JPH0745618A - Substrate and method for transferring electric conductor - Google Patents

Abstract

PURPOSE:To obtain a substrate which can easily form contacts for electrical connection with high accuracy on semiconductor elements, electronic parts, etc., by holding conductors having projecting sections protruded in a recessed section for setting an object to be transferred formed on an insulating film in through holes formed through the internal surface of the recessed section in the thickness direction in a removable state. CONSTITUTION:Conductors 2 having projecting sections 2a protruded in a recessed section 8 for setting an object to be transferred formed on an insulating film 1 are held in through holes 9 formed through the internal surface of the section 8 in the thickness direction in removable states. It is preferable that the film 2 has appropriate flexibility and transparency, because the conductors 2 can be easily aligned at the time of transferring the conductors 2. In addition, it is preferable to form the film 1 of a polyimide resin, because the heat resistance and mechanical strength of the film 1 can be improved. In addition, it is preferable to form the conductors 2 of solder, etc., having a low melting point so that the conductors 2 can easily melt and adhere to the section to be transferred of the object to be transferred when the conductors 2 are heated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate capable of transferring a conductor having a protrusion useful for electrical connection of a multilayer wiring board and a method for transferring the conductor having the protrusion.

[0002]

2. Description of the Related Art With the development of the semiconductor industry, electronic devices have become thinner, smaller and lighter, and for devices and equipment that use a lot of semiconductor devices, it is necessary to mount the semiconductors on a substrate having a certain area with high density. Is required. When mounting semiconductors, metal projections (hereinafter referred to as bumps) on semiconductor elements
Is directly or transferred to form a connection terminal, which is used for mounting. As a method of forming such bumps, application to various electric / electronic components other than semiconductor elements leads to improvement in mounting density in electronic devices.

[0003]

However, in general, it is difficult to directly form bumps on a semiconductor element and many other electronic components from the viewpoint of manufacturing technology (forming technology), and this is a cause of reduction in yield during manufacturing. It will be. On the other hand, a so-called transfer bump forming method has been proposed in which bumps are formed by a transfer method.
In the method of forming bumps on O glass, there are various restrictions on the manufacturing cost, manufacturing method, bump transfer method, etc.
It is not yet satisfactory in terms of practical application. The present invention is
An object of the present invention is to provide a base material for transferring an electric conductor, which can form an electrical connection contact with high accuracy in a semiconductor element, various electric / electronic parts, electric circuits, etc. easily. Another object of the present invention is to provide a transfer method capable of easily transferring contacts for electrical connection to semiconductor elements, various electric / electronic parts, electric circuits, and the like.

In the present invention, the semiconductor element may be a semiconductor element assembly (such as a silicon chip after dicing), a semiconductor device mounting circuit board, an LCD circuit board, a fine pitch circuit board such as a hybrid IC. In addition, the electric circuit represents a broad concept including not only a wiring pattern but also electrodes, leads and the like.

[0005]

According to the present invention, there is provided a substrate for transferring a conductor, wherein a protrusion is formed in a through hole penetrating an inner surface of a transfer member fitting recess formed in an insulating film in a thickness direction. And a through hole having a taper, and the insulating film has a thermoplastic resin layer or a metal layer on its non-recessed surface. A support layer made of, and a support layer is formed by laminating a metal layer on the thermoplastic insulating resin layer as necessary, and the metal layer penetrates the metal layer in the thickness direction. Micro through holes are formed so as to communicate with the joint surface between the end face of the conductor and the metal layer, and the conductor is made of a metal having a low melting point.

In the method of transferring a conductor of the present invention, the member to be transferred is fitted in the concave portion of the base material for transferring the conductor and heated and / or pressurized to transfer the conductor to the processing position of the member to be transferred. After removing the insulating film of the base material, or by fitting the transfer target to the recess of the conductor transfer base material holding the conductor made of a metal having a low melting point, heat it to lower it. It is characterized in that a metal having a melting point is melted and separated from a base material at a predetermined position of a transfer target.

