JPH10261736A - Wiring board with bump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board with bumps wherein bumps whose volumes or heights are uniform are arranged, effective manufacturing is possible and problems like short-circuiting is not generated owing to kinds of materials of the bumps, when the heights of the bumps are set to be considerably large. SOLUTION: A wiring board with bumps is provided with a board 103 and a plurality of bonding bumps which are formed by cutting line or pillar shaped long bump material 50 into pillar shaped objects having specified lengths in the longitudinal directions, mounting the pillar shaped objects on the connecting surface of the board 103 and bonding the pillar shaped objects to the connecting surface. Since, in the wiring board 103, bumps are formed by cutting the bump material 50 into specified lengths and mounting and bonding the cut material on the board, irregularity of volume and height of the bumps can be restrained within a small range by controlling the cutting length of the bump material 50, and manufacturing is effectively possible when the number of the bumps is large.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring having bumps, such as a flip-chip connection board for flip-chip connection of an integrated circuit chip and an electronic component mounting board for mounting electronic components and connecting them to a printed circuit board. Regarding the substrate.

[0002]

2. Description of the Related Art Conventionally, for example, when an integrated circuit chip is mounted on an integrated circuit board, a plurality of solder bumps are formed in a grid or staggered pattern on a connection surface between the integrated circuit chip and the integrated circuit board. There is known a connection method called a flip chip in which an integrated circuit chip is superimposed on a substrate and heated to a predetermined connection temperature to connect the two via solder bumps. In connection between an electronic component mounting board on which electronic components such as an integrated circuit chip are mounted and a printed circuit board (such as a motherboard), the other connection surface of the electronic component mounting substrate (the side opposite to the connection surface on which the electronic components are mounted) is connected. A connection method is also known in which a plurality of solder bumps are formed in a grid pattern using high-melting solder for connection or balls of Cu or the like on the connection surface, and a printed circuit board is overlaid on the bumps and heated in the same manner. Such a substrate is called a ball grid array (BGA) substrate.

As a method of forming solder bumps on a substrate as described above, a solder paste is printed at a predetermined position on a substrate via a screen mask (or a metal mask), and the solder paste is heated to form a solder paste. There is known a solder paste printing method in which bumps are formed on a substrate by melting the solder paste. In addition, as a material of the solder bump, generally, a solder having a eutectic composition or a composition close to the eutectic composition is used.However, when the substrates are joined to each other, crushing of the bump may be a problem. In some cases, a ball having a high melting point such as Ag or a high melting point solder (for example, Pb-5 wt% Sn alloy) is used as a central core in the bump. In the latter case, the bumps are manufactured by a method in which a eutectic solder paste is first placed on a substrate, a ball is further mounted on the substrate, and then the paste is melted by heating to integrate the paste with the ball.

[0004]

However, in the method of forming solder bumps by the solder paste printing method, the volume of the solder paste to be applied tends to vary. For example, when the volume is insufficient, the bonding of the substrate is difficult. In such a case, a shortage of the bump height may lead to a connection failure or the like, and conversely, if the volume is excessive, a short circuit may occur between adjacent bumps when connecting the substrate. On the other hand, Cu
When a bump with a high melting point ball such as Ag or Ag is used, the bump height is determined by the diameter of the ball, so that poor contact is unlikely to occur, but extra steps and equipment for mounting the ball are required. In addition to the above, there is a disadvantage that it is not possible to manufacture a small bump having a certain dimension or less due to difficulty in mounting the ball.

When the substrates are connected to each other by using bumps, as shown in FIG. 17, the upper substrate 301 and the lower substrate 302 are relatively moved in the plate surface direction due to a difference in thermal expansion during the connection process. May be displaced. In this case, both substrates 30
The bump 303 connecting the first and second 302 is deformed by receiving a shear stress in the direction of the displacement. At this time, when the height h of the bump 303 is small, as shown in FIG. 17A, there is a problem that the bump 303 is greatly sheared and deformed, and a trouble such as a crack is likely to occur. If the height h of the bump 303 is larger than a certain value, the shearing deformation of the bump itself can be suppressed to a small level as shown in FIG. Occurs.

First, when the bumps are made of eutectic solder, the bumps are almost completely melted during reflow, and the bump shape becomes spherical or hemispherical. In some cases, the diameter of the bumps becomes large, and insulation between adjacent bumps cannot be secured. On the other hand, when a ball having a high melting point is incorporated in the bump, the ball diameter must be increased in order to increase the bump height, and the same problem occurs. Therefore,
A method of forming a bump by growing the high melting point metal material in a columnar shape on a substrate by plating is also conceivable. However, when the height h of the bump is large, there is a problem that it takes a considerable time to grow the plating layer. . Particularly, in the case of a bump having a height of 200 to 300 μm or more used for a BGA substrate or the like, it is substantially impossible to form the bump by plating while securing mass productivity. Was never used.

SUMMARY OF THE INVENTION An object of the present invention is to provide a bump with uniform volume or height and to be able to efficiently manufacture the bump. It is another object of the present invention to provide a wiring board with bumps, which does not cause the above problems.

[0008]

Means for Solving the Problems and Functions / Effects In order to solve the above-mentioned problems, a wiring board with bumps (hereinafter, also simply referred to as a wiring board) of the present invention is composed of a substrate and a long line or column. A plurality of bumps formed by cutting the bump material into pillars of a predetermined length in the longitudinal direction, placing the pillars on the connection surface of the substrate, and connecting them to the connection surface. It is characterized by having. In the above wiring board, the bump material is cut into a predetermined length, and the bump is formed by mounting and joining the bump material to the substrate. Therefore, by controlling the cutting length of the bump material, variations in the volume or height of the bump can be reduced. It can be reduced to a small size, and can be manufactured efficiently even when the number of bumps to be formed is large. In addition, since the long bump material is easily available and inexpensive as compared with the ball-shaped or paste-shaped material, there is an advantage that the manufacturing cost of the wiring board can be reduced.

In the wiring board with bumps as described above, a step of cutting a linear or columnar long bump material into columns having a predetermined length in the longitudinal direction, and placing the columns on the connection surface of the substrate. It can be manufactured by a manufacturing method including a step and a step of joining the placed columnar object to the connection surface of the substrate. In this case, the height of the bump is determined according to the cutting length of the long bump material (that is, the height of the pillar). The bump volume is determined according to the axial cross-sectional diameter and height of the columnar object.

A base conductive pad (hereinafter, also simply referred to as a pad) can be formed in advance at a bump formation position on a substrate, and a columnar object is placed on this pad and joined thereto. Can form a bump.
Also, if a flux is applied to the entire surface of the substrate or at least on the pads on the connection surface, and then a columnar material obtained by cutting the long bump material is placed and joined, The applied flux improves the wettability between the column and the pad, and the placed column is temporarily fixed due to the viscosity of the flux, so that the displacement is less likely to occur, and the trouble such as poor connection is less likely to occur. .

Note that the wiring board referred to in this specification means not only a board on which an integrated circuit chip is mounted, but also a board connected to a printed board and the integrated circuit chip itself (that is, a flip chip). Specifically, a substrate provided with a plurality of bumps on one surface for connection to an integrated circuit chip (flip chip connection), and a substrate provided with a plurality of bumps for connection to a printed circuit board on one surface , Or an integrated circuit chip having a plurality of bumps. The plurality of bumps can be arranged linearly or in a plane. As a linear arrangement pattern, for example, there is an aspect in which the linear arrangement pattern is arranged in a rectangular frame shape. Examples of the planar arrangement pattern include, for example, an arrangement in a lattice or staggered arrangement.

