JP2002270732A - Electronic component with underfill material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably increase workability of filling and productivity of a component, enable perfect filling of a gap with an underfill material and enable mounting of other electronic components on a substrate with high efficiency and high density, in an electronic component which is connected with the substrate via colder bumps and in which the gap between the substrate and the component is filled with the underfill material. SOLUTION: One surface side of an electronic component body 11 is coated with an underfill material 13 so as to expose tips of the solder bumps 12 arranged on the electronic component body 11. From a viewpoint for more stiffly attaching an electronic component 1 on the substrate, a side face of the electronic component body 11 may be coated further with the underfill material 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip size package (hereinafter sometimes simply referred to as "CSP") and a ball grid array package (Ba).
ll Grid Array Package (hereinafter sometimes simply referred to as "BGAP") and the like, which is mounted on a substrate via solder bumps.

[0002]

2. Description of the Related Art In recent years, for the purpose of reducing the size and weight of a liquid crystal display device or the like, a chip-on technology in which a display portion and a driving circuit are integrated has been studied. In this chip-on technique, an electronic component is mounted on a substrate on which patterned wiring is formed on the surface. FIG. 7 is a process chart showing a conventional mounting example. On the lower surface of the electronic component body 11,
An electrode terminal (not shown) is formed, and a solder bump 12 is bonded to the electrode terminal by a predetermined method. The solder bumps 12 are opposed to each other on electrode terminals (solder cream) 21 formed on the substrate 2 (step (d)), and the electrode terminals are connected by the solder bumps 12 to place the electronic component 1 on the substrate 2. Mount (process (e)). Then, the solder bumps 12 and the solder cream 21 are melted and integrated in a reflow furnace to form solder S, and the electronic component 1 is fixed on the substrate 2 (step (f)). next,
A gap P between the electronic component 1 and the glass substrate 2 is filled with an underfill material 13 such as an epoxy resin (step (g)). Then, the underfill material 13 is cured by heating to secure the bonding strength of the electronic component 1.

[0003]

However, after mounting the electronic component 1 on the glass substrate 2, the underfill material 1
It takes a lot of trouble to completely fill the void portion P with 3. Further, it is necessary to leave the underfill material 13 filled in the void portion P at a high temperature for a long time to cure it. Furthermore, there is a problem that the underfill material 13 cannot be completely filled in the gap P, that is, if there is an unfilled portion in the gap P, when the external force is applied, the gap is separated from the portion. In addition, in order to secure a work area for filling the gap P of the electronic component 1 mounted on the glass substrate 2 with the underfill material 13, other electronic components such as ICs and capacitors are separated from the periphery of the electronic component 1. It has to be mounted on a substrate, which is a great constraint on the layout design of electronic components.

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and has been developed for an electronic component which is connected to a substrate via a solder bump and has a gap between the substrate and the underfill material filled with an underfill material. To provide an electronic component that can significantly improve the workability of filling and the productivity of components, can completely fill the gap with an underfill material, and can mount other electronic components on a substrate with high efficiency and high density. Is the purpose.

[0005]

According to the present invention, a solder bump is provided on one surface of a chip size package main body, and one surface of the main body is covered with an underfill material so that the tip of the solder bump is exposed. An electronic component is provided.

Here, from the viewpoint of mounting the electronic component more firmly on the substrate, the side surface of the main body may be further covered with an underfill material.

The underfill material is a material which becomes liquid by heating in a solid state at normal temperature, and becomes liquid when heated to a temperature near the melting temperature of solder. Is desirable. For example, a resin containing at least two resins having different melting points is desirable. Hereinafter, for convenience of description, a resin having a higher melting point may be referred to as a “high melting point resin” and a resin having a lower melting point may be referred to as a “low melting point resin”.

Further, from the viewpoint of preventing a short circuit between solder bumps (so-called solder bridge) from occurring when the solder is melted, it is preferable to include a flux agent in the underfill material.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The inventor of the present invention has conducted intensive studies as to whether or not an underfill material can be easily and completely filled in a gap between solder bumps. As a result, before mounting an electronic component on a board, The inventor has found that it is sufficient to previously fill the gap between the solder bumps provided on the electronic component with an underfill agent, and has accomplished the present invention. According to such a configuration, the gap between the solder bumps provided on the electronic component can be filled with the underfill material without any gap, and the filling workability is excellent. Further, it is not necessary to secure a work area for filling the void portion with the underfill material on the substrate on which the electronic component is mounted, and the electronic component can be mounted on the substrate with high efficiency and high density.

