JP2001177022A - Heat conduction board and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem such that an additional wiring is required because a conductor patterns must be formed in such an arrangement in which all the conductor pattern is connected to the outer frame of a lead frame when the wiring pattern of the lead frame is formed by a forming die in a usual punching process. SOLUTION: A lead frame provided with an optional conductor wiring pattern which is formed on its surface by etching by the use of a metal plate of certain thickness is buried in resin so as to solve the above problem, an insulator composed of thermosetting resin and inorganic filler is exposed at the part of lead frame on which the above conductor wiring is not present, conductor wiring patterns of separate shapes are contained in the above conductor wiring patterns, a metal plate for dissipating heat through the intermediary of the insulator is buried in the other surface, and the edge face of the metal plate is protected by an insulator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board having improved heat dissipation by a mixture of a resin and an inorganic filler, and more particularly to a heat conductive board used as a high heat dissipation resin board for mounting power electronics and a method of manufacturing the same. It is about.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become smaller, lighter, and higher in performance, higher density and higher functionality of electronic components such as semiconductors have been required. However, in circuit parts that generate heat, such as power conversion circuits, it is necessary to dissipate heat to the outside using heat sinks and radiating fins, making it extremely difficult to reduce the size and weight compared to other parts. I have. In response to this, the design of circuit boards taking heat dissipation into consideration has become important in recent years. As a technology to improve the heat dissipation of the circuit board, a metal board such as aluminum is used for a conventional glass-epoxy printed board, and a circuit pattern is formed on one or both sides of this metal board via an insulating layer. Metal-based substrates are known.

When higher thermal conductivity is required,
A board in which a copper plate is directly bonded to a ceramic board such as alumina or aluminum nitride is used, but a ceramic board is generally expensive and a metal base board is
Since the insulating layer is formed thin to improve heat conduction, there is a problem that stray capacitance is high and noise is easily transmitted. Similarly, in a metal base substrate, since a wiring pattern is formed by etching a copper foil having a thickness of about 35 μm, a large current cannot flow. For this reason, in the field of power electronics, these cannot be ignored as resistance loss, and will be a problem from the viewpoint of energy saving in the future.

In recent years, there has been proposed a heat conduction module by injection molding in which a composition in which a thermoplastic resin is filled with a heat conductive filler is integrated with a lead frame as an electrode. This substrate compensates for the above-mentioned metal base substrate and ceramic substrate, which are difficult to achieve in terms of performance and cost.

More specifically, this injection-molded heat conduction module has the characteristics of a metal base substrate having excellent mechanical strength and the characteristics of a ceramic substrate having good heat dissipation ( See JP-A-9-298344 and JP-A-9-321395. in addition,
In the case of a lead frame formed by punching a die, there is no circuit flexibility because a single land or a curved signal circuit cannot be formed.Therefore, a more flexible circuit formation is required by forming a lead frame by etching. ing.

[0006]

By the way, when a lead frame, a heat conductive sheet and a metal plate for a heat radiating plate are collectively formed, a process of etching is used to form a conductor wiring pattern of the lead frame on the heat conductive substrate. It is performed in. However, when a metal plate for heat dissipation is bonded to the opposite side of the buried lead frame, the end face of the metal plate for heat dissipation is etched in the step of etching the metal flat portion of the lead frame, which is performed to expose the conductive pattern. In addition, there has been a problem that an etchant intrudes into an interface where the metal plate and the heat conductive sheet and the metal surface thereof are in contact with each other, and inhibits the adhesion between the heat conductive sheet and the metal plate.

In order to solve the above-mentioned problem, there is a method of bonding a metal plate for a heat sink after forming a heat conductive substrate. However, since a heating and pressurizing step is added, productivity, cost and energy saving are increased. Etc. have problems.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a structure that does not corrode a heat-dissipating metal plate in an etching process and a simple manufacturing method.

[0009]

A lead frame according to the present invention is provided with an arbitrary island-shaped conductor wiring pattern on one surface by performing one-sided etching using a metal plate having a constant thickness. A wiring pattern including a groove having a uniform depth in the thickness direction in a portion other than the conductor wiring pattern on the one surface, and a flat surface on the other surface. I have.

In the above structure, the lead frame is
It is desirable to use a metal mainly composed of at least one selected from copper, iron, aluminum and nickel. This is because resistance loss can be reduced and a large current can be handled.