In the above wiring board, the bumps can be formed in a columnar shape whose height is larger than the maximum diameter of the axial cross section. By making the height of the bump larger than the maximum diameter of its axial cross section, as shown in FIG. When connecting the substrates 301 and 302 (for example, the wiring substrate of the present invention is on the lower side and the connected object is on the upper side), the shear deformation of the bumps when they are relatively displaced in the plate surface direction due to a difference in thermal expansion or the like is reduced. Thus, troubles such as cracks in the bumps due to the deformation are less likely to occur. Also, a columnar bump having a large height, which has been difficult to manufacture by a conventional method such as plating, can be easily formed by cutting a long bump material.

The height of the bump can be set to, for example, 200 μm or more. Such a bump can be particularly suitably used for a substrate having a large inter-substrate distance, such as an integrated circuit package substrate connected to a printed substrate by a bump. The bumps used for such a substrate are
The height is desirably 300 μm or more.

The axial cross section of the bump can be formed in various shapes. For example, a circular shape, that is, the entire bump can be formed in a column shape. According to this, there is an advantage that a long material (for example, a wire) having a circular cross section which is easily available can be used as the bump material.

Specifically, the bump is formed by arranging a mold in which a plurality of material insertion holes are formed in a penetrating form so that a predetermined gap is formed above the substrate and the substrate. A long bump material is inserted into each material insertion hole of the mold so that the end of each material protrudes toward the substrate by a predetermined length. To form a columnar material, which is mounted on a substrate and joined to form a columnar material. This makes it possible to manufacture a large number of bumps very efficiently.

More specifically, bumps can be manufactured more efficiently by using the following apparatus. Lower die: A plurality of material insertion holes which are formed in a plate shape, have a corresponding shape of the bump material, and penetrate the same in the plate thickness direction, are provided in accordance with the number of bumps and the arrangement thereof. . Upper die: formed in a plate shape laminated on the lower die, arranged so as to be relatively movable in the plate surface direction with respect to the lower die, and formed with a plurality of material insertion holes corresponding to the material insertion holes of the lower die. Mold slide means: The lower mold and the upper mold are relatively slid in the plate surface direction. Substrate conveying means: intermittently conveys the substrate in the plate surface direction. Substrate positioning means: controlling the driving of the substrate transport means,
The substrate is positioned with respect to the lower die so that the bump placement position is aligned with the corresponding material insertion hole. Mold approach / separation means: The upper mold and the lower mold are relatively and integrally approached / separated from the substrate. Wire feeding means: With the lower material insertion hole and the upper material insertion hole aligned with each other, a long bump material is intermittently fed into the material insertion holes by a predetermined length.

Hereinafter, the material of the bump which can be employed in the present invention and the specific structure of the bump related thereto will be described. First, as a material for the bump, a material having a melting end temperature (or a liquidus temperature) lower than a reflow temperature (bonding temperature) for bump bonding can be used.
For example, when the joining temperature is about 230 ° C., it is also possible to use an Sn—Pb alloy having a composition close to the eutectic composition (so-called eutectic solder). In this case, when the columnar object is bonded to the substrate, it is almost completely melted, and the obtained bump shape is spherical or hemispherical. However, when the bumps are formed of such a material, the bumps are connected to the wiring board when another board or a connected body such as an integrated circuit chip is heated to a temperature substantially equal to the reflow temperature and connected. There is a case where a problem of crushing with the connected object occurs.
Then, as a mode for preventing such crushing of the bump, the following is possible.

(Aspect 1) A material whose melting start temperature is higher than the connection temperature between the wiring substrate and the object to be connected, for example, a metal or alloy whose melting start temperature is 230 ° C. or higher (for example, Au, Cu, A
g, Pb, Sn or an alloy mainly containing at least one of them) is used as the bump material. Specifically, a columnar object composed of the above bump material is placed on a substrate, and heated to a bonding processing temperature higher than a melting start temperature of the material, thereby joining this to the substrate to form a bump. I do. Since the bump is made of a material having a melting start temperature higher than the connection temperature between the wiring board and the connected body, the bump is prevented from being crushed by melting during the connection. In this case, since the joining temperature of the columnar material is high, it is necessary to use a material such as ceramic that does not deform or change at that temperature. Further, when connecting the connected object to the wiring board on which the bump is formed, since the bump itself does not melt, the connection position with the bump on the connected object side is at least partially melted at the connection temperature. It is necessary to form a brazing material layer (for example, a eutectic solder layer) by printing or the like. In this specification, the “melting start temperature” is a general term for a temperature at which melting of a metal or an alloy is started at an elevated temperature, such as a melting point, a solidus temperature, a eutectic temperature, and a peritectic temperature. .

(Aspect 2) A bump including a pillar-shaped bump body and a bonding layer formed of a brazing material having a lower melting start temperature than the constituent material of the bump body and bonding the bump body to a connection surface. The wiring board is configured to have the following. In this case, the bump is formed by cutting a linear or columnar bump material into a predetermined length in the longitudinal direction, and the columnar material to be the bump body is formed on the brazing material pattern formed on the connection surface of the substrate. And then melting the brazing material pattern to join the pillars to the connection surface.

Specifically, the bump body is made of a material whose melting start temperature is higher than the connection temperature between the wiring board and the object to be connected, for example, a metal or alloy whose melting start temperature is 230 ° C. or higher (for example, Au, Cu, Ag, Pb, Sn or an alloy containing at least one of them as a main component). Further, the brazing material pattern can be formed of a brazing material (for example, eutectic solder) that is at least partially melted at a joining temperature of the bump body to the substrate. As a method for forming a brazing material pattern, a method in which a preform made of the brazing material is placed on a substrate or a method in which a brazing material paste is applied by printing or the like can be used.
Also in this case, as in the first aspect, the bumps are made of a material having a melting start temperature higher than the connection temperature with the connected body, so that the bump is prevented from being crushed during the connection between the wiring board and the connected body. The Rukoto. Further, since the bump itself does not melt, it is necessary to form a brazing material layer (for example, a eutectic solder layer) which is at least partially melted at the connection temperature by printing or the like at a connection position with the bump on the connected body side. There is.

The bumps can be formed as follows. That is, a linear or columnar core material,
A composite columnar material obtained by cutting a composite long bump material composed of a brazing material having a melting start temperature lower than that of the core material and having a lower melting start temperature than the core material into a predetermined length in the longitudinal direction is formed on the connection surface of the substrate. Place and melt the brazing material. As a result, the core portion of the composite columnar material to be the bump body is joined to the connection surface by the molten brazing material portion to form the bump.

According to this structure, when the composite columnar material obtained by cutting the composite long bump material is heated to the joining temperature, the brazing material is melted, and the core material is connected to the substrate by the melted brazing material. It is joined to the surface to form a bump body. In this way, without forming a brazing material pattern, a bump can be obtained simply by cutting the long bump material, placing the material on the bonding surface of the substrate, and heating, so that the brazing material pattern forming step is unnecessary, The production efficiency of the wiring board with bumps can be improved. Further, since the amount of brazing material can be accurately controlled by the cutting length of the composite long bump material, there is an advantage that there is no excess or deficiency of brazing material at the time of joining and the joining strength can be kept constant.