Hereinafter, the electronic component of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the electronic component of the present invention. Electronic component 1 of FIG.
A solder bump 12 is formed on an electrode (not shown) of the electronic component body 11, and a layer of an underfill material 13 is formed in a gap P between the solder bumps 12 so that the tip of the solder bump 12 is exposed. It is formed.

The underfill material used here is heated to a predetermined temperature, for example, about 80 to 100 ° C. in a solidified state at normal temperature, as understood from the method for manufacturing an electronic component of the present invention described later. Therefore, it is necessary that the material be a material that becomes liquid, further causes a chemical reaction when heated to about 180 to 240 ° C., and hardens strongly in a process of cooling thereafter. In order to have such features,
What is necessary is just to contain two resins with different melting points. As an example, examples of the low melting point resin include a resin having a hydroxyl group, for example, polyethylene glycol or polypropylene glycol whose molecular weight is adjusted so that the melting point is about 80 to 100 ° C. On the other hand, examples of the high melting point resin include a higher carboxylic acid compound having a carboxyl group.

It is recommended that a flux agent be added to the underfill material in order to prevent a short circuit between the solder bumps, that is, a so-called solder bridge. When the flux agent is added, even if both the underfill material and the solder are melted, they are not fused at all, and the occurrence of a solder bridge is prevented. A conventionally known flux agent can be used, and for example, a rosin-based flux agent and the like can be used.

An inorganic material having a small thermal expansion coefficient, such as calcium carbonate, quartz powder, silicon carbide, or silicon nitride, may be added to the underfill material in order to approximate the thermal expansion coefficient of the electronic component body or the substrate. . The amount of addition is preferably 50 parts by weight or less based on 100 parts by weight of the unfilled underfill material. Further, rubber particles such as polybutadiene and silicon may be dispersed and added to alleviate stress concentration and strain. The additive amount is as follows.
It is preferably 20 parts by weight or less based on 0 parts by weight.

The gap between the substrate and the electronic component is generally 30 to 9
Since the thickness is within the range of 0 μm, the height of the solder bumps for connecting the electronic component body and the substrate in a conductive manner needs to be about this height. The height of the tip of the solder bump exposed from the surface of the underfill material is such that the solder bump can contact the electrode formed on the surface of the board, and the material and shape of the solder bump and the shape of the board electrode are taken into consideration. It may be appropriately determined, for example, about 1 to 10 μm. On the other hand, if the tip portion of the solder bump is excessively exposed on the underfill surface, the gap between the electronic component and the substrate becomes large, and the gap may not be sufficiently filled with the underfill material provided in the electronic component. .

A known method may be used to form solder bumps on the electronic component body. For example, after a metal that is compatible with solder is metallized on the entire surface of the circuit element surface of the wafer by vapor deposition or sputtering, a predetermined method is used. A method in which solder is vapor-deposited at the electrode positions described above, or a method in which electrolytic plating is performed to form solder bumps can be used. The shape of the solder bump is not particularly limited, and may be a conventionally known shape such as a sphere, a drum, or a cylinder. As the composition of the solder to be used, for example, conventionally known solders such as Pb-Sn, Pb-Ag, Bi-Sn, Zn-Cd, and Pb-Sn-Sb are exemplified. Among them, Pb-5% Sn, Pb-60% Sn, and Sn-3.5% Ag are preferable because of their excellent thermal fatigue resistance.

The substrate on which the electronic component of the present invention is mounted is not particularly limited. For example, a single substrate made of glass or ceramic material, epoxy containing glass fiber, polyimide containing glass fiber, epoxy containing high modulus and high strength fiber Or polyimide. In addition, the electrode terminals formed on the substrate may be used in combination of one or more of Au, Ag, Cu, Al, Ni or a metal made of solder, and among them, it can be easily formed by a method such as screen printing. From the viewpoint, creamy solder (hereinafter sometimes referred to as “cream solder”) can be preferably used.

