is determined by the lead wire 58.
It is set to be slightly larger than the outer diameter dimension of. Thereby, the hole diameter dimension A of the insertion hole 57 corresponding to the connection hole 59 is configured to be larger than the hole diameter dimension B of the connection hole 59. In the printed wiring board 51, the copper plate 56 having such a configuration is a connection line having a solid line underline or overline in the electric circuit shown in FIG. 8 or a connection line having a wavy line underline or overline. It is used for parts corresponding to connecting lines with lines, broken underlines or overlines, respectively.

Before soldering, the solder resist 60 is applied in advance to the portions of the lower surface of the copper plate 56 and the conductor pattern 54 where the solder should not adhere. After that, when the electronic components are soldered and mounted on the printed wiring board 51 having the above configuration, the electronic components are mounted on the substrate 52.
The lead wire 58 of each electronic component is placed on the connection hole 59 of the copper plate 56 and the insertion hole 57 of the conductor pattern 54.
Then, the board 52 is poured into a solder bath for automatic soldering to perform soldering. By this soldering, soldered portions are formed around the connection hole 59 of the copper plate 56 into which the lead wire 58 is inserted and around the insertion hole 57 of the conductor pattern 54, as shown in FIG. At the time of this soldering, since the copper plate 56 is adhered by the high melting point solder 55, the copper plate 56 is not peeled off from the substrate 52 and the conductor pattern 54.

Here, the copper plate 56 in which the lead wire 58 is inserted
An upper solder fillet 61 and a lower solder fillet 62 are formed around the connection hole 59, as shown in FIG. This is because the hole diameter dimension A of the insertion hole 57 is the connection hole 5
This is because the diameter is larger than the hole diameter dimension B of 9 and the solder reaches the upper surface side from the lower surface side of the copper plate 56 through the connection hole 59 and adheres thereto. Therefore, the upper solder fillet 61 and the lower solder fillet 62 sufficiently increase the strength and reliability of the soldered portion, and reliably prevent cracks from forming in the soldered portion. As a result, the second
Also in this embodiment, it is possible to obtain substantially the same operational effects as in the first embodiment.

[0028]

As is apparent from the above description, the present invention attaches a metal plate having a predetermined pattern shape to a substrate, and forms an insertion hole for inserting a lead wire of an electronic component in the substrate, Then, the lead wire is inserted into the metal plate to form a connection hole for soldering, and the hole diameter of the insertion hole is made larger than the hole diameter of the connection hole. It is possible to surely prevent cracks from being generated in the conductor portion and the soldered portion to which a high voltage is applied and to reduce the manufacturing cost.

[Brief description of drawings]

FIG. 1 is a side view of a board on which an electronic component according to a first embodiment of the present invention is mounted.

FIG. 2 is a bottom view showing a substrate and a metal plate.

FIG. 3 is an enlarged vertical side view of a soldered portion.

[Fig. 4] Electric circuit diagram

FIG. 5 is a partial vertical cross-sectional side view of a board on which an electronic component according to a second embodiment of the present invention is mounted.

FIG. 6 is a partial bottom view of the substrate.

FIG. 7 is an enlarged vertical side view of a soldered portion.

FIG. 8 is an electric circuit diagram.

[Explanation of symbols]

3 is a rectifier, 4 is a choke coil, 5 is a smoothing capacitor, 6 is a resonance capacitor, 7 is a switching element, 8 is a damper diode, 11 is a printed wiring board (wiring board), 12 is a board, 13 is a metal plate, and 16 is Connection hole, 17
Is a jumper wire, 18 is a temporary clip, 19 is a lead wire, 22 is an insertion hole, 24 is an upper solder fillet, 25 is a lower solder fillet, 33 is a rectifier, 34 is a smoothing circuit,
35 is an inverter circuit section, 36 is a step-up transformer, 37 is a voltage doubler rectifier circuit, 38 is a choke coil, 39 is a smoothing capacitor, 40 is a resistor, 41 is a resonance capacitor, 42 is a switching element, 43 is a damper diode, and 44 is a varistor. , 45 is a resistor, 46 is a high voltage rectifier, 47 is a high voltage capacitor, 48 is a noise preventing capacitor, 49 is a varistor, 51 is a printed wiring board (wiring board), 52 is a substrate, 53 is an adhesive, 54 is a conductor pattern, 55 Is a high melting point solder, 56 is a copper plate (metal plate), 57 is an insertion hole, 58 is a lead wire, 59 is a connection hole, 60 is a solder resist, and 61 is a solder resist.
Indicates an upper solder fillet, and 62 indicates a lower solder fillet.

Claims (3)

[Claims] 1. A substrate for mounting an electronic component, a metal plate attached to the substrate and having a predetermined pattern shape, and an insertion member for inserting a lead wire formed on the substrate and led out from the electronic component. A wiring board comprising a hole and a connection hole formed in the metal plate for inserting the lead wire for soldering connection, and the hole diameter dimension of the insertion hole is larger than the hole diameter dimension of the connection hole. . 2. The wiring board according to claim 1, wherein the metal plate is attached to the board by piercing a jumper wire and caulking the board. 3. The wiring board according to claim 1, wherein the metal plate is adhered to the board through a high melting point solder.