JP2002299770A - Circuit board and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board which can be reduced in size. SOLUTION: The circuit board includes an insulation sheet 29 and a lead frame 30 stacked on the sheet 29; the lead frame 30 has a plurality of electrically conductive patterns 28a and 28b; and the underlying sheet 29 are extended, up to the upper surfaces of the conductive patterns 28a and 28b between the patterns 28a and 28b, and covers both sides of the upper surfaces of the conductive patterns 28a and 28b positioned on both sides thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a circuit board and a method for manufacturing the same.

[0002]

2. Description of the Related Art There is a circuit board using a lead frame as a circuit board through which a large current flows.

That is, in the conventional device having a printed pattern formed on a substrate, a large current cannot be applied to the printed pattern. Therefore, a large current can be applied by using a thick lead frame. It is.

Specifically, a circuit board using the above-described lead frame is formed by stacking a lead frame on a sheet,
By pressing, the two are integrated.

In this case, a plurality of conductive patterns are provided on the lead frame, and when the above-mentioned heating and pressing are performed, a part of the lower sheet protrudes between the conductive patterns up to the upper surface of the conductive patterns. The insulation between the conductive patterns is maintained.

[0006]

What is problematic in the above conventional example is the insulation distance between the conductive patterns.

That is, a high-voltage conductive pattern and a low-voltage conductive pattern are confused on a lead frame, and a large insulation distance is required between adjacent high-voltage and low-voltage conductive patterns. Will be lost.

Accordingly, an object of the present invention is to reduce the size of a circuit board.

[0009]

Means for Solving the Problems In order to achieve the object, the invention according to claim 1 of the present invention comprises an insulating sheet and a lead frame superposed on the sheet, wherein the lead frame comprises: Having a plurality of conductive patterns, between the conductive patterns, the lower sheet protrudes above the upper surface of the conductive patterns, on the upper surface of at least one conductive pattern of the conductive patterns located on both sides thereof,
This is a configuration in which the side facing the other conductive pattern is covered.

With such a configuration, a lower insulating sheet protrudes above the upper surface between adjacent conductive patterns, and on the upper surface of at least one of the conductive patterns located on both sides thereof. , Because it covers the side facing the other conductive pattern, the effective insulation distance between adjacent conductive patterns is increased, which not only prevents short-circuiting between these adjacent conductive patterns, Accordingly, the distance between adjacent conductive patterns can be shortened, and the size can be reduced.

Next, according to a second aspect of the present invention, the lead frame is separated into a high voltage side and a low voltage side, and the distance between the high voltage side conductive pattern and the low voltage side conductive pattern adjacent to each other across the separation portion is determined. The circuit board according to claim 1, wherein the insulation distance between the high-voltage side and the low-voltage side in the lead frame is longer than between the adjacent high-voltage-side conductive patterns, and between the low-voltage-side adjacent conductive patterns. This is preferable as an insulation measure.

A third aspect of the present invention is the circuit board according to the second aspect, wherein a concave portion is formed in a sheet in a separation portion between a high voltage side and a low voltage side of the lead frame. Since the concave portion is formed in the sheet in the separation section on the side, the creepage distance between the high-pressure side and the low-pressure side becomes longer, which is preferable as an insulation measure.

Next, according to a fourth aspect of the present invention, an insulating sheet is superimposed on one of the front and back surfaces of the lead frame, and a plate body is superimposed on the other, and then the three polymers are heated and pressurized. In the method of manufacturing a circuit board for peeling a plate body from a lead frame, a portion of the plate body facing the lead frame on a surface of the lead frame facing the space between the conductive patterns constituting the lead frame faces the plate body side from the lead frame. A method of manufacturing a circuit board in which a concave portion is formed, and the concave portion is extended to at least one side of the plate body of the conductive pattern located on both sides of the concave portion, wherein the sheet, the lead frame, and the polymer of the plate body are heated. By applying pressure while pressing, the sheet is fluidized and penetrates into the concave portion of the plate from between the conductive patterns constituting the lead frame.

