JPS61253164A - Local heating method - Google Patents

Abstract

PURPOSE:To reduce the rupture of a substrate and to improve working efficiency by providing flow regulating plates into a gas delivery port of a gas heating pipe contg. a heating element and setting the temp. distribution of the heating gas in the delivery part to the desired state thereby setting the temp. distribution of the surface to be heated in a desired range. CONSTITUTION:The heating element 4 attached to the bottom surface of a terminal board 5 having electric power supply terminals 6A, 6B is housed into the quartz pipe 1A having a feed port 2 and the delivery port 3. Grooves 7A, 7B are provided to the circumferential wall of the port 3 and the flow regulating plates 8 or controlling the flow of the gas are inserted into the grooves. The plates 8 are disposed adequately with many through-holes 9. The element 4 of such heating device 1 heats the gas when the gas is fed through the port 2 into the pipe 1A and the electric power determined preliminarily by experiment is supplied to the terminals 6A, 6B. The heated gas is delivered through the flow regulating plates from the port 3. The temp. of the heated gas in the port 3 is distributed to the flat shape in the high-temp. part where the isothermal lines cover a wide range near the center. Such temp. distribution is determined by how the holes 9 are disposed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a local heating method mainly used when soldering electronic components onto a wiring board.

[Background of the invention]

In the method of soldering electronic components onto a wiring board,
Modules with components with low heat resistance cannot be heated as a whole to the melting temperature of the solder.

For this reason, there is a need for a heating method that locally heats only the part to be soldered and minimizes the effect on low heat resistant components in the vicinity. In this case, from the standpoint of connection yield and connection reliability, it is important to uniformly heat the solder joints.

As a conventional local heating method and device, IBM
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There is one shown in Gas Gun J (HOT GA8 GTJN).

This gas heating device has a heater built into a quartz tube, and is configured to energize the heater, simultaneously introduce gas from one end of the quartz tube, and send out heated gas from the other end. The above-mentioned document also describes a method for bonding by spraying the heated gas generated by this gas heating device onto the back surface of the chips to be soldered.

However, in the above method, the gas temperature distribution at the gas outlet is determined by the shape of the nozzle tip. For this reason, if the shapes, dimensions, heat capacities, and board materials of the parts to be soldered differ, the temperature distribution during soldering will be uneven, leading to an increase in connection failures, a decrease in connection reliability, and damage to the board. There were concerns that this would lead to

[Purpose of the invention]

The present invention solves the problems of the conventional technology as described above, and by setting the temperature distribution of the heated surface within a desired range, it improves work efficiency and reduces equipment costs, and significantly improves connection reliability. The purpose is to improve

[Summary of the invention]

In order to achieve the above object, the present invention has an inlet and an outlet, and introduces gas through the inlet into a tube containing a heating element, and heats the heated gas sent out from the outlet to generate local heat. In the local heating method, a current plate is provided in the outlet of the pipe, and the temperature distribution of the heated gas at the outlet is set to a desired state, thereby setting the temperature distribution of the heated surface to a desired range. It is characterized by being made to do.

[Embodiments of the invention]

Hereinafter, an embodiment of the local heating method of the present invention will be described with reference to the drawings. 1 and 2 are a front view and a plan view of a local heating device to which an embodiment of the local heating method of the present invention is applied.

In the figure, a heating element 4 attached to the lower surface of a terminal board 5 containing power supply terminals 6A and 6B (hereinafter referred to as terminals) is housed in a quartz tube having an inlet 2 and an outlet 5. ing. The terminal board 5 is attached to the outer periphery of the inlet 2. Also, @7A, 7B are provided on the peripheral wall of the outlet 3.
A rectifier plate 8 (see FIG. 3) for controlling the flow of gas is inserted into #47A and #47B. A large number of through holes 9 are appropriately arranged in the current plate 8.

In the heating device 1 configured as described above, when gas is introduced into the pipe 1A through the inlet 2 and electric power of a value determined in advance by experiment is supplied to the terminals 6A and 6B, the heating element 4 generates heat. Heat the gas. This heated gas is sent to outlet port 3.
The liquid is sent out through rectifier plates (not shown) inserted into the grooves 7A and 78, respectively.

In this case, the temperature distribution along the longitudinal center line 0 of the outlet port 3 will be as shown by the solid line α in FIG. state. That is, it was confirmed from the measurement results that the isothermal ffa10 spreads over a wide range near the center of the outlet 3, forming a flat temperature variation distribution in the high temperature region where the isothermal region changes.