In the above structure, it is preferable that the lead frame is a uniform rolled plate having a thickness of 0.1 to 1.5 mm. This is because a larger current can flow than a thin copper foil of a conventional metal base substrate, and a fine wiring pattern can be formed.

In the above structure, the surface of the lead frame on which the conductor wiring pattern is formed is made of nickel,
It is desirable that the surface is plated with at least one of tin and a solder alloy, and / or that the surface is further roughened. This is because the adhesion with the insulating resin when molded and integrated can be further improved.

In the above structure, it is preferable that the groove having a uniform depth of the lead frame has a groove having a depth of 20 to 80% of a thickness of a metal plate having a constant thickness. If the depth is less than 20%, the surface has a long time to etch a metal plate having a flat surface, which is not economical. On the other hand, at 80% or more, the grooves between the wiring patterns become too deep, and it becomes difficult to accurately maintain independent island-shaped pattern positions. More preferably, 30 to 6
The depth is desirably 0%, and the etching time, the strength of the lead frame pattern, and the thickness of the embedded lead frame corresponding to a large current are within an appropriate range.

According to a method of manufacturing a lead frame according to the present invention, a wiring pattern including an arbitrary independent island-shaped conductor wiring pattern is formed on only one surface of a metal plate having a constant thickness by an etching method. On the other hand, a groove having a uniform depth in the thickness direction only on the surface and a conductor wiring pattern having a desired shape are formed.

In the above structure, it is preferable to add a step of plating or / and further roughening the surface of the conductor wiring pattern in addition to the step of removing the resist film. This is because there is an effect of increasing the adhesiveness between the lead frame and the insulating resin during molding.

Further, in the heat conductive substrate according to the present invention, a conductor wiring pattern made of a lead frame is buried on the surface, and an insulator made of at least a thermosetting resin and an inorganic filler is provided in a portion where the conductor wiring pattern does not exist. Are exposed and include the conductor wiring patterns each having an independent shape, and the other surface has a structure in which heat is radiated through the insulator.

In the above structure, when a metal plate for improving heat radiation characteristics is added to the surface of the insulating material opposite to the surface of the heat conductive substrate bonded to the lead frame, the size of the metal plate is buried in the insulating material. When the lead frame, the insulator and the metal plate are bonded to each other, the metal plate is embedded in the insulator by using the heat conductive substrate having a size smaller than the outer size of the heat conductive substrate by 0.5 mm or more. Thereby, the end face of the metal plate is protected by the insulator. Therefore, a desired flat metal portion can be removed without corroding the end face of the metal plate at the time of etching in the next step.
Preferably, the surface of the metal plate buried in the insulator is roughened. This is because the adhesion between the metal plate and the insulator is improved. Further, it is desirable to attach a protective film typified by polyethylene or vinyl chloride in advance on the surface of the metal plate opposite to the surface buried in the insulator.
It is used as a resist film when etching a flat metal plate and protects the metal surface.

In the above structure, it is preferable that the thickness of the insulating layer directly under the lead frame on the heat conductive substrate is in the range of 0.02 to 2 mm. If the thickness is 0.02 mm or less, the heat radiation surface of the substrate and the stray capacitance become large, and noise is easily transmitted. On the other hand, if the thickness of the insulating layer is 2 mm or more, the heat resistance increases, the heat radiation efficiency is extremely reduced, the temperature exceeds a predetermined component heat generation temperature, and in some cases, the semiconductor component may be broken.

Further, in the heat conductive substrate according to the present invention, a conductor wiring pattern made of a lead frame is buried on the surface, and an insulator made of at least a thermosetting resin and an inorganic filler is provided in a portion where the conductor wiring pattern does not exist. Are exposed and include the conductor wiring patterns each having an independent shape, and the other surface has a structure for radiating heat via the insulator, and the conductor wiring comprising the embedded lead frame. The pattern has a structure depressed from the surface of the insulator made of the thermosetting resin and the inorganic filler.

In the above structure, it is desirable that the thermosetting resin contained in the insulator made of a thermosetting resin and an inorganic filler is at least one of an epoxy resin, a phenol resin, and a cyanate resin. This is because even if the heat conductive substrate is exposed to a high temperature, it has excellent electrical insulation. In particular, thermosetting epoxy resins are excellent in not only electrical properties but also chemical resistance and mechanical performance, as is well known in semiconductor encapsulation resins and printed circuit boards.