More specifically, a core material made of a material (for example, a metal or an alloy as described above) whose melting start temperature is higher than the connection temperature between the wiring board and the object to be connected is prepared by:
A brazing material (for example, eutectic solder) that is at least partially melted at a joining temperature of the core material serving as the bump main body to the substrate and that is a brazing material disposed around the core material may be used. In addition, as a method for forming such a long bump material, a wire (eg, Cu wire or Pb
-Sn high-temperature solder, etc.), a method of plating a brazing material (for example, eutectic solder) having a lower melting start temperature, or cladding the two so that the brazing material is arranged around the core material. And the like. In this case, as in the first aspect, the bumps are formed of a material having a melting start temperature higher than the connection temperature with the connected body, so that the bump is prevented from being crushed during the connection between the wiring board and the connected body. Is done. Further, the bump body itself does not melt, but the brazing material melts, so that the connected object and the bump body can be connected with this brazing material. However, when the amount of the brazing material is small, a brazing material (for example, eutectic solder) that is at least partially melted at the connection temperature may be formed at the connection position on the connected body side by printing or the like.

(Embodiment 3) In the present system, a substrate is connected to another connection object such as an integrated circuit chip or the like on a connection surface thereof and a predetermined connection temperature (for example, 200 to 2)
By heating to 20 ° C.), the connected object is expected to be connected via the bump, and the bump is partially melted at the connection temperature to generate a liquid phase, and
The resulting liquid phase portion and the remaining solid phase portion are configured to form a mixed state with each other.

When the above-mentioned bump is used, the bump is partially melted at a connection temperature to form a liquid phase, and the liquid phase is supplied to a contact portion between the connected member and the bump, and then the liquid phase is cooled. As a result, the substrate and the connected body are connected via the bumps. Here, since the bump forms a state in which the liquid phase portion and the solid phase portion are mixed with each other at the connection temperature, there is no fear that a trouble such as a bump using eutectic solder that is completely melted or collapsed occurs. .

Such a bump forms a state in which a solid phase and a liquid phase coexist at a connection temperature (hereinafter, also referred to as a solid-liquid coexistence state), and has a solid phase abundance ratio of 20 to 95 weight at a connection temperature. % Alloy. That is, according to this configuration, the bumps that form a state in which the liquid phase portion and the solid phase portion are mixed with each other at the connection temperature can be easily manufactured using an alloy.

The following are conceivable factors that make it difficult for the above-mentioned bumps to be crushed during connection. For example, when the entire bump is in a liquid phase at the time of connection, the force for maintaining the bump shape is almost only surface tension, so that the bump is crushed by a slight external force. However, when the bumps are in a solid-liquid coexisting state (ie, in a semi-molten state) as in the bumps described above, frictional force is generated at the interface between the solid phase portion and the liquid phase portion when the bumps try to flow and deform. As a result, the apparent viscosity increases, and the shape maintaining force of the bump during connection is increased. In addition, the solid phase portions may be connected to each other to form, for example, a three-dimensional mesh-like skeleton structure. In this case, the deformation of the skeleton is required to deform the bumps. improves.

As a method of forming such a bump, after a bump material is cut into a columnar body, a temperature higher than a melting start temperature of the bump material and lower than a melting end temperature (for example, a liquidus temperature). By performing the bonding process in, a method of melting only a part of the columnar material to generate a liquid phase and bonding the columnar material to the substrate via the liquid phase can be exemplified. In this case, since the columnar material forms a solid-liquid coexistence state at the time of bonding to the substrate, it exhibits a certain shape retention property, and as a result, the bump shape at least partially maintains the columnar shape. When the bonding temperature is 230 ° C. or lower, bumps can be formed on a plastic substrate or the like.
On the other hand, the joining process of the columnar object can be performed at a temperature higher than the melting end temperature of the bump material. In this case, the bump shape becomes spherical or hemispherical because all of the bump shape is once melted. In addition, since the joining temperature of the columnar material becomes high, it is necessary to use a material such as ceramic which does not deform at the temperature, such as ceramic.

The alloy constituting the bumps has a solid phase content of 20% by weight at the connection temperature between the wiring board and the object to be connected.
If less than this, the fluidity of the bumps is increased and the crush prevention effect may not be sufficiently achieved. On the other hand, when a solid phase having an abundance of more than 95% by weight is used, an insufficient amount of a liquid phase may be generated, and a sufficient connection state may not be formed between the connected member and the bump. Therefore, it is preferable to use an alloy having a solid phase abundance of 20 to 95% by weight, and more preferably an alloy having a solid phase abundance of 40 to 70% by weight. .

The bump using the above-mentioned alloy is prepared by cutting a long bump material made of the alloy into a predetermined length by the above-described method to form a column, and mounting the column on a substrate. By heating above the melting start temperature of the alloy to partially melt this to generate a liquid phase, and by joining the columnar object to the substrate through the liquid phase,
A method for obtaining a bump can be employed. In this case, the bumps can be formed without using a brazing material or the like separately while substantially maintaining the columnar shape.

More specifically, the bump forms a state in which a solid phase and a liquid phase coexist at least in a temperature range of 200 to 220 ° C., and an abundance ratio of the solid phase in the temperature range is 20 to 220 ° C. It can be constituted by an alloy which becomes ９５95% by weight. That is, at least in the temperature range of 200 to 220 ° C., which has been widely used in connection processing of a conventional substrate having a eutectic solder-based bump, the bump of the wiring board has a solid phase abundance of at least 20 to 95% by weight. Is formed from an alloy that forms a solid-liquid coexistence state, when the connection process is performed in the temperature range, no trouble occurs such that the bumps are crushed, and the connection between the object and the connected object is good. Connection state can be formed. In other words, the connection processing can be performed using the connection temperature conditions of the substrate having the eutectic solder-based bumps as they are.

In the above structure, the bump can be made of an alloy containing one or more of Pb, Sn and Au as main components. For example, as such an alloy, an alloy containing at least one of Pb and Sn in a total amount of 80% by weight or more (for example, Pb-S
n solder alloy or Sn-Pb solder alloy) is a general-purpose material that is inexpensive and has excellent brazing properties, and can be suitably used for the bump of the wiring board of the present invention. In addition,
In an alloy which forms a solid-liquid coexistence state in which at least a solid phase abundance ratio is 20 to 95% by weight, desirably 40 to 70% by weight in a temperature range of 200 to 220 ° C, Pb
And / or an alloy having a total content of Sn of less than 80% by weight can be suitably used as a material of the bump of the present invention. In addition, except for the Pb-Sn alloy, Au
-Tl alloys and the like can also be used.

When the bump is made of an alloy containing, for example, both Pb and Sn in a total amount of 80% by weight or more, Pb
And the content ratio of Sn to the total amount of Sn and Sn is 20 to 40.
By setting the weight percent, the abundance ratio of the solid phase in the temperature range of 200 to 220 ° C. can be adjusted within the range of 20 to 95 weight%, and as described above, the bumps can be prevented from being crushed. A good connection state can be formed. If the Sn content ratio is less than 20% by weight, the solid phase abundance in the above temperature range exceeds 95% by weight, and if it exceeds 40% by weight, the solid phase abundance becomes less than 20% by weight. Connect. In order to adjust the abundance ratio of the solid phase to a more desirable range of 40 to 70% by weight, the Sn content ratio is preferably adjusted to a range of 28 to 33% by weight. Note that a more specific alloy composition is S
A Pb-Sn binary alloy having an n content of 20 to 40% by weight can be used.