In this case, since the concave portion of the plate extends to at least one plate surface of the conductive pattern located on both sides of the concave portion, the molten material of the sheet penetrates into the concave portion and the plate of the conductive pattern is formed. It will cover part of the side.

As a result, a part of the sheet exists between the adjacent conductive patterns, and a part of the sheet not only protrudes to the plate body side to be peeled later, but also a part of at least one of the conductive patterns. As a result, the effective insulation distance between adjacent conductive patterns is increased, and as a result, a short circuit between adjacent conductive patterns can be prevented.

By forming a concave portion in the plate, a part of the sheet can be protruded toward the plate between the conductive patterns, and a part of the side of the plate of the conductive pattern can be covered. You can also.

According to a fifth aspect of the present invention, there is provided the circuit board manufacturing method according to the fourth aspect, wherein the plate body has flexibility, and the plate body has close contact with the lead frame. This prevents the sheet from flowing out to the conductive pattern outside the recess.

That is, since electronic components and the like are mounted on the conductive pattern, if even the portion is covered with the outflow portion of the sheet, it becomes impossible to mount the electronic components.
Alternatively, extra work such as a step of removing the sheet outflow portion is required, and these are prevented.

Next, a sixth aspect of the present invention is the method for manufacturing a circuit board according to the fifth aspect, wherein the plate is formed of a resin, and a heat conductor is mixed into the resin. Since the heat transfer member is mixed in the sheet, heat can be easily transmitted from the plate body side to the lead frame and the sheet, and as a result, the sheet can be fluidized smoothly.

According to a seventh aspect of the present invention, there is provided the method of manufacturing a circuit board according to the fourth aspect, wherein the plate is formed of a metal plate, and heat is easily transmitted from the plate to the lead frame and the sheet. As a result, the sheet can be smoothly fluidized.

Next, according to the invention of claim 8, the lead frame has a structure in which a high voltage side and a low voltage side are separated by a dummy pattern,
The method according to claim 4, wherein the dummy pattern is removed from the sheet after the lead frame is integrated on the sheet, and the dummy pattern is formed after the sheet and the lead frame are integrated. By removing, the high voltage side and the low voltage side of the lead frame are separated on the sheet, so that a sufficient insulation measure can be taken between them.

According to a ninth aspect of the present invention, there is provided the circuit board manufacturing method according to the eighth aspect of the present invention, wherein the dummy pattern is formed as an uncovered portion of the protruding portion of the sheet. Since the dummy pattern is not covered by the dummy pattern, the dummy pattern can be easily peeled off from the sheet.

According to a tenth aspect of the present invention, a plurality of conductive patterns are provided on the high voltage side and the low voltage side of the lead frame, respectively. 9. The method of claim 8, wherein the lead frame having the first distance formed thereon is integrated on the sheet, the sheet between each adjacent first distance pattern is raised to the upper surface of the conductive pattern, and then the dummy pattern is removed. In this method, the insulation distance between the high voltage side and the low voltage side of the lead pattern can be easily ensured by removing the dummy pattern.

When the lead frame and the sheet are integrated, a part of the sheet protrudes upward between adjacent patterns. At this time, the distance between the patterns is reduced by the first pattern due to the presence of the dummy pattern. , The amount of the sheet softening during heating and pressurization of the polymer of the sheet and the lead frame and the amount of protrusion between the patterns become substantially the same between the patterns.

For this reason, there is no variation in the insulation distance between adjacent patterns due to the fact that the patterns are pushed in the horizontal direction due to the difference in the amount of the sheet protruding between the patterns.

Next, according to an eleventh aspect of the present invention, the lower surfaces of the low-voltage side and high-voltage side conductive patterns of the lead frame are roughened,
11. The method for manufacturing a circuit board according to claim 9, wherein the lower surface side of the dummy pattern is a non-rough surface, and the lower surface side of each of the conductive patterns on the low voltage side and the high voltage side is roughened to form a lower surface. The bonding force with the sheet is increased, and the conductive pattern is stably arranged.