In the above structure, the inorganic filler contained in the insulator comprising a thermosetting resin and an inorganic filler comprises at least one kind of powder selected from alumina, silica, magnesia, aluminum nitride and boron nitride. Is desirable. This is because various performances can be exhibited. That is, when alumina or aluminum nitride is used, a module having excellent thermal conductivity is obtained. In addition, magnesia has good thermal conductivity and can have a large thermal expansion coefficient. Furthermore, if it is silica (especially amorphous silica), a heat conductive substrate having a small coefficient of thermal expansion, light weight, and a small dielectric constant can be obtained.

Further, according to the present invention, there is provided a method for manufacturing a heat conductive substrate, comprising the steps of: forming an uncured sheet material for a heat conductive substrate comprising at least a thermosetting resin and an inorganic filler on the uneven surface of a lead frame on which a conductive wiring pattern is formed; Heating and heating under predetermined conditions to cure and bond to form an insulating layer, and etching the opposite metal plane bonded to the heat conductive substrate sheet until the insulating layer is exposed. It is obtained by doing. Thereby, a conductor wiring pattern is buried in the etched metal surface,
In addition, it has a structure in which a cured insulating material composed of at least a thermosetting resin and an inorganic filler is exposed in a portion where the conductor wiring pattern does not exist. At the time of this etching, the same pattern as the buried conductor wiring pattern is formed as a resist film on the opposite metal plane bonded to the heat conductive substrate sheet-like material, so that the conductor wiring pattern protruding from the insulator surface is formed. Can be formed.

In a similar manner, a resist film of the conductive pattern is selectively formed on the opposite metal surface bonded to the sheet material for a heat conductive substrate, so that the buried conductive pattern is formed on the insulating surface. More concave portions and convex portions can be arbitrarily manufactured.

In the above structure, it is desirable that the heating and pressurizing conditions be at least the curing temperature of the thermosetting resin composition in the sheet material for a heat conductive substrate and that the molding be performed at a pressure of 10 to 200 kg / cm ^2. . This is because the heat conductive substrate sheet-like material can be filled all over the unevenness of the lead frame surface and covers the end surface of the heat radiating plate.

In the above structure, the heating and pressurizing conditions are not more than the curing temperature of the thermosetting resin composition in the sheet material for a heat conductive substrate, and the molding is performed at a pressure of 10 to 200 kg / cm ² , and the lead frame is formed. The surface is filled and integrated, and then at a temperature not lower than the curing temperature of the thermosetting resin composition, an additional 10
Preferably, the method comprises a step of heating and pressurizing the thermosetting resin at a pressure of about 400 kg / cm ² to cure the thermosetting resin. This is because the irregularities of the lead frame can be filled at a curing temperature or lower and then heated and cured at a temperature higher than the curing temperature to be cured and adhered in a short time, and furthermore, become an insulator that can withstand a later etching solution.

As a result, compared with the conventional method of not protecting the end face of the heat sink, the end face is not corroded, and the etching liquid does not penetrate into the interface between the heat sink and the heat conductive sheet. The adhesive strength of the conductive sheet can be maintained. In addition, the end surface for the radiator plate is protected by the resin, and the radiator plate is buried in the resin, so that the resist film for protecting the radiator plate is easily formed.

[0027]

(Embodiment 1) Hereinafter, Embodiment 1 of the present invention will be described with reference to the drawings.

FIGS. 1A to 1F are process diagrams showing a method for manufacturing a lead frame according to the first embodiment of the present invention. In FIG. 1A, reference numeral 11 denotes a metal plate having good electrical conductivity. In consideration of thermal conductivity, the metal plate is made of, for example, a metal mainly containing at least one selected from copper, iron, aluminum, and nickel, and has a thickness of 0.1 to 1.5.
It is preferably a uniform rolled plate having a thickness of mm. In FIG. 1B, reference numeral 12 denotes a resist film. In FIG. 1C, the film pattern 13 shown on only one surface of the metal plate is aligned and arranged on the resist film 12. Here, the surface to which the film pattern is attached is exposed using UV. At this time, the entire surface on which the film pattern is not bonded is exposed.

Next, resist development is further performed. After exposure, the resist is hardened only at the exposed portion, and the non-exposed portion is removed by development, and is divided into an exposed portion 15 and a non-exposed portion 14 as shown in FIG. In FIG. 1E, FIG.
By etching the exposed surface of (d), a groove 16 having a uniform depth in the thickness direction and irregularities of the conductor wiring pattern having a desired shape are formed only on one surface of the metal plate.