[0007]

According to the substrate for transferring a conductor of the present invention, a recess is formed in the insulating film in such a size that the transferred member can fit into the insulating film.
Since the conductor is detachably held in the through hole corresponding to the conductor transfer position of the transfer target formed on the inner surface of the recess, the conductor can be accurately transferred to the conductor transfer position of the transfer target. Like In addition, a conductor having a protrusion at one end is detachably held in a through hole formed in the concave portion of the insulating film, and the protrusion of this conductor is transferred to the conductor transfer position of the transfer target. Therefore, the conductor can be easily and stably transferred.

Further, according to the conductor transfer method of the present invention, the conductor can be transferred onto the electrode of the transfer target simply by fitting the transfer target in the concave portion of the conductor transfer base material. ,
It eliminates the need for precise alignment and improves the efficiency of conductor transfer work.

[0009]

EXAMPLES Examples will be given below to explain the present invention in detail, but the present invention is not limited to these examples. FIG. 1 is a schematic cross-sectional view showing the structure of a conductor transfer base material according to an embodiment of the present invention. In the figure, K is a conductor transfer base material, and a concave portion 8 is formed on one surface of the insulating film 1, and a through hole 9 penetrating the insulating film in the thickness direction is formed in the concave portion 8. , The through hole 9 is provided with the conductor 2 having the protrusion 2a at one end,
The protrusion 2 a is held in the recess 8 by protruding.

Insulating film 1 for the conductor transfer substrate
As long as it has electrical insulation, it is preferable that it has appropriate flexibility. In particular,
Thermosetting or thermoplasticity of polypolyester resin, epoxy resin, urethane resin, polystyrene resin, polyethylene resin, polyamide resin, polyimide resin, ABS resin, polycarbonate resin, silicone resin, fluorine resin, etc. Any type of resin can be used.

In the present invention, it is preferable to use a transparent resin among the above resins, because the positioning becomes easy when the conductor is transferred. Further, it is preferable to have a polyimide resin because heat resistance and mechanical strength can be obtained. The thickness of the insulating film is not particularly limited, but the base material is flexible.
˜500 μm, preferably about 12 to 200 μm.

The recess 8 is formed in conformity with the shape of the transferred body such as a semiconductor element or an electric component to be fitted, but it is usually formed larger than the size of the transferred body by about 10 to 100 μm. The depth is not particularly limited, but it is preferably at least 20 μm in order to prevent the transferred body from easily moving when fitted.

The through hole 9 is formed at a position corresponding to the conductor transfer portion of the transfer target body fitted in the recess 8. In the present invention, the shape of the through hole 9 is not particularly limited, but as shown in the partially enlarged sectional view of FIG.
It is preferable that the through hole 9a is formed in a taper whose opening width is widened toward the concave portion 8 and the conductor 2 is held in the through hole 9a because the conductor 2 is easily separated from the insulating film 1. . The taper angle is preferably such that the angle between the thickness direction of the insulating film and the taper direction of the through hole is 20 ° or less, preferably about 5 to 15 °. If the taper angle exceeds 20 °, it becomes difficult to hold the conductor, which is not preferable. Further, in the present invention, FIG.
As shown in the schematic cross-sectional view of FIG. 5, the tapered through hole 9b may have a stepped shape.

The conductor 2 held in the through hole 9 may be solder, gold, silver, copper, nickel, tin, indium, or an alloy composed of a combination of two or more of these. Of these, solder having a particularly low melting temperature, such as solder having a low melting point, is preferable because it can be easily melted by heating and fixed to the transfer portion of the transfer target.

In the present invention, the conductor 2 has a protrusion formed on at least one end. The height of the protrusion of the conductor is not particularly limited, but it is preferably about several μm to several tens of μm. The shape may be, for example, mushroom (umbrella) or hemisphere, prism, cylinder, sphere, cone (cone, pyramid).
May be Further, the end face shape of the conductor may be a triangle, a square, a rectangle, a trapezoid, a parallelogram, or another polygon. In the present invention, the protrusions can be formed on both ends of the conductor.

By using the conductor shape having the above-mentioned protrusions, positioning can be facilitated during transfer, and the conductor can be stably and reliably transferred to the transfer position of the transferred body.