Next, the bump has a structure in which a solid phase forming metal part and a liquid phase forming metal part having a lower melting start temperature than the solid phase forming metal part are mixed with each other. At the connection temperature with the above, at least a part of the liquid phase forming metal part is melted to form a liquid phase.

That is, in the wiring board having the above-described structure, the bumps have two portions having different melting start temperatures, namely, a solid-phase forming metal portion having a high melting start temperature and a liquid-phase forming metal portion having a low melting start temperature. At the connection temperature, the liquid-phase forming metal part is at least partially melted to generate a liquid phase, while the solid-phase forming metal part is at least partially maintained in a solid state, thereby forming a connection temperature. Since the liquid phase part and the solid phase part form a mixed state in each other, troubles such as crushing of bumps during connection are less likely to occur, and thus, a good connection state is formed with the connected body. Can be. The connection temperature can be set, for example, between the melting start temperature of the solid phase forming metal part and the melting start temperature of the liquid phase forming metal part.

Specifically, the bump has a large number of metal particles as solid-phase forming metal parts and a bonding metal part as a liquid-phase forming metal part that at least partially fills a gap between the metal particles. It can be composed of a composite material. According to the above configuration, since the bumps are formed by the composite material in which a large number of metal particles are dispersed in the bonding metal portion, there is an advantage that the combination of the materials of the bonding metal portion and the metal particles can be selected relatively freely. In addition, since a composite material in which metal particles and a bonding metal part are mixed and dispersed in advance is prepared and a bump may be formed using the composite material, for example, a conventional ball-mounted bump such as a built-in ball type bump may be used. The process and equipment are not required, so that the manufacturing cost can be reduced and small-sized bumps can be easily manufactured.

In the above configuration, the content of the metal particles is determined at least by the connection temperature between the wiring board and the object.
For example, in the temperature range of 200 to 220 ° C., the proportion of the solid phase is 20 to 95% by weight, preferably 40 to 70% by weight.
It is adjusted so that Sn content ratio is 20% by weight
If it is less than 9, the solid phase abundance ratio in the above temperature range becomes 9
If it exceeds 5% by weight, and if it exceeds 40% by weight, the abundance of the solid phase will be less than 20% by weight. In this case, when most of the bonding metal part is in a liquid phase at the connection temperature, the content of the metal particles in the composite material may be adjusted in the range of 20 to 95% by weight, preferably 40 to 70% by weight. .

The bump using the composite material as described above is
Using a composite material in which metal particles are dispersed in a bonding metal part as a bump material, for example, mixing a metal powder and a metal particle to be a bonding metal part, and then baking or extruding the mixture, using an appropriate method. It can be formed by molding into a linear or columnar long form, cutting the columnar body, and mounting and joining the substrate on a substrate.

When bumps are formed using the above-described composite material, in order to increase the shape maintaining force during the connection process, an appropriate amount of liquid is generated between the liquid phase generated by the melting of the bonding metal portion and the metal particles. It can be said that it is desirable to select a material having good wettability with respect to the bonding metal portion as the metal particles so that a high frictional force acts and the metal particles are uniformly dispersed in the bonding metal portion.

In the bump, an alloy layer containing a part of a component of a bonding metal part and a part of a component of a metal particle is formed along the surface of the metal particle, and the metal particle is interposed through the alloy layer. They can be configured as having a structure in which they are connected to each other. Thus, the metal particles (that is, the solid phase portions) are connected to each other via the alloy layer to form, for example, a three-dimensional network skeleton structure, and the shape retention force of the bump during the connection process is further increased. Such an alloy layer
For example, of the liquid phase generated by melting of the binding metal part, components of the metal particles are eluted in a portion located near the interface with the metal particles, and the melting start temperature (solidus temperature) increases, and Formed based on the solidification of the liquid phase.

The bonding metal portion is desirably made of a material capable of rapidly melting at the connection temperature to generate a sufficient amount of liquid phase, and more specifically, an alloy containing 50 to 80% by weight of Sn. be able to. In this case, the remainder of the bonding metal portion excluding the Sn component can be mainly composed of Pb, and more specifically, Sn having a eutectic composition.
-Pb binary alloy (Sn-38.1 wt% Pb: so-called eutectic solder) or Sn-Pb binary alloy having a composition close thereto (for example, Pb content is 20 to 50 wt%) can be used. . The metal particles are made of a material having good wettability with a liquid phase based on such a bonded metal part, for example, at least one of Pb, Cu and Ag.
One or two or more metal particles mainly composed of one metal can be used. For example, in the case of particles of a metal mainly composed of Pb, Pb metal particles or particles of a Pb-Sn binary alloy (so-called high melting point solder) having a Pb content of 90% by weight or more can be used. Cu or Cu alloy particles can be used as the metal particles mainly composed of. Further, particles of an alloy containing two or more of Pb, Cu and Ag can be used.
Particles of a g-Cu alloy can be used. The metal particles may be all composed of the same material, or may be a mixture of two or more different materials.

The present invention also provides a wiring board with bumps having a substrate and a plurality of bumps arranged on a connection surface of the substrate and formed in a columnar shape having a height of 200 μm. In addition, a plurality of substrates and a plurality of connection surfaces are arranged on the connection surface of the substrate, each of which is formed of a columnar bump body and a brazing material having a lower melting point than the constituent material of the bump body. And a bump having a connection layer to be joined. In the configuration of these wiring boards, bumps formed by any of the various methods described above can be used. However, if the productivity for forming bumps is not extremely reduced, other bumps may be used. May be done.

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) In this embodiment, a wiring board with bumps for connecting integrated circuit chips by a flip chip method will be described as an example. As shown in FIG. 1A, a wiring board 3 with bumps (hereinafter also simply referred to as a wiring board) 3 has a large number of bumps 1 on a plastic substrate 103 of, for example, about 25 mm square and about 1 mm thick, for example, a grid. It has a structure fixed in a shape, and as shown in FIG.
An insulating layer 7 made of epoxy resin is formed on the BT core substrate 5, and a Cu internal wiring 9 is formed on the surface of the insulating layer 7 and between the BT core substrate 5 and the insulating layer 7.
In addition, as a method of forming the Cu internal wiring 9, a subtractive method or a full additive method can be used in addition to a semi-additive method using electroless Cu plating and electrolytic Cu plating.

On the outermost surface of the wiring board, a Cu wiring 1
For example, an electroless Ni—P plating layer 13 of about 3 μm having a diameter of about 1 mm is formed to prevent corrosion and improve adhesion to the bump 1. The bump 1 is fixed on the pad 17. The Ni-P plating layer 1
Although an electroless Au plating layer may be formed on 3, it is eroded in the bump 1 and disappears. In other parts, a solder resist layer 19 is formed of an acrylic resin, an epoxy resin, or the like.