Here, the etching depth is as follows.
20 thicknesses in the thickness direction of a metal plate having a constant thickness
It is desirable to have a groove with a depth of ~ 80%,
Generally, the thickness is set to half of the thickness of the metal plate. Finally, by peeling the resist film cured with caustic soda,
A lead frame as shown in FIG. 1 (f) is formed. Thereafter, it is also effective to add a step of plating the surface of the conductor wiring pattern and / or further roughening the surface.

In manufacturing the above lead frame,
A method of forming a resist film and forming a concavo-convex pattern using an etching method has been described.For example, a method of printing a reverse pattern corresponding to a wiring pattern by a screen printing method or the like and forming a pattern concavo-convex by a chemical etching method or Alternatively, the concave and convex grooves may be formed by a sandblasting method other than the etching method.

(Embodiment 2) FIGS. 2 and 3A to FIG.
(E) is a process diagram showing a method for manufacturing the heat conductive substrate in Embodiment 2 of the present invention. In FIG. 2A, the lead frame 21, the heat conductive sheet 22, and the heat sink 23 described in the first embodiment are prepared. The thermosetting sheet 22 can be formed by processing at least an uncured thermosetting resin and an insulator made of an inorganic filler into a sheet. The thermosetting resin contained in the present heat conductive sheet is made of at least one of an epoxy resin, a phenol resin, and a cyanate resin.

The inorganic filler is alumina, silica,
It is composed of at least one powder selected from magnesia, aluminum nitride and boron nitride. The addition amount of the inorganic filler is desirably about 70 to 95% by weight of the whole sheet-like material. However, in the case of a heat conductive substrate that requires good thermal conductivity, a high inorganic filler filling of 90% by weight or more is desirable. Further, the heat radiating plate 23 is preferably made of a metal such as copper, aluminum, nickel, and iron, and the size thereof is desirably 0.5 mm or smaller than the desired size.

In FIG. 2B, the lead frame 21
The uncured heat conductive substrate sheet 22 is laminated on the uneven surface on which the conductor wiring pattern is formed, and a heat radiating plate 23 is further laminated thereon. And a substrate is formed by bonding. At this time, the heat conductive substrate sheet-like material 22 is completely filled also in the concave portion of the concave and convex surface of the lead frame.

In FIG. 2C, a protective film 24 is adhered to a heat radiating plate 23 to form a sheet 22 for a heat conductive substrate.
By etching the opposite metal plane bonded to the insulating layer until the insulating layer is exposed, a conductor wiring pattern is buried in the etched metal surface, and a cured insulating material is provided in a portion where the conductor wiring pattern does not exist. A heat conductive substrate with the object exposed is produced.

At this time, even if an independent island pattern is formed by using the lead frame having the uneven shape, there is no problem that the end face of the heat radiating plate is corroded unlike the conventional case, and the completed heat conductive substrate is also used. An independent lead frame pattern is formed, and a shape in which the lead frame is buried can be realized. By burying the lead frame pattern, the heat can be dissipated not only from below the lead frame but also in the width direction of the lead frame, so that it is effective for a power supply module or the like that requires heat radiation.

Further, in the step shown in FIG.
When the metal plane on the opposite side bonded to the sheet material for a heat conductive substrate is etched until the insulating layer is exposed, the etching is further continued and the embedded lead frame is formed as shown in FIG. The conductor wiring pattern consisting of
By making the structure recessed from the surface of the insulator made of the thermosetting resin and the inorganic filler, it is possible to easily fix the position of the component when mounting the component. Also, because the insulating layer surface has a structure that protrudes from the lead frame pattern,
The edge distance between the wiring patterns can be increased.

In other words, this indicates that even if the distance between the wiring patterns is narrowed, the insulation distance can be secured as compared with the case where the wiring pattern is flat, so that high density can be achieved and the size of equipment such as a power supply can be reduced. Can contribute. Also,
In FIG. 3E, a solder resist 25 is formed by screen printing or the like after exposing the conductor wiring pattern after etching the metal plane. Thereby, the amount of solder at the time of mounting components is reduced, and the insulation of the circuit is improved.

