JP3344049B2 - Electronic components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component in which bumps are formed by screen printing means on electrodes formed in a matrix.

[0002]

2. Description of the Related Art As means for reducing the size and density of electronic components such as substrates and chips, a large number of electrodes are formed in a matrix on the surface of the electronic components, and bumps (protruding electrodes) are formed on the electrodes. It is known. Further, as a method for forming a bump, a method is known in which cream solder is applied to electrodes by screen printing means, and then the electronic component is heated in a heating furnace to melt and solidify the cream solder to form a bump.

[0003]

According to the screen printing means, there is an advantage that bumps can be formed at low cost and with good workability. However, when the cream solder is melted by being heated in a heating furnace of a reflow apparatus, the melting point is reduced. There is a problem in that the cream solder flows and uneven fusion or bridges are generated, and defective bump formation is likely to occur. Hereinafter, the reason why the non-uniform fusion or the bridge occurs will be described.

FIG. 7 is a plan view of a conventional electronic component.
On the surface of the electronic component 1, a large number of electrodes 2 are formed in a matrix. After applying cream solder on the electrode 2 by screen printing means, the cream solder is heated and melted and solidified in a heating furnace of a reflow device to form bumps.

FIGS. 8 (a), (b), (c), (d),
(E) is an explanatory view of a conventional process in which nonuniform fusion or bridging occurs in bumps of an electronic component. FIG. 8 (a)
Shows a state in which cream solder 3 is applied on the electrodes 2 on the surface of the electronic component 1 by screen printing means. FIG.
(B) shows a preheating state shortly after the heating of the electronic component 1 in the heating furnace of the reflow device is started. In this state, the cream solder 3 gradually softens and its shape starts to collapse. FIG. 8C shows that the heating proceeds further, the liquid rosin 5 mixed with the cream solder 3 to remove the oxide film on the surface of the solder 4 is liquefied and fluidized, and the solder 4 contained in the cream solder 3 is removed. This shows a molten state. In this state, the molten solder 4 flows out to the side, so that the solders 4 on the adjacent electrodes 2 are connected to each other. FIG. 8D shows a state in which the heating is further advanced and the solder 4 is completely melted. As shown in FIG. 8C, as a result of the connection of the molten solders 4 on the adjacent electrodes 2, the molten solders 4 are flushed to the lower internal pressure (in this example, the left-hand solder 4), and then Upon cooling, the solder 4 solidifies to form a spherical bump 4a. As a result, an excessive bump 4a is formed on the left electrode 2, and no bump is formed on the right electrode 2. Alternatively, as shown in FIG. 8E, the bridge 4 is formed when the solder 4 is cooled and solidified while straddling the adjacent electrodes 2. Such a bridge 6
Are more likely to occur as the pitch of the electrodes 2 is reduced in order to reduce the size and density of the electronic component 1.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an electronic component for forming a bump that can eliminate the occurrence of uneven fusion that causes variation in the size of the bump and the occurrence of a bridge that short-circuits the electrodes or the bumps.

[0007]

SUMMARY OF THE INVENTION For this purpose, the present invention provides a method for applying solder which is heated and melted and flows out to the side to electrodes of an electronic component.
The extending portion attracts a plurality radially from the periphery to the outside
Are those that form form.

[0008]

In the above construction, when the electronic component is heated in the heating furnace to melt the solder, the solder flows out to the side, but the outflowing solder is sucked to the extending portion, so that excessive outflow is prevented. No fusing, non-uniformity, or bridging occurs.

[0009]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of an electronic component according to an embodiment of the present invention, and FIG. 2 is an enlarged view of a portion A in FIG. Electronic component 1
A large number of electrodes 12 are formed in a matrix on the surface of one. As shown in FIG. 2, the planar shape of the electrode 12 of this embodiment is circular, and a plurality of tongue-shaped extending portions 12a radially extend outward from the periphery. 3 and 4 are sectional views of a screen printing machine according to an embodiment of the present invention, and FIG. 4 is a partially enlarged sectional view of the same. In FIG. 3, the screen mask 7 of the screen printing machine is brought close to the upper surface of the electronic component 11 and the squeegee 8 is slid on the screen mask 7 in the direction of the arrow, so that the cream solder 3 is
On the electrode 12. The electrode 12 is formed on the surface of the electronic component 11, and a pattern hole 9 is opened at a position corresponding to the electrode 12 of the screen mask 7. Therefore, by sliding the squeegee 8,
The cream solder 3 is applied on the electrode 12.