In the present invention, the conductor 2 may have a multi-layer structure in which different kinds of metals are coated. Figure 4
FIG. 3 is a schematic cross-sectional view showing this example, in which the metal body layer 10 suitable for joining to the transferred body is formed on the surfaces of both ends of the conductor 2.
2, 202 are formed. With the above configuration, the conductor 2 can be provided with a desired surface texture. For example, when the conductor 2 is used as a contact to which pressure is repeatedly applied, or when the conductor 2 is pressed into the electrode portion of the transfer target and bites into it, a relatively hard metal such as nickel is used as the metal layers 102 and 202. In the case where a layer is formed and the conductor 2 is melted by heating to be fused to the electrode portion of the transferred body, the metal layer 102, 202 is made of metal having a relatively low melting point such as gold or solder. A layer may be formed. The multi-layer structure may be formed on one end surface of the conductor on the transfer side.

The conductor transfer substrate of the present invention is shown in FIG.
1 is manufactured by the method shown in the schematic diagram. First, Fig. 1
As shown in FIG. 1A, the metal layer 3 is formed on one surface of the insulating film 1 to prepare a base material. Then, half-etching is performed on the insulating film 1 of the base material, and FIG.
As shown in FIG. 5, the recessed portion 8 is formed in conformity with the shape of the transferred material. As the half etching method, mechanical processing, laser processing, optical processing, chemical etching or the like can be used, but it is preferable to use ablation processing with an ultraviolet laser such as an excimer laser having a large degree of freedom in the shape of the recess and the depth. .

As shown in the schematic cross-sectional view of FIG. 5, the recess 8 is formed by laminating the insulating film 1a punched out in accordance with the shape of the transferred material on the insulating film 1. You can As the bonding method, a method of using an adhesive, a method of heat fusion using a thermoplastic resin as an insulating film, and the like can be used. Further, as the punching method of the insulating film, press working, chemical etching, a method of dissolving a non-photosensitive region by using a photosensitive resin, or the like can be used.

Then, as shown in FIG. 11C, a through hole 9 reaching the metal layer 3 is formed in the insulating film 1 in the recess 8.
To form. The through hole 9 is formed corresponding to the conductor transfer position in the transfer target body fitted in the recess 8.
As a method of forming the through hole 9, a method of using an ultraviolet laser such as an excimer laser, which has a large degree of freedom of fine processing property and a processed shape, a method of dissolving a non-photosensitive region by using a photosensitive resin in an insulating film, etc. Is preferred.

Next, the above-mentioned base material is immersed in a metal plating bath, and normal electrolytic plating is performed between the counter electrode and the metal layer 3 as an electrode, and as shown in FIG. Then, a metal is deposited and filled to form the conductor 2. At this time, the protrusion 2a can be formed by plating until the deposited metal protrudes on the surface of the insulating film.

Finally, when the metal layer 3 of the base material is removed by etching, as shown in FIG. 11 (e), the inner surface of the recess 8 for fitting the transferred body formed in the insulating film 1 is penetrated in the thickness direction. In the through hole 9, a conductor transfer base material K for detachably holding the conductor 2 having the protrusion 2a protruding into the recess 8 is manufactured.

Since the metal layer 3 is removed by etching as described above, the metal constituting the conductor 2 is
It is preferable to use a metal whose solubility is different from that of the metal layer 3. Further, in forming the concave portion of the insulating film, the punched insulating film 1a is attached to the insulating film 1 before the formation of the conductor 2, but the insulating film 1a is attached after the formation of the conductor 2. It can be carried out.

According to the conductor transfer substrate having the above structure, the insulating film is provided with a recess having the size of the transfer target, and the inner surface of the recess has a through hole corresponding to the transfer position of the conductor on the transfer target. Since the transfer conductor is detachably held in the through hole, the conductor can be accurately transferred to the transfer position of the transfer target. Further, since the through hole is formed to have a taper so that the conductor can be detachably held, the conductor can be accurately and easily transferred.
In addition, a protrusion, especially a mushroom-shaped protrusion, is formed at one end of the conductor, and this protrusion is transferred to the transfer target, which facilitates alignment and ensures stable transfer of the conductor. become.