(Embodiment 3) FIGS. 4 and 5A to FIG.
In FIG. 2D, in FIG. 2B, a case where a current capacity is required by a method of forming a thicker circuit using the same pattern film as the conductor wiring pattern buried in the plane of the metal plate, This is an effective means when forming a thick and narrow circuit. This is because, when a pattern is formed by etching, the portion where the etching resist is formed tends to be larger than the etching resist forming width as it becomes lower than the portion where the etching resist is formed. When the above-described groove is formed, the width of the lower conductor becomes wider than necessary.

Therefore, in this method, first, a lead frame on which a conductor wiring having a thickness of 50% is formed is manufactured, the conductor wiring is embedded in a heat conductive sheet, and then a film having the same pattern as the conductor circuit buried from a metal flat portion is formed. By using this, the same circuit is formed from the lower surface portion of the formed conductor wiring, so that a highly accurate conductor circuit without increasing the width of the circuit more than necessary can be obtained. In FIG. 4 (a), from FIG.
An etching resist is formed through coating or pasting of an etching resist, exposure, and development.
In FIG. 4B, an unnecessary metal plate is etched by etching to obtain a desired circuit.

In FIG. 5C, from FIG.
In order to arbitrarily form circuits having different conductor thicknesses on a metal plane, an etching resist is formed by applying or attaching an etching resist, exposing, and developing with a film. In addition, FIG. 5D shows a case where the conductor thickness is arbitrarily manufactured by etching.

[0042]

Hereinafter, the present invention will be described in more detail with reference to specific examples.

(Example 1) When manufacturing the lead frame of the present invention, a copper plate (manufactured by Kobe Steel: KFC 1/2) having a thickness of 1.0 mm was prepared as the metal plate 11 having a constant thickness. In order to form a resist film having an arbitrary pattern shape on one surface of a metal plate 11 having a constant thickness, a resist film 12 was formed on both surfaces of the metal plate by a roll laminating apparatus using a dry film resist. The dry film resist is a general one used for patterning a printed board (dry film resist: H-S930-30 manufactured by Hitachi Chemical Co., Ltd.).

Next, the metal plate 11 having the dry film 12 formed on both sides was subjected to close-contact exposure through a film mask 13 on which a wiring pattern was drawn, using an ultraviolet exposure apparatus. The entire surface of the metal plate on which the wiring pattern was not formed was exposed. Next, the exposed dry film resist on the metal plate 11 is processed in a developing solution, and the exposed resist portion is cured by ultraviolet rays and remains, but the resist not exposed by the film mask is removed, and the metal resist is removed. The plate surface is exposed.

Further, the resist film is etched in an iron chloride solution to form a groove having a uniform depth in a thickness direction and a desired convex portion only on one surface of the metal plate. A conductor wiring pattern was formed. At this time, the depth of the groove formed in the metal plate having a certain thickness can be controlled by changing the etching time. In this embodiment, for a metal plate having a thickness of 0.5 mm,
Approximately half of the groove was formed with a depth of 0.5 mm.

Finally, the resist film was removed by treating it with caustic soda, thereby producing a lead frame having irregularities on the surface having a pattern independent of an arbitrary wiring pattern.

(Example 2) When manufacturing the lead frame of the present invention, a 0.5 mm thick copper plate (manufactured by Kobe Steel: KFC 1/2) was prepared as the metal plate 11 having a constant thickness. A resist film having an arbitrary pattern shape is formed on one surface of a metal plate 11 having a constant thickness. The resist film can be obtained by printing a resist paste by a screen printing method. The resist paste used was a mixture of butyral resin and terpineol as a binder.
Printing was performed on the surface of the metal plate 11 by a squeegee using a screen plate on which an arbitrary pattern was formed. The metal plate on which a resist film is formed in this manner is formed at 100 ° C.1
The solvent was dried by a zero-time drier. After drying, a butyral resin film (thickness: about 30 μm) was formed. On the other hand, on the other side, resist printing and drying were similarly performed on the entire surface.

Next, an etching process is performed in an iron chloride solution using the resist film to form a groove having a uniform depth in a thickness direction and a desired convex portion only on one surface of the metal plate. A conductive wiring pattern was formed. At this time, the depth of the groove formed in the metal plate having a certain thickness can be controlled by changing the etching time. In this embodiment, for a metal plate having a thickness of 0.5 mm,
Approximately half of the groove was formed with a depth of 0.25 mm.