Since the lower surface of the dummy pattern is non-rough, it can be easily removed even after the lead frame and the sheet are integrated.

According to a twelfth aspect of the present invention, there is provided the method of manufacturing a circuit board according to the fourth aspect of the present invention, wherein the inner surface of the concave portion of the plate is a mirror surface. Part of the sheet flowing out of the recess does not firmly adhere to the inner surface of the concave portion, so that the subsequent peeling operation of the plate can be smoothly performed.

A thirteenth aspect of the present invention is the method for manufacturing a circuit board according to the fourth or twelfth aspect, wherein a release agent is applied to the inner surface of the concave portion of the plate. Is applied, a part of the sheet flowing out from between the conductive patterns does not firmly adhere to the inner surface of the concave portion, so that the subsequent peeling operation of the plate body can be smoothly performed.

According to a fourteenth aspect of the present invention, there is provided the method for manufacturing a circuit board according to any one of the fourth to thirteenth aspects, wherein a ventilation hole is formed in the recess of the plate. Since the air holes are formed, when a part of the sheet flows between the conductive patterns toward the concave portion, the air existing in that portion is discharged from the air holes, and as a result, The flow of a part of the sheet can be performed smoothly.

According to a fifteenth aspect of the present invention, the bottom surface of the concave portion of the plate is formed in a dome shape protruding on the side opposite to the lead frame, and a vent hole is formed in the center of the dome.
Wherein the concave portion of the plate body is formed in a dome shape, and a vent hole is formed in the center of the concave portion, whereby a part of the sheet smoothly enters the concave portion of the plate body. Will be done.

[0032]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes an automobile, and the automobile 1 comprises a main body 2 and four tires 3 supporting the main body 2. The tire 3 is driven by an engine 4 and a drive motor 5. That is, at the time of starting, the engine is started by the drive motor 5 and is driven by the engine 4 when a predetermined speed is reached.

In order to drive the drive motor 5, a very large voltage is required. In this embodiment, a DC power supply 6 of 300V is provided. The drive motor 5 is driven by the DC power supply 6. The DC power supply 6 is DC /
The DC power is converted to 14 V by the DC converter 7, thereby charging the DC power supply 8 to 14 V.

The DC power supply 8 drives another load, for example, the light 9. FIG. 2 shows only the electric circuit portion having the above configuration.

As shown in FIG. 2, the DC power supply 6 is connected to the drive motor 5 and the DC / DC converter 7. The generator 10 is driven by the engine 4, and the voltage obtained by the generator 10 charges the DC power supply 6.

This 300 V DC power supply 6 is a DC / DC
It is connected to a converter 7 and charges the DC power supply 8 to 14 V on the secondary side.

FIG. 3 shows a connection portion between the DC / DC converter 7 and the light 9.

That is, when a current I ₀ flows from the DC / DC converter 7 to the light 9 via the DC power supply 8, a voltage drop necessarily occurs in the line resistance 11.

As a result, the DC power supply 8 may not be charged to 14V, and the light 9 may not be supplied with 14V. Thus, when the current I ₀ flows to the light 9 as described above, the voltage of the DC power supply 8 and the voltage of the voltage supplied to the load are reduced by increasing the voltage of the DC / DC converter 7. Need to be prevented.

Therefore, in the present embodiment, the DC / DC converter 7 is configured as shown in FIG.

The DC / DC converter 7 has a transformer 14 between an input terminal 12 and an output terminal 13.
The open / close control means 16 is connected to the primary winding 14 a of the transformer 14 via the switching means 15.

A smoothing circuit including a diode 17 and a capacitor 18 is connected to the secondary winding 14b of the transformer 14. The output terminal 13 has resistors 19, 2
0 is connected in series, and the connection point is connected to the negative input terminal of the operational amplifier 21.

The positive input of the operational amplifier 21 has a reference power supply 2
2 is connected, and the output of the operational amplifier 21 is connected to the opening / closing control means 16.

