JPH07326852A - Solder bump forming device - Google Patents

Abstract

PURPOSE:To provide a solder bump forming device generating no bridge which becomes the cause of short circuit by the fused cream solder flowing to sideways when a bump is formed by heat-melting the cream solder on the electrode of a substrate. CONSTITUTION:The solder bump forming device is composed of a conveyor 4 which conveys a substrate 5 where cream solder 7 is applied on an electrode from the inlet 2 of a heating furnace 1 toward the outlet, preheating heaters 10 and 11 with which the substrate 5 is heated up close to the temperature at which the cream solder 7 is fused, and a heat source 12 with which the cream solder 7 is heated up by a small number of quantity to its fusing temperature or higher by projecting heat ray R to the heated cream solder 7. Accordingly, the cream solder 7 is not fused simultaneously, and as it is fused little by little, no bridge is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solder bump forming apparatus for forming a solder bump by heating and melting a solder portion such as cream solder or a solder ball formed on an electrode of a substrate.

[0002]

2. Description of the Related Art In the process of forming bumps (protruding electrodes) on electrodes on the surface of a substrate, cream solder is applied spotwise on the electrodes by a screen printing device, or solder balls are mounted on the electrodes. Then, a step of forming a solder portion and a step of sending the substrate to a reflow device to heat the substrate to melt the solder portion and then cooling to solidify the solder portion are included.

A reflow apparatus is disclosed in, for example, Japanese Patent Laid-Open No. 2-235.
As disclosed in Japanese Patent No. 568, a heater, a fan, and a conveyor are arranged inside a heating furnace, and while the substrate is conveyed from the inlet to the outlet of the main body box by the conveyor, hot air is blown by the fan. Spray it onto the board,
The solder portion is heated to the melting temperature or higher to melt it.

[0004]

A large number of solder portions are formed in high density at positions close to each other on a board.
In the conventional reflow equipment, these many solder parts are heated to the melting temperature at the same time and melted all at once, so that there is an advantage that the work efficiency is good, but the melted solder parts flow out to the side and the adjacent solder parts There has been a problem that a bridge that easily connects the parts and causes a short circuit easily occurs.

Therefore, an object of the present invention is to solve the above-mentioned conventional problems and to provide a solder bump forming apparatus in which bridging is less likely to occur.

[0006]

To this end, the present invention is directed to a heating furnace, a conveyor for carrying a substrate having a solder portion formed on an electrode from an inlet to an outlet of the heating furnace, and a solder for the substrate. The preheater that heats the solder to a temperature close to the melting temperature and the solder that has been heated to a temperature near the melting temperature are irradiated with heat rays with a specified irradiation width to heat the solder to a small number above the melting temperature to melt it. A solder bump forming apparatus is configured from a source.

[0007]

In the above structure, the preheating heater heats the solder portion to a temperature close to the melting temperature, and then a small number of the solder portions are heated to a melting temperature or higher to melt the solder portion to form bumps.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the drawings. 1 is a sectional view of a solder bump forming apparatus according to an embodiment of the present invention, FIG. 2 is a partially enlarged side view of the solder bump forming apparatus, and FIG. 3 is a description of a bump forming process by the solder bump forming apparatus. It is a figure. In FIG. 1, reference numeral 1 is a heating furnace, and an inlet 2 is opened in the front surface thereof, and an outlet 3 is opened in the rear surface thereof. A conveyor 4 conveys the substrate 5 from the entrance 2 to the exit 3. As shown in FIG. 2, the cream solder 7 (solder portion) is applied on the electrodes 8 formed in high density on the upper surface of the substrate 5 in a matrix.

In FIG. 1, a first unit is provided above the conveyor 4.
Is provided with a preheater heater 10 and a second heater is provided below.
The preheater 11 is provided. The first preheater 10 and the second preheater 11 heat the substrate 5 to near the melting temperature of the cream solder 7. The melting temperature of the solder is generally about 183 ° C., and therefore the first preheater 1
0 and the second preheater 11 have the cream solder 7 of 150
The substrate 5 is heated to about 170 ° C.