Finally, the butyral resin was dissolved and removed from the resist film using a solvent, and the surface thereof was nickel-plated, whereby a lead frame having irregularities having a pattern independent of an arbitrary wiring pattern on the surface was produced. . Further, the surface of the uneven portion is roughened by sand blasting by spraying alumina powder on the surface, thereby making it possible to enhance the adhesion to the thermosetting resin.

(Example 3) In producing the heat conductive substrate of the present invention, a method of producing a sheet material using an inorganic filler and a thermosetting resin will be described first. In the method for producing a sheet-like material used in this example, an inorganic filler, a liquid thermosetting resin, and an appropriate solvent are mixed by a stirring mixer. The stirring and mixing machine used is an apparatus in which an inorganic filler, a liquid thermosetting resin and a solvent are charged into a container having a predetermined capacity, and revolves while rotating the container itself. It is obtained. The composition of the sheet material for the heat conductive substrate was as follows. The epoxy resin as the liquid thermosetting resin was manufactured by Nippon Pernox Co., Ltd. (WE-2025, including an acid anhydride-based curing agent). Ink Co., Ltd. (Phenolite VH4150), and the cyanate resin used was Asahi Ciba Co., Ltd.'s (AroCy M-30).

As a specific method for producing a sheet-like material, a predetermined amount of a paste-like mixture weighed and mixed according to the composition shown in Table 1 is taken and formed on a release film. As the release film, a polyethylene terephthalate film having a surface having a thickness of 75 μm and subjected to release treatment with silicon was used. The kneaded material was formed into a constant thickness by a doctor blade method. Next, the mixture on the release film was heated together with the release film, and dried and heat-treated under the condition that tackiness was lost. The heat treatment is performed at a temperature of 120 ° C. for 15 minutes. As a result, the mixture becomes a non-sticky sheet having a thickness of 500 μm. Since the thermosetting epoxy resin has a curing start temperature of 130 ° C., it is in an uncured state (B stage) under the heat treatment conditions, and can be melted again by heating in a subsequent step.

The sheet-like material produced in this manner is superposed on the lead frame produced in Example 1 so that the concave and convex surfaces thereof face each other, and is then 0.5 mm or less smaller than the desired size. Heat sinks are overlapped and sandwiched between two flat metal plates of 10 mmt.
It was heated and pressed at a pressure of 50 kg / cm ² at 50 ° C. At this time, the above-mentioned sheet-like material flows into the uneven surface of the lead frame and is completely filled, and the thermosetting resin in the sheet-like material is cured by heating and is mechanically adhered to the lead frame, and the end surface of the heat radiating plate. The sheet-like material also flows in and covers.

(Example 4) An integrated substrate of a sheet and a lead frame manufactured in this manner was treated with an iron chloride solution (an iron chloride solution was used as an etching solution, but a copper chloride solution was used. The metal surface of the lead frame is subjected to an etching process by inserting the metal into the substrate. First, before this process, a metal surface serving as a heat sink is protected for corrosion during etching. As a resist film,
Protective film for acid resistance (NITTO TA manufactured by Nitto Denko)
PE No. 31) were bonded together so that air and the like did not enter between the metal surface. At the time of laminating, it was also possible to use a laminator machine for laminating commonly used films. After that, when an arbitrary conductor circuit is formed on the metal surface to be etched, a resist which is to be a resist at the time of etching is formed on the metal plate. This time, after laminating the dry film resist (H-S930-30 manufactured by Hitachi Chemical Co., Ltd.) also used in the first embodiment, exposure with a desired film is performed, followed by development and etching to form a desired conductor wiring. . For this pattern formation, it is possible to use the resist formation by screen printing of the second embodiment. By performing this etching until a sheet-like material other than a portion where an arbitrary conductor wiring is formed appears on the surface, a conductor wiring buried in the sheet-like material and an arbitrary conductor wiring pattern can be obtained on the upper portion thereof. Then, the etching resist formed above was removed with caustic soda to obtain a substrate on which a pattern was formed on a sheet-like material.

If there is no need for conductor wiring or the like on the metal surface, an etching process is performed without performing the above process. The etching process on one surface of the lead frame metal plate is performed at least until the sheet-like material appears on the surface. As a result, a heat conductive substrate having a flat wiring pattern in which only the protrusions of the lead frame were buried in the sheet was obtained. At this time, by further increasing the etching time, it is possible to obtain a heat conductive substrate having a structure in which the embedded lead frame is recessed from the surface of the sheet. Such a heat conductive substrate having a structure in which a wiring pattern is depressed is effective for positioning components in component mounting in a later process.