A current detecting means 23 composed of a resistor is connected between the secondary winding 14b and the output terminal 13. This current detecting means 23 is formed by a small resistor. However, a voltage is generated by the current flowing even with this small resistance, the voltage is amplified by the amplifier 24, and this voltage is input to the negative input terminal of the operational amplifier 25. A reference power supply 26 is connected to a positive input terminal of the operational amplifier 25.

The output of the operational amplifier 25 is connected via a resistor 27 to a connection point between the resistors 19 and 20.

In the above configuration, as shown in FIG. 3, the light 9 is connected to the DC power
There when driven, in Fig. 4, so that the large current flows in the I _0. When this large current flows, it is detected by the current detecting means 23, amplified by the amplifier 24, and input to the negative input of the operational amplifier 25.

Then, the operational amplifier 25 uses the reference voltage 2
6 and a current corresponding to the result of the comparison is caused to flow through the resistor 27. The current flowing through this resistor 27 is
The larger the current I ₀ , that is, the current flowing through the light 9, the larger the current flowing through the resistor 27.

When the load current I ₀ increases, the voltage of the current detecting means 23 increases, and the voltage is amplified by the amplifier 24 and supplied to the negative input of the operational amplifier 25.

When the difference between the negative input of the operational amplifier 25 and the reference voltage decreases, the output voltage of the operational amplifier 25 decreases. As a result, the voltage at the connection point between the resistors 19 and 20 also decreases, and as the voltage decreases, the voltage at the negative input of the operational amplifier 21 also decreases. When the negative input of the operational amplifier 21 decreases, the output voltage of the operational amplifier 21 increases. When the output voltage of the operational amplifier 21 rises, one of the transformers 14
The configuration is such that the current of the photodiode provided to separate the secondary side from the secondary side becomes small.

When the current flowing through the photodiode decreases, the on-time of the switching means 15 in the PWM control circuit provided in the opening / closing control means 16 increases, thereby generating a secondary winding 14b of the transformer 14. Voltage increases.

As a result, the voltage between both ends of the DC power supply 8 in FIG. 3 is increased, and the voltage drop caused by driving the light 9 can be compensated.

In other words, even in this case, the light 9
Can be operated stably.

The DC / DC converter 7 shown in FIG. 4 is constructed by mounting the various electronic components shown in FIG. 4 on the circuit board 28 shown in FIG.

The right side of the circuit board 28 shown in FIG. 5 is the high voltage side 28A, that is, the area where various electronic components on the primary winding 14a side of the transformer 14 in FIG. 4 are mounted, and the left side is the low voltage side. Side 28B, ie the transformer 1 of FIG.
4 is an area where various electronic components on the secondary winding 14b side are mounted.

The circuit board 28 is formed by superposing a lead frame 30 on a sheet 29 and applying pressure while heating. The above-mentioned various electronic components are provided with respective conductive patterns on the high voltage side 28A and the low voltage side 28B. 28
a, 28b and are in an electrically conductive state.

The outer peripheral frame 30a of the lead frame 30 shown in FIG. 5 is cut off before or after mounting the various electronic components.

As shown in FIG. 6, when the sheet 29 and the lead frame 30 are superposed and integrated, the sheet 29 between the adjacent conductive patterns 28a and between the adjacent conductive patterns 28b extends up to the upper surface of the conductive patterns 28a and 28b. It is solidified after being raised (this point will be described later in detail with reference to FIGS. 9 and 10).

Therefore, between adjacent conductive patterns 28a,
28b, the outer peripheral frame 3 of the lead frame 30
No shift to the left or right occurs after the separation of 0a.

The high pressure side 28A and the low pressure side 28B
The distance between the adjacent conductive patterns 28a and 28b is substantially the same as the first distance Ta as shown in FIGS. On the other hand, the conductive pattern 28a on the lowest voltage side 28B among the conductive patterns 28a on the high voltage side 28A and the highest voltage side 28b on the conductive pattern 28b on the low voltage side 28B.
The distance between the A conductive patterns 28b is the first distance Ta.
The second distance Tb is larger than the second distance Tb.