The bump 1 is made of, for example, Sn having a eutectic composition.
-Pb binary alloy (Sn-38.1 wt% Pb: hereinafter referred to as eutectic solder) is used. Now, the bump 1 made of an alloy of the above-described material can be formed on the pad 17 (FIG. 1), for example, as follows. First, an alloy wire rod having a diameter of 1 mm (for example, DG-wire solder W-1.0, manufactured by Nihon Solder Co., Ltd., diameter: 1 ± 0.05 mm) is prepared, and cut into a predetermined length to form a columnar alloy preform. (Pillar) is prepared, and the preform is placed on the pad 17. The production of the preform and the mounting on the pad 17 can be efficiently performed by using, for example, the apparatus 49 shown in FIG.

The device 49 has the following requirements. Lower die 51: a plurality of wire insertion holes (material insertion holes) formed in a plate shape, having an inner diameter corresponding to the outer diameter of alloy wire 50 as a bump material, and penetrating this in the thickness direction.
A hole 52 is formed corresponding to the position of each pad 17 on the substrate 103. Upper die 53: formed in a plate shape laminated on the lower die 51, disposed so as to be relatively movable in the plate surface direction with respect to the lower die 51, and inserted a plurality of wire rods corresponding to the respective wire insertion holes 52 of the lower die 51. A hole (material insertion hole) 54 is formed. Mold sliding means: The lower mold 51 and the upper mold 53 are relatively slid in the plate surface direction. In this embodiment, the lower mold 51 is fixed to the frame 55, while the upper mold 53 is connected to the frame 55 via the cylinder 56 and the piston rod 57 as the mold sliding means. As a result, the upper mold 53 slides with respect to the lower mold 51.

Substrate transport means: For example, it is constituted by a conveyor 58 that can be driven and stopped intermittently, and transports the substrate 103. Substrate positioning means: controlling the driving of the conveyor 58,
The substrate 103 on the conveyor 58 is positioned with respect to the lower mold 51 such that each pad 17 is aligned with the corresponding wire insertion hole 52. Mold approach / separation means: The upper mold 53 and the lower mold 51 approach and separate from the substrate 103 on the conveyor 58 relatively and integrally. In the present embodiment, it is constituted by a cylinder 59 that raises and lowers the frame 55. Wire feeding means: wire insertion hole 52 of lower die 51 and upper die 53
The alloy wire 50 is intermittently fed into the wire insertion holes 52 and 54 by a predetermined length (1 ± 0.05 mm in this embodiment) in a state where the wire insertion holes 54 are aligned with each other. In this embodiment, a feed roll 60 that rotates while sandwiching the alloy wire 50 and a motor 61 that drives the feed roll 60 are provided. A wire storage portion (not shown) is provided above the lower mold 51 and the upper mold 53, and the alloy wire 50 is stored in a state wound around a reel or the like. This is intermittently fed out.

Hereinafter, a method of forming a bump using the device 49 will be described with reference to FIGS. That is,
As shown in FIG. 3A, the flux 65 is placed at a position corresponding to the pad 17 of the substrate 103 (or the entire surface of the substrate 103).
(In the case of full-surface application, for example, a roll coater can be used). The flux 65 is
Any of the R type, RMA type and RA type may be used. Next, as shown in FIG. 3B, the wire insertion holes 52 of the lower mold 51 and the wire insertion holes 54 of the upper mold 53 are aligned with each other. Positioning is performed so as to be located immediately below the wire insertion hole 52, and each wire insertion hole 52, 54.
The alloy wire 50 is inserted and supplied to the wire. Here, the alloy wire 5 is inserted into the wire insertion holes 52 and 54 of the upper mold 53 and the lower mold 51.
In order to supply 0 smoothly, the alloy wire 50 must be
It is preferable to make a clearance fit state at 2, 54. Specifically, the outer diameter of the alloy wire 50 is set to 1 ± 0.05 mm.
When the inside diameter of the wire insertion holes 52 and 54 is set to 1.06
It is good to set in the range of １．１1.10.

When the upper die 53 is slid with respect to the lower die 51 in this state, the alloy wire 50 is sheared between the two dies 51 and 53 in the axial sectional direction as shown in FIG. As a result, the preforms 66 are cut into cylindrical preforms 66 and placed on the corresponding pads 17. Next, as shown in FIG. 4A, the upper mold 53 and the lower mold 51 are retracted upward from the substrate 103 in the figure, and furthermore, the conveyor 58
By operating (FIG. 2), the substrate 103 on which the preform 66 is placed is discharged, the next substrate 103 is positioned with respect to the lower mold 51, and the upper mold 53 is brought into the state shown in FIG. To return to. Then, the alloy wire 50 is fed again by a predetermined cutting length, and the same steps are repeated thereafter.

The substrate 103 on which the preform 66 is mounted in this way is heated in a temperature range of 200 to 220 ° C. in a far-infrared ray reflow furnace, for example, and is subjected to a reflow treatment, as shown in FIG. As shown, the preform 66 is melted and joined to the pads 17 of the substrate 103 to form the spherical or hemispherical bumps 1. When the reflow treatment is performed in a non-oxidizing atmosphere (for example, nitrogen or hydrogen), the oxidation of the alloy or the pad 17 is prevented or suppressed, so that the bonding property can be improved. When the bonding is completed in this way, the flux applied to the substrate 103 is removed by washing with an organic solvent such as alcohol, for example, thereby completing the wiring substrate 3 on which the bumps 1 are formed. If a water-soluble flux is used, it can be removed by washing with water.

As shown in FIG. 5, a feed roll 60 for feeding out a plurality of adjacent alloy wires 50 may be formed coaxially and integrally. In this case, the alloy wire 50
The variation in the feed amount between the bumps 1 can be reduced, and the height and volume of the obtained bumps 1 can be made more uniform. Further, the wire feeding means is not limited to the configuration in which the alloy wire 50 is fed out using the feed roll 60. For example, as shown in FIG. 6, a reel 70 for holding each alloy wire 50 in a wound state is placed in a case 71. The wire rod 50 from each reel 70 is suspended from the bottom side of the case 71, and the case 71 is intermittently lowered by the elevating mechanism 73 in association with the cutting length while accommodating the wire rod storage section 72. Accordingly, it is also possible to adopt a configuration in which all the wires 50 are supplied integrally to the upper mold 53 and the lower mold 51.

In the above steps, the bump 1 is made of the alloy wire 5
0 is 1 ± 0.05mm and the feed length is 1.5 ±
By setting it to 0.05 mm, in other words, the preform 66 has a diameter of 1 ± 0.05 mm and a height of 1.5 ± 0.05 mm.
, The solder volume range is 1.03
It is formed so as to be 1.34 mm ³ . The bump shape has a diameter of 1.29 to 1.40 mm and a height of 1.05 to 1.
A bump having a substantially spherical shape of 19 mm and a small variation in height can be obtained.

The bump 1 is made of, for example, a material having a higher melting start temperature, for example, a content of Pb metal or Pb of 9%.
It is also possible to use a solder made of a Pb-Sn binary alloy of 0% by weight or more (so-called high melting point solder). In this case, since the reflow temperature for melting the preform 66 to form the bumps needs to be set at a high temperature of, for example, 300 to 350 ° C., the substrate 103 does not soften or deform at the reflow temperature such as ceramics. It must be made of material.