The temperature distribution of the flat shape of the high-temperature part is as shown in FIG.
Since the temperature distribution is determined by the arrangement of a large number of through holes 9, by using a current plate in which the arrangement of the through holes 9 is changed, it is possible to easily obtain another desired temperature distribution.

When the baffle plate is not used, a mountain-shaped temperature distribution is formed with the apex near the center of the outlet 3 as shown by the broken line in FIG. 4 and the isothermal line 11 in FIG. 6.

7 to 10 show examples of application of the preheating device. That is, FIGS. 7 to 9 are a front view, a side view, and a plan view, respectively, illustrating a method of soldering reflow bonding an LSI chip onto a wiring board using a heating device to which the heating method of the present invention is applied. FIG. 10 is a temperature distribution diagram of the wiring board during heating. Among the reference numerals in these figures, the same reference numerals indicate the same or corresponding parts.

In FIGS. 7 to 9, an LSI chip 22 having solder bumps 21 is positioned and placed on the upper surface of a glass substrate 20 on which a wiring pattern (not shown) is formed. Further, on the upper and lower surfaces of the board 20, an upper shielding plate 25 and a lower shielding plate 26 are installed, respectively, in which a chip mounting area 23 and a board end 24 are open. A holder (not shown) is fixed to Ic. Further, a heat-resistant member such as a resin 27 having a temperature of 160° C. is fixed inside the substrate 20, and the upper surface of the resin 27 is covered with an upper shielding plate 25.

A gas heating device 1 is installed above the substrate 20, and the gas heating device 1 includes a heating element (not shown) for heating gas in a quartz tube. The delivery section 3 is formed in an elongated cylindrical shape, and has a structure in which rectifier plates 8A and 8B are provided for controlling the gas flow rate distribution within the delivery section. Such a gas heating device 1 is equipped with a mechanism (not shown) that can slide in the left-right direction, the up-down direction, and the direction perpendicular to the plane of the paper in FIG.

Next, a case will be described in which the chip 22 is connected by solder reflow onto the wiring board 20.

First, the substrate 20 on which the chip 22 is mounted is installed so that the chip mounting area 23 is located in the center of the open part of the lower shielding plate 26. Next, after installing the upper shielding plate 25 on the upper surface of the substrate 20, the gas heating device 1 blowing out the heating gas is moved so as to be located above the chip mounting area 23. By heating in this state for a certain period of time, the solder bumps 21 are melted and the wiring pattern on the substrate 20 and the chip 22 are soldered together.

After the solder melts as described above and a certain period of time has elapsed, the gas heating device 1 is moved away from the bonding part and the bonding part is naturally cooled, whereby the solder at the connection part solidifies and the bonding is completed.

In this embodiment, since a glass plate is used for the substrate 20,
If tensile stress is applied to the substrate end 24, the substrate 20 may easily break, resulting in a fatal failure. As for the temperature distribution that does not cause such defects, it is effective to surround the area 23 with two isometric lines for chip mounting as shown in FIG. .

Therefore, in this embodiment, the current plate 8A having the same structure as that in FIG.
, 8B, it was possible to realize an isothermal distribution consisting of isothermal lines 28 as shown in FIG.

〔Effect of the invention〕

As explained above, according to the present invention, by providing an appropriate rectifying plate at the gas outlet, it is possible to easily realize a temperature distribution suitable for the heated product. It is possible to significantly reduce the number of broken glass substrates that have previously been used, and to improve work efficiency.

In addition, by reducing the variation in temperature between the connection points of the frequently connected component, connection reliability can be significantly improved.

[Brief explanation of drawings]

1 and 2 are front and side views of a heating device to which the local heating method of the present invention is applied, FIG. 6 is a plan view of a rectifier plate used in the local heating method of the present invention, and FIGS. FIG. 6 is an explanatory diagram of temperature distribution in the local heating method of the present invention and the conventional method, and FIGS. 7 to 9 are a front view, a side view, and a plan view, respectively, illustrating a method for soldering reflow connection of chips on a wiring board. , FIG. 10 is a temperature distribution diagram of the wiring board during heating. 1 person...pipe, 2...inlet, 3...outlet, 4...
... Heating element, 8... Rectifier plate. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure q

Claims (1)

[Claims] In a local heating method in which gas is introduced from the inlet into a tube having an inlet and an outlet and a heating element is built in, and a local area is heated by the heated gas sent out from the outlet, the outlet of the tube A local heating method characterized in that the temperature distribution of the heated surface is set within a desired range by providing a rectifier plate inside the outlet and setting the temperature distribution of the heated gas at the outlet to a desired state. .