That is, as shown in FIG. 5, the high voltage side 28A and the low voltage side 28B are separated into left and right sides, and the second distance Tb provided therebetween is divided into a plurality of conductive patterns 28a provided on the high voltage side 28A and the low voltage side 28B, respectively. , 28b the first distance T
If it is larger than a, the insulation distance between the high voltage side 28A and the low voltage side 28B on the circuit board 28 can be sufficiently set, and sufficient insulation measures can be taken.

By separating the high pressure side 28A and the low pressure side 28B, the separated high pressure side 28A and low pressure side 28B are separated.
Of the adjacent conductive patterns 28a, 2
It is only necessary to separate the high-voltage side 28A and the low-pressure side 28B from each other by a first distance Ta smaller than the second distance Tb, so that the size of the circuit board 28 can be reduced as a whole.

The high pressure side 28A having the second distance Tb
As shown in FIG. 6, a concave portion 31 is formed in the raised portion of the sheet between the conductive patterns 28a and 28b on the low voltage side 28B and the low voltage side 28B. Patterns 28a, 28
Since the creepage distance between b becomes longer, sufficient insulation measures can be taken.

Hereinafter, a method of manufacturing the circuit board 28 shown in FIGS. 5 and 6 will be described.

First, the sheet 29 is formed on the release film 32 as shown in FIG. The forming method is to prepare a mixture slurry comprising at least an inorganic filler, a thermosetting resin composition and a solvent, and form the mixture on the release film 32 by film formation. As a method of forming a film, an existing doctor blade method, a coater method, and an extrusion molding method can be used. Then, a flexible sheet 29 can be obtained by drying only the solvent of the formed slurry.

Similarly, a slurry of a mixture of at least an inorganic filler, a thermosetting resin solid at room temperature, a thermosetting resin composition liquid at room temperature and a solvent is prepared, and a film is formed on the release film 32 in the same manner as described above. Then, the flexible sheet 29 can be obtained by drying the solvent.

Examples of the thermosetting resin include an epoxy resin, a phenol resin and a cyanate resin. Further, as the inorganic filler, Al ₂
O ₃ , MgO, BN and AlN can be mentioned. Examples of the solvent include ethyl carbitol, butyl carbitol, and butyl carbitol acetate.

Examples of the thermosetting resin which is liquid at room temperature include epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, and liquid phenol resin.

Further, examples of the solvent include methyl ethyl ketone, isopropanol and toluene. If necessary, a coupling agent, a dispersant, a colorant, and a release agent can be further added to the composition of the sheet 29.

Further, as described above, by adding a solvent or adding a thermosetting resin which is liquid at room temperature, and drying the solvent, a semi-cured or partially cured state having an appropriate viscosity (102 to 105 Pa · s) is obtained. Is obtained. In addition, 10
If the viscosity is lower than 2 Pa · s, not only is the sheet-like material too sticky to be peeled off from the release film 32,
Workability is poor because the amount of deformation after processing is large. Also, 10
If the viscosity is higher than 5 Pa · s, there is no flexibility and processing at room temperature becomes difficult. Desirably, the viscosity is in the range of 103 to 104 Pa · s in terms of workability and workability.

When the sheet 29 is cured, a large amount of the inorganic filler is filled, so that the thermal expansion coefficient can be made almost the same as that of the lead frame 30 made of a copper plate, and the sheet 29 has excellent heat dissipation. Become.

FIGS. 8 to 10 are views showing the steps of manufacturing a circuit board 28 manufactured using the sheet 29. FIGS. FIG.
As shown in FIG.
The lead frame 30 and the sheet 29 are polymerized and integrated by primary molding at 120 ° C.

The lead frame 30 can be obtained by punching a copper plate into a desired shape with a metal mold, or can be formed by an etching method.

As described above, the lead frame 30 has the conductive pattern 28a on the high voltage side 28A, the conductive pattern 28b on the low voltage side 28B, and the dummy pattern 30b therebetween, and the peripheral portions of these patterns 28a, 28b, 30b. Is connected to the outer peripheral portion 30a. The processed surface of the lead frame 30 is treated by nickel plating or solder plating to prevent oxidation of copper.