A heating source 12 is provided at a slightly rear portion of the heating furnace 1. Reference numeral 13 is a reflecting plate disposed above the heating source 12. The heating source 12 is, for example, a laser irradiator or a focused infrared irradiator, and irradiates the cream solder 7 with a heat ray R from above to rapidly heat the cream solder 7.
This heating source 12 has a predetermined irradiation width D (FIG. 2) in the transfer direction N of the substrate 5, so that the heat ray R is not irradiated to all the cream solders 7 at the same time, and a small number of the cream solders 7 are formed. It is irradiated every time. A fan 14 is provided immediately before the outlet 3 of the heating furnace 1, and the fan 14 and the heating source 12 are partitioned by a partition wall 15. 16 is fan 1
4 is a motor that rotates. When the fan 14 rotates, air is blown onto the substrate 5 to cool the substrate 5.

The solder bump forming apparatus is constructed as described above, and its operation will be described below. The substrate 5 is conveyed by the conveyor 4 from the inlet 2 to the outlet 3 of the heating furnace 1, while the first preheater 10 and the second preheater 11 keep the substrate 5 close to the melting temperature of the cream solder 7. It is gradually heated up to about 150 to 170 ° C. Next, the cream solder 7 passes under the heating source 12, but at this time, the heating wire 12 irradiates the heat ray R,
The cream solder 7 is rapidly heated to the melting temperature (183 ° C.) or higher. Initially, the cream solder 7 has a square cross-section as shown in FIG. 3A, but when it is heated by the heating wire of the heating source 12 and melted, the shape is collapsed as shown in FIG. It becomes a fixed form. Subsequently, the melted cream solder 7 becomes a hemisphere due to its own surface tension (FIG. 3C). Next, the substrate 5 passes below the fan 14, at which time the air is blown to cool the cream solder 7, and the cream solder 7 solidifies into hemispherical bumps 7 and is sent out from the heating furnace 1.

In the above operation, as shown in FIG. 2, the heat ray R has a constant irradiation width D. Therefore, the heat ray R is not applied to all the cream solders 7 at the same time, but is applied to each of the small number of cream solders 7, preferably to each of the cream solders 7 at one place. For this reason, all the cream solders 7 do not melt at the same time at the same time, but a small number of them melt in each horizontal row, so that bridging is unlikely to occur. A bridge is unlikely to occur between them. When the cream solder 7 melts,
The conveyance of the substrate 5 by the conveyer 4 may be completely stopped or the conveyance speed may be reduced. By doing so, the cream solder 7 melted by the vibration during the conveyance flows out to the side. It is possible to further prevent a bridge from occurring. Although the present invention does not prohibit the installation of a fan for blowing the hot air heated by the first preheater 10 and the second preheater 11 onto the substrate 5, the fan is removed as in this embodiment. Therefore, the substrate 5 is hit by the hot air to fall off the conveyor 4, or the cream solder 7 melted due to the substrate 5 being hit by the hot air flows laterally to form a bridge. Can be eliminated.

The present invention is not limited to the above-described embodiment. For example, instead of the cream solder 7, solder balls may be adhered to the electrodes 8 with flux and the solder balls may be heated and melted to form bumps. The number of heating sources may be any number. Further, a laser oscillator that irradiates a spot laser beam having a predetermined diameter may be used as a heating source, and the spot laser beam may be sequentially irradiated to the cream solder to melt the cream solder one by one.

[0014]

As described above, according to the present invention, the substrate is preheated by the preheater to a temperature close to the melting temperature of the solder portion, and then the solder portion is heated by the heating wire of the heating source to melt the solder in small numbers. Therefore, a bump having a good shape can be formed while preventing the occurrence of a bridge that causes a short circuit.

[Brief description of drawings]

FIG. 1 is a sectional view of a solder bump forming apparatus according to an embodiment of the present invention.

FIG. 2 is a partially enlarged side view of a solder bump forming apparatus according to an embodiment of the present invention.

FIG. 3 is an explanatory view of a bump forming process by a solder bump forming apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 1 Heating Furnace 2 Inlet 3 Outlet 4 Conveyor 5 Substrate 7 Cream Solder (Solder) 8 Electrode 10 First Preheater 11 Second Preheater 12 Heating Source

Claims (1)

[Claims] 1. A heating furnace, a conveyor for carrying a substrate having a solder portion formed on an electrode from an inlet to an outlet of the heating furnace, and a preheating heater for heating the substrate to a temperature close to the melting temperature of the solder portion. , A solder characterized by comprising a heating source that heats and melts a small number of solder portions to a melting temperature or higher by irradiating the solder portion heated to near the melting temperature with a heat ray with a predetermined irradiation width. Bump forming device.