(Embodiment 2) As shown in FIG. 8B, a bump 1 is composed of a columnar bump body 80 and a bump body 8.
The bump body 80 may be formed of a brazing material having a lower melting start temperature than the constituent material of No. 0 and a brazing material layer 82 for joining the bump body 80 to the pad 17.
The bump body 80 is made of a material whose melting start temperature is higher than the connection temperature between the wiring board and the connected body, for example, the melting start temperature is 23.
Metal or alloy at 0 ° C. or higher, specifically, Au, Cu, A
g, Pb, Sn or an alloy containing at least one of them as a main component is formed in a columnar shape, and the height h is larger than the shaft cross-sectional diameter d. Also,
The brazing material layer 82 can be formed of a brazing material that at least partially melts at a bonding temperature of the bump body 80 to the pad 17. In this embodiment, the bump body 80 is made of Cu.
Therefore, the brazing material layer 82 is made of eutectic solder.

In this case, the bump 1 can be manufactured as follows using the device 49 of FIG. First, as shown in FIG. 7A, a paste containing eutectic solder particles and flux is applied to the substrate
A paste pattern (a brazing material pattern) 81 is formed by selectively applying only to the position corresponding to each pad 17 so that a short circuit does not occur between the pads 7. In addition, as a coating method, a known method such as a screen printing method or a dispenser printing method can be adopted. The eutectic solder particles and the flux in the paste are preferably mixed, for example, so that the content of the eutectic solder particles is about 50% by volume and the balance is flux.

Next, as in the first embodiment, FIGS.
As shown in FIG. 8D and FIG. 8A, the material wire (in this example, Cu wire φ1.0 mm) 50 of the bump body 80 is cut into a predetermined length (1.5 mm), so that the columnar bump is formed. The main body 80 is placed on the paste pattern 81 on each pad 17. At this time, the solder paste also plays a role of temporarily fixing the bump body 80 on the pad 17 due to its viscosity.
Next, this is subjected to a reflow treatment at a joining temperature of 200 to 220 ° C., so that the eutectic solder particles in the paste pattern 81 are melted to form a brazing material layer 82 as shown in FIG. Bump 1 joined to 17
Becomes The remaining flux is removed by washing. In this way, the bump 1 (the bump body 80)
Is made of Cu having a high melting start temperature, and when the connection processing of the connected body is performed at, for example, about 230 ° C., the bump body 80 is not melted at all, and the collapse of the bump body 80 is prevented. The bump 1 has a height h (= 1.5 m).
m) has a shape larger than the shaft cross-sectional diameter d (= 1.0 mm), so that shearing deformation due to thermal influence during connection can be suppressed small (see FIG. 17). Short-circuiting with the bump is unlikely to occur. The bump height is determined by the cutting accuracy of the material wire (1.5 ± 0.0 in this example).
5 mm), and the height variation can be made smaller than in the first embodiment. Therefore, the connectivity with the connected object is improved.

Instead of forming the brazing material layer 82 by applying the paste pattern 81, the following method can be adopted. That is, FIG.
A brazing material coating layer 82 'made of eutectic solder having a thickness of, for example, 0.05 mm formed by plating or the like so as to cover the periphery of a Cu wire (core material: φ1.0 mm) 80' as shown in FIG. A coated wire 200 (composite long bump material) is prepared. Next, as shown in FIG.
Is cut into a predetermined length using the same apparatus as described above to obtain a brazing filler metal-coated columnar member 1 ′ (composite columnar member).
Place on top. Then, as shown in FIG. 3C, when the solder is reflowed, the brazing material coating layer 82 'is melted, and the bump body 80 based on the Cu wire 80' is joined to the pad 17 by the brazing material layer 82 based on the reflow. Can be. This eliminates the need to apply the paste pattern 81 shown in FIG.

According to the present embodiment, the height h of the bump
Can easily be increased (in this example, h = 1.
5 mm). For example, bumps having a height of 300 μm or more, which cannot be industrially manufactured by a technique such as plating, can be easily manufactured.

(Embodiment 3) Wiring board 3 shown in FIG.
Is an alloy that forms a solid-liquid coexistence state in which at least a solid phase abundance ratio is 20 to 95% by weight, preferably 40 to 70% by weight in a temperature range of 200 to 220 ° C., such as Pb and Sn. Are contained in a total of 80% by weight or more, and the content of Sn relative to the total amount of Pb and Sn is 20 to 40% by weight, preferably 28 to 33% by weight. It has a shape whose height is larger than the shaft cross-sectional diameter. Hereinafter, Pb-Sn
The case where a binary solder alloy is used is taken as an example.

The behavior of the phase change and the structure change accompanying heating or cooling of the Pb—Sn binary alloy is shown in FIG.
It can be estimated based on the b-Sn system equilibrium diagram. The Pb-Sn system shows a typical eutectic phase diagram in which solid solubility limits are formed on both sides of Pb and Sn, and an α-solid solution (Pb side) at the eutectic temperature (about 183 ° C). Hereinafter, the solid solubility limit of Sn with respect to the α phase is 19.5% by weight, and the solid solubility limit of Pb with respect to the β-solid solution on the Sn side (hereinafter also referred to as the β phase) is 2.5% by weight, and the eutectic. The composition is 38.1% by weight Pb. To give an example, Pb-
When a binary alloy of 40% by weight Sn is used, if Pb and Sn are blended to have the above composition and heated and melted, both components are completely dissolved to form a single liquid phase L. Configure. Then, when this is cooled, as shown in FIG. 11A, the liquid phase L at the temperature A2 crossing the liquidus line L1 on the Pb side.
The primary crystals of the α phase begin to crystallize out. In the state diagram,
A portion surrounded by the liquidus line L1, the solid phase line Q1 on the Pb side, and the eutectic line E is a solid-liquid coexistence region of the α phase and the liquid phase L.

As shown in FIG. 11B, as the cooling proceeds, the ratio of the α phase increases due to the crystallization of a new α phase or the growth of the already crystallized α phase. Here, the existence ratio of the α phase and the liquid phase (residual liquid) equilibrated with the α phase at each temperature is represented by the so-called balance law (le
ver rule) can be calculated geometrically. For example, if the composition is Pb-40 wt% Sn and the temperature is 210
In the case of ℃, draw a straight line H parallel to the composition axis through the point of 210 ° C. on the temperature axis in the phase diagram, the intersection with the solidus Q1 is A3, and the intersection with the liquidus L1 is A4. And A straight line V parallel to the temperature axis is drawn through a point representing the composition of Pb-40% by weight Sn on the composition axis, and the intersection with the straight line H is defined as A5. In this case, assuming that the length of the line segment A3A5 is l1 and the length of the line segment A5A4 is l2, the existence ratio of the liquid phase L is {l1} (l1
+ L2)｝ × 100 (% by weight), and the abundance ratio of the solid phase (α phase) is {l2 ÷ (l1 + l2)} × 100 (% by weight). The composition of the liquid phase L and the composition of the α phase change along the liquidus line L1 and the solidus line Q1, respectively, as the temperature decreases.