Next, a method for manufacturing an electronic component according to the present invention will be described. FIG. 2 is a process chart showing an example of a method for manufacturing an electronic component according to the present invention. First, the electronic component body 11 having the solder bumps 12 formed on one surface side is attached to the electronic component body 11.
The jig 4 is mounted on a jig 4 having a planar shape that matches the outer shape of (a) and having a concave portion 41 that is deeper than the height of the main body ((a) in the figure). Then, the underfill material 13 is poured into the concave portion 41 of the jig 4 (FIG. 2B). Here, the underfill material 13 is composed of the low-melting substance 13 a and the high-melting substance 13.
b, which contains a fluxing agent (not shown) and is heated to the melting point of the low-melting substance or higher and lower than the melting point of the high-melting substance, for example, about 80 to 100 ° C. In a state in which fine-grained high melting point material 13b is dispersed. The amount of the underfill material 13 to be poured is determined by the solder bumps 12 formed on the electronic component body 11.
Is not soaked at the tip. A sectional view taken along line AA of FIG. When the pouring of the underfill material 13 is completed, the underfill material 13 is cooled slowly to room temperature (about 18 to 25 ° C.) in the state as it is. When the underfill material 13 is solidified, the electronic component 1 is taken out of the jig 4 (FIG. 3C).

The electronic component of the present invention thus manufactured is mounted on a substrate, for example, as follows. FIG. 3 is a process chart showing the mounting of the electronic component of the present invention on a substrate. Solder cream 2 applied on electrode terminals of substrate 2
1, the electronic component 1 is positioned so that the solder bumps 12 face each other (FIG. 4D). Then, when the electronic component 1 is mounted on the substrate 2, the solder bumps 12 are immersed in the solder cream 21 (FIG. 4E). In this state, the substrate 2
In a reflow oven and heated. Substrate 2 is 80-100
When heated to about ° C., the low-melting substance 13a first melts and the underfill material 13 flows, and the electronic component body 11
The space P between the substrate and the substrate 2 is filled (FIG. 6F). At this time, the flux agent (not shown) contained in the underfill material 13 is also melted at the same time, but the high melting point material 13b is dispersed in the low melting point material 13a as fine particles. Then, it is further heated to a temperature higher than the melting point of the high melting point material, for example, 18
When the temperature reaches about 0 to 240 ° C., the high-melting substance 13b is melted and comes into liquid contact with the low-melting substance 13a. Also solder bump 1
2 and the solder cream 21 are also melted, and the two are fused to form a solder S ((g) in the figure). The underfill material 13
Even when the solder S is in a molten state, it does not fuse. Further, due to the action of the flux agent in the underfill material 13, the adjacent solder bumps 12 do not come into contact with each other and fuse. Next, the substrate 2 is slowly cooled to room temperature (FIG. 9H). Underfill material 13 and solder S
Solidifies when the temperature of the substrate 2 falls below the respective melting points. As a result, the electronic component body 11 and the board 2
And the gap P is filled with the underfill material 13 without gaps.

Table 1 summarizes the state changes of the underfill material, the solder, and the flux agent in each step of the above-described method of manufacturing the electronic component and the method of mounting on the substrate according to the present invention.

[0020]

[Table 1]

In Table 1, in the step (b) of coating one surface of the electronic component with the underfill material, the low-melting substance and the fluxing agent are turned into a liquid state, and the one-side is coated with the fine high-melting substance. Flow and charge. Then, in the step (c) of cooling to room temperature, the low-melting-point substance and the flux agent are also solidified, and one side of the electronic component body is covered with an underfill material. The electronic component of the present invention is stored and transported in this state.