The back surface of the lead frame 30 on which the sheets 29 of the conductive patterns 28a and 28b are integrated is made to have a higher surface roughness by sandblasting or the like in order to further increase the bonding strength. The back side of the dummy pattern 30b, which is easy to be attracted but is finally unnecessary, is fixed with a heat-resistant tape or is in a non-roughened state so as to be easily peeled later.

FIG. 10 shows that the plate 33 is overlaid on the back side of the lead frame 30 on the front side of the sheet 29 in the range of 50 to 120.degree.
The sheet 29 is pressurized while being heated at a temperature of 4 ° C. to fluidize a part of the sheet 29, between the conductive patterns 28a and 28b, between the conductive pattern 28a and the dummy pattern 30b,
8 shows a state in which the thermosetting resin is cured after the space between 8b and the dummy pattern 30b is raised. The lead frame 30
Has a structure in which the high-pressure side 28A and the low-pressure side 28B are separated by a dummy pattern 30b as shown in FIG. 8, and after the lead frame 30 is integrated on the sheet 29, the plate 33 is peeled upward as shown in FIG. Then, the dummy pattern 30b is separated from the outer peripheral frame 30a, and then the dummy pattern 30b is removed from the sheet 29.

As described above, if the dummy pattern 30b is removed after the sheet 29 and the lead frame 30 are integrated, the high-pressure side 28A and the low-pressure side 28B of the lead frame 30 are placed on the sheet 29 as shown in FIGS. Recess 31
, Sufficient insulation measures can be taken during this time.

When the lead frame 30 and the sheet 29 are integrated, a part of the sheet 29 flows and protrudes upward between adjacent patterns. At this time, the presence of the dummy pattern 30b causes As can be understood from FIG. 6, the distance between the patterns is the first distance T
a is substantially the same.

For this reason, the seat 29 and the lead frame 3
When the polymer 29 is heated and pressurized, the amount of the sheet 29 softened and fluidized and raised between the patterns becomes substantially the same between the patterns.

As a result, the sheet 2 protruding between the respective patterns
9 does not cause a variation in the insulation distance between adjacent patterns due to the fact that the patterns are pushed in the horizontal direction due to a difference in the amount of the part 9.

Before the integration with the sheet 29, a resist film is provided on the upper surfaces of the conductive patterns 28a and 28b by a mask to form the mounting positions of the various electronic components and the electrical connection positions. In the state of FIG. 5 completed,
Various electronic components are mounted.

Further, the outer peripheral portion 30a of the lead frame 30
After projecting out of the circuit board 28,
This is bent upward, for example, and used as a connection terminal to another circuit board.

Further, a heat radiating plate may be provided on the lower surface of the sheet 29 to further enhance the heat radiation.

Next, another feature of this embodiment will be described.

In this embodiment, as shown in FIGS. 6 and 9, between the conductive patterns 28a and 28b, and between them and the dummy pattern 30b, the sheet 29 below the conductive pattern 28a, 28b and the dummy pattern 30b Project above the upper surface of the. The conductive patterns 28a and 28b located on both sides are covered only on both sides on the upper surface.

Thus, between adjacent conductive patterns 28a and 28b, conductive pattern 28
a, 28b, which protrude above the upper surfaces of the conductive patterns 28a, 28b, and cover both sides of the upper surfaces of the conductive patterns 28a, 28b, the effective insulation distance between the adjacent conductive patterns 28a, 28b becomes longer, and as a result, these adjacent conductive patterns Short circuit between 28a and 28b can be prevented.

In order to achieve the above, the plate 33
FIG. 10 shows a conductive pattern 2 forming the lead frame 30 on the lower surface facing the lead frame 30 as shown in FIG.
8a and 28b, and between the dummy frame 30b and the lead frame 30,
A concave portion 33a is formed upward toward the side. The recesses 33a are formed on the conductive patterns 28a,
It extends to both sides of 28b.