(Example 5) Since the copper wiring was exposed in a state where the copper wiring was formed on the sheet-like material in the above-described substrate, a solder resist was used to protect the conductive wiring. To form

This solder resist is a thermosetting solder resist ink (manufactured by Taiyo Ink Mfg. Co., Ltd .: S-22).
After 2) is formed by screen printing, the resist is cured at 150 ° C., 2 ° C. using a hot air drier.
By performing the treatment for 0 minutes, a substrate in which the conductor circuit wiring was protected by the solder resist was obtained.

[0057]

As described above, the substrate can be manufactured without corroding the end surface of the heat-dissipating metal plate obtained from the present invention. Further, according to the lead frame, the conductor wiring pattern portion for positioning is unnecessary, It is possible to produce a conductor wiring pattern having an arbitrary shape and no connection portion with another frame portion. Further, according to the present invention, it is possible to obtain a circuit board which is excellent in heat dissipation and has a high degree of freedom in pattern design, and enables circuit wiring of up to three different thicknesses on the same board. Furthermore, since the heat conductive substrate obtained from the present invention can eliminate resin burrs on the lead frame, it is considered to be an effective means even in consideration of a post-process such as component mounting.

[Brief description of the drawings]

FIG. 1 is a process sectional view illustrating a method for manufacturing a lead frame according to Embodiment 1 of the present invention;

FIG. 2 is a process sectional view showing a manufacturing process of a heat conductive substrate manufactured using a lead frame according to a second embodiment of the present invention.

FIG. 3 is a process sectional view of Embodiment 2;

FIG. 4 is a process cross-sectional view showing a process of manufacturing a heat conductive substrate having conductor circuits having different thicknesses according to the third embodiment of the present invention.

FIG. 5 is a process sectional view of Embodiment 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Metal plate 12 Resist film 13 Film pattern 14 Non-exposed part 15 Exposure part 16 Groove 21 Lead frame 22 Heat conductive sheet 23 Heat dissipating metal plate 24 Heat dissipating metal plate protection film 25 Solder resist

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/20 H01L 23/36 C (72) Inventor Seiichi Nakatani 1006 Kadoma, Kazuma, Kadoma, Osaka Matsushita Electric Industrial Inside (72) Inventor Yasuhiro Sugaya 1006 Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. (72) Inventor Mitsuhiro Matsuo 1006 Odaka Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. F-term (reference) 5E338 AA16 AA18 BB02 BB19 BB61 BB63 BB71 BB75 CC01 CD01 CD33 EE02 5E339 AB02 AC02 AD01 BC01 BD03 BD06 BE11 CE15 EE10 FF03 5E343 AA02 AA12 AA22 AA38 BB02 BB03 BB21 BB66 DD52 DD36 GG21 5

Claims (16)