In the step of mounting the electronic component on the substrate, a step (d) of placing the electronic component on the substrate with the solder bumps facing the solder cream applied on the substrate;
In the step (e), the high-melting substance and the low-melting substance, the flux agent, the solder bumps, and the solder cream are all in a solidified state. Next, in the step (f) of heating to about 80 to 100 ° C., the low-melting substance and the flux agent become liquid, and the underfill material flows and fills the voids. And about 180
In the step (g) of heating to up to 240 ° C., the high melting point material, the solder bumps, and the solder cream also become liquid, and the high melting point material and the low melting point material, and the solder bumps and the solder cream are mixed in a liquid state respectively. A strong bonding force is generated by contact between the solder bump and the low melting point material, and the solder bump and the solder cream are uniformly fused. Then, in the step (h) of cooling to room temperature, all of the high-melting substance and the low-melting substance, the flux agent, the solder bumps, and the solder cream are again solidified, and the high-melting substance and the low-melting substance are strongly bonded by liquid contact. A force is generated, and the solder bump and the solder cream are integrated into a reliable and strong connection.

Next, another embodiment of the electronic component according to the present invention will be described. FIG. 4 is a perspective view showing another embodiment of the electronic component according to the present invention. The difference from the electronic component shown in FIG.
This is the point covered with.

FIG. 5 shows an example of a method for manufacturing such an electronic component. FIG. 5 is a schematic process diagram of the manufacturing method, and FIG.
The difference from the process diagram shown in FIG. 13 is that the planar shape of the concave portion 41 that accommodates the electronic component body 11 is larger than the planar shape of the electronic component body 11 in the process (a). Thereby, when the electronic component main body 11 is accommodated in the concave portion 41, a predetermined gap is formed between the electronic component main body 11 and the peripheral wall of the concave portion 41. When the underfill material 13 is poured into the concave portion 41, the gap is also filled with the underfill material 13, and after cooling and solidifying, the electronic component 1 is taken out of the jig. The electronic component 1 in which the formation surface and the side surface of the solder bump 12 are covered with the underfill material 13 is obtained.

FIG. 6 shows an example of a process diagram when the electronic component 1 is mounted on the substrate 2. The mounting method shown in FIG.
Since the mechanism is the same as that described above, the description thereof will be omitted, and only different points will be described. That is, the electronic component body 1
The underfill material 13 covering the side surface of the electronic component 1 is melted by heating in a reflow furnace and flows on the substrate 2 to form a fillet F between the side surface of the electronic component body 11 and the substrate 2. Thereby, the bonding strength of the electronic component 1 to the substrate 2 is improved, and the electronic component 1 is effectively prevented from peeling off from the substrate 2.

[0026]

According to the electronic component of the present invention, the underfill material is previously formed on one surface of the electronic component body so that the tip of the solder bump is exposed. The work of filling the fill material is not required, and the productivity of electronic components is greatly improved, and other electronic components can be mounted on the substrate with high efficiency and high density. In addition, since the underfill material is filled in the gap without any gap, the electronic component can be firmly bonded to the substrate.

Further, if the side surface of the electronic component body is also covered with the underfill material, the electronic component melts and becomes a fillet when mounted on a substrate, thereby increasing the adhesive strength of the electronic component.

When the underfill material contains two or more resins having different melting points, the production of electronic components becomes easy, and the electronic components can be more firmly bonded to the substrate.

Further, when the underfill material contains a flux agent, it is possible to effectively prevent a solder bridge in which molten solder bumps come into contact with each other at the time of mounting an electronic component and short-circuit occurs.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an electronic component according to the present invention.

FIG. 2 is a process chart illustrating an example of a method for manufacturing the electronic component in FIG.

FIG. 3 is a process chart showing an example of mounting the electronic component of FIG. 1 on a substrate.

FIG. 4 is a perspective view showing another embodiment of the electronic component according to the present invention.

5 is a process chart showing an example of a method for manufacturing the electronic component in FIG.

6 is a process chart showing an example of mounting the electronic component of FIG. 4 on a substrate.

FIG. 7 is a process chart showing a conventional mounting of an electronic component on a substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electronic component 2 Substrate 11 Electronic component main body 12 Solder bump 13 Underfill material 13a Low melting material 13b High melting material

Claims (4)

[Claims] 1. An electronic component, wherein a solder bump is provided on one surface side of an electronic component main body, and one surface side of the main body is covered with an underfill material so that a tip end of the solder bump is exposed. 2. The electronic component according to claim 1, wherein a side surface of said main body is also covered with said underfill material. 3. The electronic component according to claim 1, wherein the underfill material includes at least two resins having different melting points. 4. The electronic component according to claim 1, wherein the underfill material contains a flux agent.