For this reason, the sheet 29, the lead frame 3
0, by pressurizing the polymer of the plate body 33 while heating as described above, a part of the sheet 29 is fluidized, and between the conductive patterns 28a and 28b, and between them and the dummy pattern 30b.
As a result, as shown in FIG.

In this case, the recesses 33a of the plate 33 are formed with the conductive patterns 2 located on both sides of the recesses 33a as described above.
8a and 28b, the sheet 2
The molten material of No. 9 infiltrates into the concave portion 33a and covers both sides of the conductive patterns 28a and 28b.

As a result, the adjacent conductive patterns 28a
, The effective insulation distance between 28b is increased.

Further, only by forming the concave portion 33a in the plate 33, a part of the sheet 29 can be moved between the conductive patterns 28a.
8b, it is possible to protrude toward the plate 33 and to cover both sides of the conductive patterns 28a, 28b, so that productivity can be increased.

The plate 33 has flexibility and heat resistance. When the plate 33 has flexibility as described above,
Since it is in close contact with the upper surface of the lead frame 30, the recess 33
a to the upper surfaces of the conductive patterns 28a and 28b outside
Will not be able to escape.

That is, since the electronic components and the like are mounted on the conductive patterns 28a and 28b as described above, if even those portions are covered with the outflow portion of the sheet 29, the electronic components cannot be mounted. Alternatively, since an extra operation such as a step of removing the outflow portion of the sheet 29 is required, these are prevented.

Further, when the plate 33 is formed of resin and a heat transfer material is mixed in the resin, the plate 3
The heat is easily transmitted to the lead frame 30 and the sheet 29 also from the third side, and as a result, the sheet 29 can be smoothly fluidized.

Further, from the viewpoint of heat conduction, the plate 33 may be formed of a metal plate, so that heat can be easily transmitted from the plate 33 to the lead frame 30 and the sheet 29. 29 can be fluidized smoothly.

Note that, on the dummy pattern 30b, FIG.
Thus, the dummy pattern 30b is easily peeled off from the sheet 29 because the projecting portion of the sheet 29 is not covered.

Since the inner surface of the concave portion 33a of the plate 33 is a mirror surface, a part of the sheet 29 flowing out between the conductive patterns 28a and 28b does not adhere firmly to the inner surface of the concave portion 33a. The peeling operation of the plate 33 can be smoothly performed.

Of course, a release agent may be applied to the inner surface of the concave portion 33a of the plate 33 so that a part of the sheet 29 does not firmly adhere to the inner surface of the concave portion 33a.

Further, if a ventilation hole penetrating upward is formed in the concave portion 33a of the plate 33, when a part of the sheet 29 flows between the conductive patterns 28a and 28b toward the concave portion 33a, the portion is formed in that portion. The existing air will be exhausted from this vent, and as a result, the sheet 29
Part of the flow can be performed smoothly.

Further, if the bottom surface of the concave portion 33a of the plate 33 is formed in a dome shape projecting upward on the opposite side to the lead frame 30, and a vent hole is formed in the center of the dome, air can escape more easily. A part of the sheet 29 is
Will smoothly penetrate into the concave portion 33a.

[0101]

As described above, the present invention comprises an insulating sheet and a lead frame superimposed on the sheet, and the lead frame has a plurality of conductive patterns. Is a configuration in which a sheet below the upper surface of the conductive pattern protrudes above the upper surface of the conductive pattern, and covers the side facing the other conductive pattern on the upper surface of at least one of the conductive patterns located on both sides thereof. is there.

With such a structure, the lower insulating sheet protrudes above the upper surface between the adjacent conductive patterns, and on the upper surface of at least one of the conductive patterns located on both sides thereof. , Because it covers the side facing the other conductive pattern, the effective insulation distance between adjacent conductive patterns is lengthened, which not only prevents short-circuiting between these adjacent conductive patterns, Accordingly, the distance between adjacent conductive patterns can be shortened, and the size can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an automobile adopting an embodiment of the present invention;

FIG. 2 is a configuration diagram of an electric circuit in the embodiment.