Subsequently, the electronic component 11 is sent to a heating furnace of a reflow device and soldered. 5 (a), (b),
(C), (d) and FIGS. 6 (a), (b), (c),
(D) is an explanatory view of a process for generating bumps of an electronic component according to one embodiment of the present invention. FIG. 5 is a partial cross-sectional view of the electronic component 11, and FIG.
(A), (b), (c), (d) and FIG.
(B), (c), and (d) correspond to each other.

FIGS. 5A and 6A show an electronic component 1.
1 shows a state in which the cream solder 3 is applied on the electrode 12 on the surface 1 by screen printing means. FIG. 5B and FIG. 6B show a preheating state immediately after starting heating of the electronic component 11 in the heating furnace of the reflow device. As shown in the figure, in this state, the cream solder 3 gradually softens and its shape starts to collapse.

FIGS. 5 (c) and 6 (c) show that the heating proceeds further, and the liquid rosin 5 mixed with the cream solder 3 for removing the oxide film on the surface of the solder 4 is liquefied and fluidized. This shows a state in which the solder 4 contained in the cream solder 3 is melted. In this state, the molten solder 4 tends to flow out to the side, but the solder 4 is sucked to the extension portion 12a, so that it excessively flows out and the solders 4 on the adjacent electrodes 12 are connected and fused. Non-uniformity or bridging is avoided.

FIGS. 5 (d) and 6 (d) show a state in which the solder 4 is completely melted by further heating, and a substantially spherical bump 4a is generated by the surface tension of the melted solder 4. FIG. I have. As described above, since the solders 4 on the adjacent electrodes 12 are not connected to each other, a spherical bump 4a is generated on each electrode 12 by the surface tension of the solder 4 itself.

As described above, according to this embodiment, even if the cream solder 3 is heated and melted, the melted solders 4 are not connected to each other to form a bridge.
The bumps 4a having a desired shape can be reliably formed on the upper surface.

[0015]

As described above, according to the present invention, the solder which is heated and melted and flows out to the side is sucked to the electrode of the electronic component .
Since the kick extending portion from its surroundings forms form a plurality radially outward and to melt the solder by heating the electronic component in a heating furnace, the solder is flowing laterally, spilled solder Excessive outflow is prevented by being sucked to the extension part, so that non-uniform fusion and generation of a bridge can be eliminated, and bumps of a desired shape having substantially the same size and the same shape are formed on each electrode. be able to.

[Brief description of the drawings]

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

FIG. 2 is an enlarged view of part A of FIG. 1 of the electronic component according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view of a screen printing machine for electronic components according to one embodiment of the present invention.

FIG. 4 is a partially enlarged cross-sectional view of a screen printing machine for electronic components according to an embodiment of the present invention.

5A is a diagram illustrating a process for generating a bump of an electronic component according to one embodiment of the present invention; FIG. 5B is a diagram illustrating a process for generating a bump for an electronic component according to one embodiment of the present invention; Explanatory drawing of a bump generation process of an electronic component according to an embodiment (d) Explanatory diagram of a bump generation process of an electronic component according to an embodiment of the present invention

FIG. 6A is a diagram illustrating a process for generating a bump of an electronic component according to one embodiment of the present invention; FIG. 6B is a diagram illustrating a process for generating a bump for an electronic component according to one embodiment of the present invention; Explanatory drawing of a bump generation process of an electronic component according to an embodiment (d) Explanatory diagram of a bump generation process of an electronic component according to an embodiment of the present invention

FIG. 7 is a plan view of a conventional electronic component.

FIG. 8 (a) Non-uniform fusion with bumps of a conventional electronic component;
(B) Schematic diagram of a process in which a conventional electronic component has a non-uniform fusion or a bridge. (C) Schematic diagram of a process in which a conventional electronic component has a non-uniform fusion or a bridge. Explanatory drawing (d) Explanatory drawing of a process in which a non-uniform fusion or a bridge occurs in a bump of a conventional electronic component (e) Explanatory drawing of a process in which a non-uniform fusion or a bridge occurs in a bump of a conventional electronic component

[Explanation of symbols]

 3 cream solder 4a bump 11 electronic component 12 electrode 12a extension

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05K 3/34 H01L 21/60 H05K 1/02

Claims (1)

(57) [Claims] 1. A cream solder is coated on the electrodes formed in a matrix, an electronic component to have the formed bumps by melting solidified by heating the cream solder, to the electrode, heat melting Solder flowing to the side
Radial extension from the periphery to the outside
Electronic component, characterized in that form shape to.