[Claims] 1. A lead frame on which an arbitrary conductive wiring pattern is formed by etching from a metal plate having a certain thickness is buried on the surface, and at least a thermosetting resin is formed in a portion where the conductive wiring pattern does not exist. An insulator made of an inorganic filler is exposed, the conductor wiring pattern includes the conductor wiring pattern having an independent shape, and a metal plate for radiating heat via the insulator is embedded on the other surface. A heat conductive substrate having a structure in which an end face of a metal plate is protected by an insulator. 2. The distance between an end face of a metal plate buried for heat dissipation of the heat conductive substrate and an end face of the heat conductive substrate is 0.
The heat conductive substrate according to claim 1, wherein the heat conductive substrate has a length of 5 mm or more. 3. The heat conductive substrate according to claim 1, wherein a portion other than a land portion for connecting an electronic component to the conductor wiring pattern of the heat conductive substrate is protected by an insulating resist. 4. A conductor wiring pattern for protecting a conductor wiring pattern of the heat conductive substrate other than a land portion for connecting an electronic component with an insulating resist.
4. The heat conductive substrate according to claim 3, wherein the insulating resist has a configuration in which an opening has a diameter smaller by 2 mm. 5. A metal plate for improving heat radiation characteristics is provided on the surface of the insulator opposite to the surface of the heat conductive substrate which is bonded to the lead frame, at least one of a metal plate carried from copper, aluminum, nickel, and iron. The heat conductive substrate according to claim 1, wherein the heat conductive substrate is made of a metal mainly composed of: 6. The heat conductive substrate according to claim 1, wherein the thickness of the insulating layer immediately under the lead frame in the heat conductive substrate is in a range of 0.02 to 2 mm. 7. The heat conductive substrate according to claim 1, wherein
A heat conductive substrate, wherein a conductor wiring pattern made of the embedded lead frame has a structure depressed from the surface of an insulator made of the thermosetting resin and an inorganic filler. 8. The heat conductive substrate according to claim 1, wherein:
A heat conductive substrate, wherein the conductor wiring pattern made of the embedded lead frame has a structure protruding from the surface of an insulator made of the thermosetting resin and the inorganic filler. 9. The heat conductive substrate according to claim 1, wherein
A heat conductive substrate, wherein a conductor wiring pattern made of the embedded lead frame has a structure selectively depressed from the surface of an insulator made of the thermosetting resin and an inorganic filler. 10. The thermosetting resin contained in the insulator composed of a thermosetting resin and an inorganic filler is an epoxy resin,
The heat conductive substrate according to claim 1, wherein the substrate is at least one of a phenolic resin and a cyanate resin. 11. The method according to claim 1, wherein the inorganic filler contained in the insulator comprising a thermosetting resin and an inorganic filler comprises at least one powder selected from alumina, silica, magnesia, aluminum nitride, and boron nitride. The heat conductive substrate according to claim 1, wherein: 12. A step of forming a resist film having an arbitrary pattern on one surface of a metal plate having a constant thickness;
Next, etching using the resist film, forming a groove having a uniform depth in the thickness direction only on one surface of the metal plate and a conductive wiring pattern having a desired shape, A heat conductive substrate sheet made of at least an uncured thermosetting resin and an inorganic filler and a metal plate for a heat radiating plate are formed on the uneven surface of the lead frame formed by the step of removing the resist film on which the conductive wiring pattern is formed. Heating and pressurizing under predetermined conditions to fill and protect, cure, cure and bond the sheet-like material into the concave portion in which the conductor wiring pattern is formed and the end face of the metal plate to form an insulating layer; The step of etching the lead frame metal plane of the heat conductive substrate to which the conductive substrate sheet and the metal plate are bonded until the cured sheet is exposed. Accordingly, the conductor wiring pattern of the lead frame is buried in the heat conductive substrate sheet-like material, and the cured insulating material composed of at least a thermosetting resin and an inorganic filler is exposed in a portion where the conductor wiring pattern does not exist. A method for manufacturing a heat conductive substrate, wherein a portion other than a land to which an electronic component is joined in a separated state is protected by an insulating resin. 13. The method for manufacturing a heat conductive substrate according to claim 12, wherein the lead frame, the sheet material for the heat conductive substrate, and the heat dissipating metal plate are collectively heated and press-bonded, and then the lead frame is bonded. A step of forming a resist film having a pattern similar to an arbitrary conductor pattern formed on the lead frame on a metal plane, and then performing etching using the resist film, thereby embedding in the heat conductive sheet-like material. Forming a configuration in which the conductor wiring pattern is more convex than the heat conductive sheet-like material. 14. The method for manufacturing a heat conductive substrate according to claim 11, wherein the lead frame, the sheet material for the heat conductive substrate, and the metal plate for heat radiation are heated and pressurized and bonded.
Forming a resist film having a pattern selectively similar to an arbitrary conductor pattern formed on the lead frame on the lead frame metal plane, and then performing etching using the resist film, thereby achieving the heat conduction. Selectively forming a configuration of a conductor wiring pattern recessed from the heat conductive sheet material with the conductor wiring pattern embedded in the sheet material. 15. The method according to claim 1, wherein the heating and pressurizing are performed at a temperature equal to or higher than the curing temperature of the thermosetting resin composition in the heat conductive substrate sheet and at a pressure of 10 to 200 kg / cm ^2. The method for manufacturing a heat conductive substrate according to claim 12. 16. The conditions of the heating and pressurizing are not higher than the curing temperature of the thermosetting resin composition in the heat conductive substrate sheet and are molded at a pressure of 10 to 200 kg / cm ² , and the surface of the lead frame is formed. Filled and integrated, and then 10 to 400 kg at the curing temperature of the thermosetting resin composition or higher.
The method according to claim 12, comprising a step of curing the thermosetting resin by heating and pressurizing at a pressure of / cm ² .