FIG. 3 is a circuit diagram showing a DC / DC converter and a write connection according to the embodiment;

FIG. 4 is a circuit diagram of a DC / DC converter according to the embodiment.

FIG. 5 is a plan view of the circuit board of the embodiment.

FIG. 6 is a sectional view of an essential part taken along line AB in FIG. 5;

FIG. 7 is a sectional view showing a manufacturing process of the circuit board.

FIG. 8 is a plan view of the same.

FIG. 9 is a sectional view of the same.

FIG. 10 is a sectional view of the same.

[Explanation of symbols]

 28A High-pressure side 28B Low-voltage side 28a Conductive pattern 28b Conductive pattern 29 Sheet 30 Lead frame 30b Dummy pattern 33 Plate 33a Depression Ta First distance Tb Second distance

Continued on the front page (72) Inventor Takeo Nagai 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. AA01 BA03 CB01 CC01 CC07 CC09

Claims (15)

[Claims] 1. An insulating sheet and a lead frame superposed on the sheet, the lead frame having a plurality of conductive patterns, and between the conductive patterns, a lower sheet is conductive. A circuit board that protrudes above the upper surface of the pattern and covers the side facing the other conductive pattern on the upper surface of at least one of the conductive patterns located on both sides thereof. 2. The lead frame is separated into a high-voltage side and a low-voltage side, and a distance between a high-voltage side conductive pattern and a low-voltage side conductive pattern adjacent to each other across the separation portion is defined as: 2. The circuit board according to claim 1, wherein the length is longer than between adjacent conductive patterns on the low voltage side. 3. The circuit board according to claim 2, wherein a concave portion is formed in a sheet in a separation portion on a high voltage side and a low voltage side of the lead frame. 4. An insulative sheet is superimposed on one of the front and back surfaces of the lead frame, and a plate body is polymerized on the other. Then, the three polymers are pressurized while being heated, and then the plate body is separated from the lead frame. In the method of manufacturing a circuit board to be formed, a concave portion facing the plate body side from the lead frame is formed on a portion of the plate body facing the lead frame on a portion facing between conductive patterns constituting the lead frame. The method for manufacturing a circuit board, wherein the recess is extended to at least one side of the plate body of the conductive pattern located on both sides of the recess. 5. The method according to claim 4, wherein the plate has flexibility. 6. The method for manufacturing a circuit board according to claim 5, wherein the plate body is formed of a resin, and a heat conductor is mixed in the resin. 7. The method according to claim 4, wherein the plate is formed of a metal plate. 8. The lead frame according to claim 4, wherein the high-voltage side and the low-voltage side are separated by a dummy pattern, and after the lead frame is integrated on the sheet, the dummy pattern is removed from the sheet. The method for manufacturing the circuit board described in the above. 9. The method of manufacturing a circuit board according to claim 8, wherein the dummy pattern is a non-covered portion of the projecting portion of the sheet. 10. A plurality of conductive patterns are respectively provided on the high voltage side and the low voltage side of the lead frame, and substantially the same first distance is formed between these conductive patterns and adjacent patterns among the dummy patterns. 9. The circuit board manufacturing method according to claim 8, wherein the sheet is integrated on the sheet using a lead frame, the sheet between the patterns at each adjacent first distance is raised to the upper surface of the conductive pattern, and then the dummy pattern is removed. 11. The circuit board manufacturing method according to claim 9, wherein the lower surface side of the low-voltage side and the high-voltage side conductive pattern of the lead frame has a rough surface, and the lower surface side of the dummy pattern has a non-rough surface. 12. The concave surface of the plate body having a mirror surface.
3. The method for manufacturing a circuit board according to claim 1. 13. The method for manufacturing a circuit board according to claim 4, wherein a release agent is applied to an inner surface of the concave portion of the plate body. 14. The method for manufacturing a circuit board according to claim 4, wherein a ventilation hole is formed in the concave portion of the plate body. 15. The method for manufacturing a circuit board according to claim 14, wherein the bottom surface of the concave portion of the plate body is formed in a dome shape protruding on a side opposite to the lead frame, and a vent hole is formed in the center of the dome.