FIG. 6 is a schematic sectional view showing a preferred constitutional example of the conductor transfer base material of the present invention. In the figure, the difference from FIG. 1 is that the support layer 3 is provided on the surface of the insulating film 1 opposite to the recess forming surface. As the support layer, a metal layer made of copper, gold, nickel, aluminum, chromium, iron or an alloy thereof is suitable. The support layer 3 is formed by bonding a metal foil to a conductor transfer base material via an adhesive. Specifically, apply an adhesive to the metal foil,
Alternatively, a metal foil laminated with an adhesive film is attached to a predetermined position of the conductor transfer base material, or a metal foil is vapor-deposited on the adhesive film to form a predetermined conductor transfer base material. Formed by laminating in position. In the present invention, the thickness of the support layer 3 is set to 10 μm in order to suppress deformation due to heat or pressure during lamination.
It is preferably m or less.

In the present invention, the support layer 3 has wettability with the conductor so that the conductor can be easily separated from the conductor transfer base material when the conductor is transferred to the transfer target. Is preferably inferior. For example, when the conductor is solder, the metal layer is preferably nickel, chromium or stainless steel containing these metals. When the metal layer is a metal having good wettability with the conductor, it is preferable to provide the metal layer with poor wettability with the conductor at the interface between the two.

With the structure in which the support layer is provided, the rigidity and flatness of the transfer base material are improved, and thus the transfer work efficiency is improved. Further, the metal layer and the conductor are bonded with a low adhesive force, and the conductor can be prevented from falling off from the conductor transfer base material. Furthermore, by forming a metal layer on the base material after transfer of the conductor, the base material holding the conductor can be reused.

FIG. 7 is a schematic sectional view showing another embodiment for forming the metal layer. The difference from FIG. 6 is that the support layer is a multi-layer of the thermoplastic resin layer 4 and the support layer 3. The thermoplastic resin layer, a thermoplastic resin solution is applied onto the insulating film, or a thermoplastic resin film is laminated, and the thermoplastic resin solution is applied onto the metal layer, or a thermoplastic resin film is applied. It can be laminated, or the thermoplastic resin film can be formed by laminating an insulating film on one surface and a metal layer on the other surface.

According to the above construction, the rigidity and flatness of the transfer substrate can be further improved, and the transfer work efficiency can be improved. Also, on the base material after the conductor transfer,
By forming the thermoplastic resin layer and the metal layer again,
Since the conductor transfer base material can be manufactured, the base material holding the conductor can be reused.

FIG. 8 is a schematic sectional view showing another embodiment of the present invention. The difference from FIG. 6 or FIG. 7 is that
The metal layer 3 is provided with a minute through hole 7 communicating with an end surface of the conductor 2 and a joint surface between the metal layer 3. When the conductor is transferred to the transfer target using the transfer substrate of the present invention, the minute through holes 7 act as air vents, and the conductor is easily separated from the substrate. The micro through-hole 7 is not particularly limited as long as it has a shape and size capable of removing the air, but in the present invention, the diameter of the micro through-hole is the end surface diameter of the conductor that contacts the metal layer. It is preferably 1/2 or less. Further, the number of the minute through holes may be one or plural.

FIG. 9 is a schematic cross-sectional view showing an embodiment of the method of the present invention. Using the conductor transfer substrate K shown in FIG. 1, semiconductor devices, various electric / electronic parts, etc. can be coated. A method for transferring a conductor to an electrode surface of a transfer body will be described. First, as shown in FIG. 9A, the transfer target 10 is fitted in the recess 8 of the conductor transfer base material K. The recess 8 of the conductor transfer base material K is formed in conformity with the shape of the transfer target 10, and the conductors 21, 22 are formed in the recess 8 at positions corresponding to the electrode portions 15, 16 of the transfer target 10. Because it is held
The electrode part 1 of the transferred body does not require precise alignment.
The conductors 21 and 22 of the conductor transfer base material K are located on the conductors 5 and 16.