Then, as shown in FIG. 11 (c), when the temperature further decreases and the α-phase grows, the α-phase particles initially floating independently in the liquid phase L are fused together. Thus, a skeletal structure connected in a three-dimensional network is formed, and the liquid phase L is held in the voids of the skeleton S. When the temperature reaches the eutectic temperature, the α phase and the β phase are simultaneously crystallized from the remaining liquid phase L by a eutectic reaction, and solidification is completed. As shown in the phase diagram of FIG. 10, the solid solubility limit of Sn in the α phase at the eutectic temperature is as large as 19.5% by weight, but the solid solubility limit near room temperature is very small. Therefore, when the solidified alloy is left at a temperature lower than the eutectic temperature, for example, at room temperature, the Sn component which cannot be dissolved completely precipitates in the α phase in the form of β phase. Here, FIG. 10 shows the amount of the primary α phase crystallized up to the eutectic temperature, the total amount of the α phase and the β phase to be eutectic solidified, and the α phase and the β phase in the eutectic. The amounts are shown together with the results calculated according to the balance law (all values at the eutectic temperature). On the other hand, when the content of Sn is 20 near the lower limit value.
In the case of the weight%, as is apparent from the phase diagram of FIG. 10, most of the liquid phase L solidifies as the α phase by the eutectic temperature. In this case, the β phase mainly consists of those precipitated in the α phase at a temperature lower than the eutectic temperature.

The bump 1 made of an alloy of the above-described material can be formed basically in the same manner as in the first embodiment. That is, as shown in FIG. 9A, a columnar preform 66 obtained by cutting an alloy wire is placed on a substrate 103 coated with a flux (not shown).
This is heated in a temperature range of 200 to 220 ° C. to perform a reflow treatment. As a result, the preform 66 is
The bump 1 is joined to the pad 17 of No. 03, and this is schematically shown in FIG. The bonding mechanism is presumed to be as follows. First,
Although the shape of the crystal grains of the preform 66 before the heating is changed by the drawing process, it is considered that the preform 66 has a texture state as shown in FIG. 11D. When the temperature becomes higher than the eutectic temperature, the β phase and the α phase in the alloy react to start melting. This melting reaction is presumed to proceed mainly between the eutectic β phase and the α phase that have finally solidified, but between the primary α phase and the β phase located close to this phase, or The reaction can proceed even between the β phase precipitated in the α phase at a temperature lower than the eutectic temperature and the surrounding α phase. The temperature of the alloy is substantially constant until the β phase is completely melted and disappears.

When the β phase is completely melted, the temperature starts to rise again, and the solid-liquid coexistence region (α +
Enter L). Thereafter, as the temperature increases, the melting of the remaining α phase progresses, and the ratio of the liquid phase L increases. Here, as shown in FIG. 11 (c), the skeletal structure of the α-phase once formed during the solidification gradually decreases in thickness from the surface layer as shown by the broken line in the figure with the rise in temperature. Α phase disperses in the liquid phase L
Rather than returning to the state shown in the floating figure (b), even if the thickness of the skeleton is reduced, the division does not easily occur, and the three-dimensional network structure is maintained at a relatively high temperature. Conceivable.

Then, a part of the generated liquid phase L exudes from the preform 66 while being held in the gap of the skeleton, and as shown in FIG. Supplied to the department. At this time, the abundance ratio of the solid phase (α phase) in the preform 66 at the central temperature of 210 ° C. in the above-mentioned temperature range is shown by the phase diagram shown in FIG. Degree, 30% by weight Sn 57% by weight, 40% by weight Sn 2
It is about 6% by weight. Then, if the liquid phase L is solidified by maintaining the state for a predetermined time and then cooling, the preform 66 is bonded to the substrate 103 as shown in FIG.

The wiring board 103 is formed, for example, as shown in FIG.
As shown in (a), the integrated circuit chip C is superimposed on the side on which the bumps 1 are formed, and is heated to a connection temperature of 200 to 220 ° C., whereby the bumps 1 are again in a solid-liquid coexistence state. The connection with the chip C is performed by the generated liquid phase L (FIGS. 12B and 12C). Here, unlike the conventional bump using the eutectic solder, all of the bumps 1 do not become the liquid phase L but leave the solid phase S even at the connection temperature 20 to 40 ° C. higher than the eutectic temperature. As shown in FIG. 11 (c), the solid phase (α phase) maintains the skeletal structure.
The shape maintaining force is increased, so that troubles such as being crushed between the integrated circuit chip (connected object) C and the substrate 103 during connection hardly occur.

On the other hand, the bump 1 has a structure in which a solid phase forming metal part and a liquid phase forming metal part having a lower melting start temperature than the solid phase forming metal part are mixed with each other.
At least a part of the liquid phase forming metal portion can be configured to melt to form a liquid phase. Specifically, as shown in FIG. 13, a composite having a large number of metal particles 201 as solid-phase forming metal parts and a binding metal part 203 as a liquid-phase forming metal part filling gaps between the metal particles. It can be constituted by the material 204.

The bonding metal part 203 is made of a material which can be quickly melted at a connection temperature, that is, 200 to 220 ° C. to generate a sufficient amount of liquid phase.
Alloy containing 80% by weight, more specifically, a Sn-Pb binary alloy having a eutectic composition (Sn-38.1% by weight P
b: hereinafter referred to as eutectic solder). on the other hand,
As the metal particles, those made of a material having good wettability with eutectic solder forming the bonding metal part 203, for example, Pb,
One or more metal particles mainly composed of at least one of Cu and Ag are used. In this embodiment, Pb metal or S
particles of a Pb-Sn binary alloy having a content ratio of n of 10% by weight or less (hereinafter, both are collectively referred to as a high melting point solder),
Alternatively, it is assumed that Cu particles are used, but Ag-C
Particles of a u alloy (for example, an Ag-Cu eutectic alloy) can also be used.

Next, an alloy layer 202 containing a part of the component of the bonding metal part 203 and a part of the component of the metal particle 201 is formed on the surface of the metal particle 201 along the surface thereof. The metal particles 201 are bonded to each other via the alloy layer 202 to form, for example, a three-dimensional network skeleton structure. For example, when the bonding metal part 203 is formed of eutectic solder and the metal particles 201 are formed of high melting point solder, the alloy layer 202 has a Pb- It becomes a Sn alloy. On the other hand, when the metal particles 201 are made of Cu, Pb and Cu hardly form a solid solution, so that the alloy is mainly composed of Cu and Sn.

The content of the metal particles 201 is 200
In the temperature range of ~ 220 ° C, the abundance ratio of the solid phase is 20 ~
It is adjusted to be 95% by weight, preferably 40 to 70% by weight. In this case, since the bonding metal part 203 is made of eutectic solder, almost the entirety becomes a liquid phase in a temperature range of 200 to 220 ° C., so that it is estimated that the total volume of the alloy layer 202 is not so large. In this case, the content of the metal particles 201 is preferably adjusted within the range of 20 to 95% by weight, preferably 40 to 70% by weight.

For the bump 1 as described above, for example, metal particles and a metal powder for forming a bonding metal part are mixed at a predetermined ratio, and the mixture is molded and then sintered, or is subjected to warm extrusion molding. In this way, a bloom or billet of a composite material is produced, and if this is rolled or drawn to form a wire, it can be formed in the same manner as in the first embodiment.

Here, when the metal particles 201 are made of a high melting point solder, as shown in FIG. 14A, the liquid phase L formed by melting the eutectic solder and the high temperature mainly composed of Pb are used. Since the Sn concentration is higher in the former and the Pb concentration is higher in the latter between the metal particles 201 formed of the melting point solder, Pb diffuses from the metal particles 201 side to the liquid phase L side, and the liquid phase L side From the metal particles 201 to the metal particles 201 side,
As shown in FIG. 3B, S around the metal particles 201.
A liquid phase portion L ′ in which the content of n is shifted to the Pb side from the eutectic composition, in other words, the Pb concentration is increased, is generated. When the Pb concentration increases, the liquidus temperature increases as is apparent from the state diagram of FIG. 10, and as shown in FIG. 10C, when the Pb concentration exceeds a certain level, it solidifies. To form an alloy layer 202 through which metal particles 201
These are joined to each other to form a skeletal structure. When the metal particles 201 are composed of Cu, the Cu component is eluted from the metal particles 201 to the liquid phase L side, and the Cu component reacts with the Sn component in the liquid phase to form Cu.
The -Sn-based alloy layer 202 is formed.

Wiring board 3 having bump 1 as described above
For example, as shown in FIG. 15A, an integrated circuit chip C is overlaid on the side on which the bumps 1 are formed and heated to a connection temperature of 200 to 220 ° C. As shown in FIG.
Is melted again to form a liquid phase L, and the liquid phase L is connected to the chip C by the generated liquid phase L, as shown in FIG. Here, the bump 1 is 200 to 2
Even at 20 ° C., not all of them are in the liquid phase L, and the metal particles 201 remain as a solid phase, and are bonded via the alloy layer 202 to maintain the skeleton structure. And the trouble of crushing between the integrated circuit chip (substrate) C and the substrate 103 during connection is less likely to occur.

[Brief description of the drawings]

FIG. 1 is a perspective view and a sectional view schematically showing an example of a wiring board with bumps according to a first embodiment of the present invention.

FIG. 2 is a diagram conceptually showing a main part of an apparatus for producing a preform and mounting the preform on a substrate.

FIG. 3 is an explanatory view of a manufacturing process of a wiring board with bumps using the apparatus of FIG. 2;

FIG. 4 is a process explanatory view following FIG. 3;

FIG. 5 is a schematic view showing a modified example of a feed roll in the apparatus of FIG. 2;

FIG. 6 is a schematic view showing another example of the configuration of the wire feed means.

FIG. 7 is a view illustrating a manufacturing process of the wiring board with bumps according to the second embodiment.

FIG. 8 is a process explanatory view following FIG. 7;

FIG. 9 is a view illustrating a manufacturing process of the wiring board with bumps according to the third embodiment.

FIG. 10 is a Pb-Sn binary system equilibrium diagram.

FIG. 11 is an explanatory view showing a solidification process of an alloy used for a bump of a wiring board according to a third embodiment.

FIG. 12 is an explanatory view showing a step of connecting an integrated circuit chip to the wiring board according to the third embodiment.

FIG. 13 is a schematic diagram showing a structure of a composite material used for a bump of a wiring board according to a third embodiment.

FIG. 14 is an explanatory view showing a process of forming the alloy layer.

FIG. 15 is an explanatory view showing a step of connecting an integrated circuit chip to a wiring board of Embodiment 3 having bumps made of a composite material.

FIG. 16 is an explanatory view showing a modification of the manufacturing process of the wiring board with bumps according to the second embodiment.

FIG. 17 is an explanatory diagram showing a state in which the amount of deformation of the bump changes according to the height of the bump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bump 3 Wiring board 50 Alloy wire (Long bump material) 51, 53 Die 52, 54 Wire insertion hole (Material insertion hole) 66 Preform (Columnar *) 80 Bump main body 80'Cu wire (Core material) 81 Paste pattern 82 brazing material layer 82 'brazing material coating layer (brazing material) 103 substrate L liquid phase S solid phase 201 metal particles 202 alloy layer 203 bonding metal part

Claims (13)

[Claims] 1. A substrate and a columnar object obtained by cutting a linear or columnar long bump material into a predetermined length in the longitudinal direction are placed on a connection surface of the substrate, and joined to the connection surface. A wiring board with bumps, comprising: a plurality of bumps formed by: 2. The wiring board with bumps according to claim 1, wherein the bumps have a columnar shape whose height h is larger than a maximum diameter d of an axial cross section. 3. The wiring board with bumps according to claim 1, wherein the bumps are formed in a columnar shape. 4. The wiring board with bumps according to claim 1, wherein the bumps are formed in a column shape having a height of 200 μm or more. 5. A mold in which a plurality of material insertion holes are formed in a penetrating form, respectively, is disposed above the substrate so that a predetermined gap is formed between the mold and the substrate. The long bump material is inserted into the material insertion hole such that each end thereof projects a predetermined length toward the substrate side,
Next, the protruding portion of the long bump material from the mold is cut by a predetermined cutting means to form the columnar object, and the bump is formed by mounting and joining the same on the substrate. 5. The wiring board with bumps according to any one of 1 to 4. 6. The bump includes a pillar-shaped bump main body and a bonding layer formed of a brazing material having a lower melting start temperature than a constituent material of the bump main body, and joining the bump main body to the connection surface. Claims 1 to 5
The wiring board with bumps according to any one of the above. 7. The method according to claim 1, wherein the bump is formed by cutting a linear or columnar long bump material into a predetermined length in a longitudinal direction thereof.
7. The bump according to claim 6, wherein the bump is formed by placing the pillar on the connection surface by placing the solder on the brazing material pattern formed on the connection surface of the substrate and then melting the brazing material pattern. With wiring board. 8. The method according to claim 1, wherein the bump comprises a linear or columnar core material, and a brazing material disposed around the core material and having a lower melting start temperature than the core material. The composite columnar material obtained by cutting to a predetermined length in the direction is placed on the connection surface of the substrate, and the brazing material portion is melted, whereby the core material portion of the composite columnar material to be the bump main body is formed. 7. The wiring board with bumps according to claim 6, wherein the wiring board is formed by being joined to the connection surface by the molten brazing material portion. 9. The board is connected to another connection body such as an integrated circuit chip or the like on the connection surface and heated to a predetermined connection temperature, so that the board is connected to the connection body via the bump. The bumps are partially melted at the connection temperature to form a liquid phase, and the resulting liquid phase portion and the remaining solid phase portion are mixed with each other. The wiring board with bumps according to any one of claims 1 to 5, wherein the wiring board is configured as: 10. The bump according to claim 1, wherein said bump has a thickness of at least 200-2.
A solid phase and a liquid phase coexist in a temperature range of 20 ° C., and the abundance ratio of the solid phase in the temperature range is 20 to
10. The wiring board with bumps according to claim 9, wherein the wiring board is made of an alloy that accounts for 95% by weight. 11. The composite material according to claim 1, wherein the bump is made of a composite material having a large number of metal particles and a bonding metal portion which fills gaps between the metal particles and has a lower melting start temperature than a constituent metal of the metal particles. 10. The wiring board with bumps according to claim 9, which is configured. 12. A substrate, which is disposed on a connection surface of the substrate and has a height of 200 μm.
A wiring board with bumps, comprising: a plurality of bumps formed in a column shape of m. 13. A substrate, which is formed of a columnar bump body and a brazing material whose melting start temperature is lower than a constituent material of the bump body, the bump body being disposed on a connection surface of the substrate, A wiring board with bumps, comprising: a plurality of bumps each including a bonding layer bonded to a connection surface.