Next, the conductor transfer base material K is heated and / or pressurized while the transfer target 10 is fitted. By this treatment, for example, if a metal layer that melts at a low temperature or a metal layer that has good wettability with respect to the conductor 2 is formed in the electrode parts 15 and 16, heating and / or pressurization at the time of bonding As shown in FIG. 9 (b), the conductor 2
The electrodes 1 and 22 can be easily joined to the electrode portions 15 and 16. Further, after the conductor is joined to the electrode portion,
As shown in (c), when the insulating film 1 of the base material holding the conductor is moved in the arrow direction, the conductor 21,
22 is accurately and easily transferred to the electrode portions 15 and 16.

In the above-mentioned conductor transfer method, when a low melting point metal is used as the conductor 2, the conductor 2 is melted by heating only as shown in the schematic sectional view of FIG. Since it comes off from the insulating film 1 and is fused to the electrode portion 15, the operation of moving the base material can be omitted, which is preferable.

[0034]

As described above in detail, according to the conductor transfer substrate of the present invention, a recess is formed in the size of the transfer target, and the conductivity of the transfer target is formed on the inner surface of the recess. Since the conductor is detachably held in the through hole corresponding to the body transfer position, the conductor can be accurately transferred to the conductor transfer position of the transfer target. In addition, the through hole formed on the inner surface of the recess of the insulating film allows the projection to project on the inner surface of the recess to hold the conductor detachably, and the projection of the conductor is positioned at the conductor transfer position of the transfer target. Since the transfer is performed, the conductor can be easily and stably transferred.

Further, according to the conductor transfer method of the present invention, the conductor can be transferred onto the electrode of the transfer target by simply fitting the transfer target into the recess of the conductor transfer base material. ,
Precise alignment is not required and the efficiency of conductor transfer work is improved.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the structure of a conductor transfer base material according to an embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view showing a shape of a through hole of a conductor transfer base material.

FIG. 3 is a partially enlarged cross-sectional view showing another shape of the through hole of the conductor transfer base material.

FIG. 4 is a schematic cross-sectional view showing the structure of a conductor having a multilayer structure.

FIG. 5 is a schematic cross-sectional view illustrating formation of a recess in a conductor transfer base material.

FIG. 6 is a schematic cross-sectional view showing the structure of a conductor transfer base material according to another embodiment of the present invention.

FIG. 7 is a schematic cross-sectional view showing the structure of a conductor transfer base material according to another embodiment of the present invention.

FIG. 8 is a schematic cross-sectional view showing the structure of a conductor transfer base material according to another embodiment of the present invention.

FIG. 9 is a schematic cross-sectional view showing a method for transferring a conductor according to an embodiment of the present invention.

FIG. 10 is a schematic cross-sectional view showing a method for transferring a conductor according to another embodiment of the present invention.

FIG. 11 is a schematic cross-sectional view illustrating a manufacturing process of the conductor transfer base material illustrated in FIG. 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating film 2 Conductor 2a Protrusion 8 Recess 9 Through hole K Conductor transfer substrate

Claims (9)

[Claims] 1. A conductor transfer in which a conductor having a protrusion protruding into the recess is detachably held in a through hole penetrating in the thickness direction of a recess for fitting a transfer target formed in an insulating film. Substrate. 2. The conductor transfer base material according to claim 1, wherein the through hole has a taper. 3. The conductor transfer substrate according to claim 1, wherein a support layer is formed on the surface of the insulating film opposite to the recessed surface. 4. The conductor transfer substrate according to claim 3, wherein the support layer is a metal layer. 5. The conductor transfer substrate according to claim 3, wherein the support layer comprises a thermoplastic insulating resin layer and a metal layer. 6. The conductor according to claim 4 or 5, wherein the metal layer is formed with minute through holes penetrating the metal layer in the thickness direction and communicating with an end face of the conductor and a joint surface between the metal layer. Transfer base material. 7. The conductor transfer substrate according to claim 1, wherein the conductor is a metal having a low melting point. 8. A transfer target is fitted into the recess of the conductor transfer base material according to claim 1, and is heated and / or pressurized to bring the conductor to a processing position of the transfer target. A method of transferring a conductor, comprising removing the insulating film of the base material after transferring. 9. The transfer target is fitted into the recess of the conductor transfer base according to claim 7, and then heated to melt and separate the metal having a low melting point from the base to a predetermined position of the transfer target. A method for transferring a conductor, which is characterized in that: