JPS6188480A - Local heating method and apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention particularly relates to a local gas heating method and apparatus that can set the upper surface of an object to be heated to a desired temperature distribution.

[Background of the invention]

In the method of soldering electronic components onto wiring boards, modules with components with low heat resistance cannot be heated to the solder melting temperature as a whole.
There is a need for a heating method that locally heats only the components to be soldered and minimizes the effect on nearby components with low heat resistance. In this case, from the viewpoint of connection yield and connection reliability, it is important that the solder joint is heated uniformly.

As a conventional local heating method and device, more MTeal
mical Disclosure Bulletin
"HOT GASGLTN' (Tol,
15 No. 3 August 1972). This is a gas heating device that incorporates a heater inside a quartz tube, and at the same time when the heater is energized, gas is introduced from one end of the quartz tube and heated gas is sent out from the other end. At the same time, a method for soldering by spraying gas onto the back side of the chip to be soldered is also shown.

However, in this method, the gas temperature distribution at the gas outlet is determined by the shape of the nozzle tip, so if the shapes, dimensions, heat capacities, and material values of the boards differ, the soldering will vary depending on the part. There were concerns that this would lead to uneven temperature distribution, an increase in connection failures, a decrease in connection reliability, and damage to the board.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned problems and provide a heating method and apparatus that can set the temperature distribution of a heated surface to a desired value.

[Summary of the invention]

The present invention is characterized in that by installing a plurality of heating elements inside the tube and controlling the heating of each heating element independently, the temperature distribution of the heated surface can be set within a desired range. shall be.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 1 to 11.

FIG. 1 is a front view of a gas heating device according to the present invention, and FIG. 2 is a plan view. 1 and 2, for example, inside the quartz tube 2, there are a plurality of heating elements aa, 4h, 4c, 4.
ct, 4t, af, and 4y are arranged, and the respective heating elements are power supply terminals 6α, 6b, and 6C.

6d, 6g, 6f, and 6da (6L65 is not shown). The gas inlet 8 is arranged at the upper part of the power supply terminal board 10, and the lower part of the quartz tube 2 serves as the gas outlet 11. 3 to 5 are isothermal diagrams showing the temperature distribution of the gas heated by the gas heating device shown in FIGS. 1 and 2 in the region of the gas outlet 11.

In the above configuration, gas is fed from the gas inlet 8 and each power supply terminal 6α to 6! By supplying power of a value determined in advance by experiment to I, the heating element 4α ~
4! I is heated, and the gas heated by this heating element is sent out from the gas outlet 11.

Here, by independently supplying desired power to each of the heating elements 4α to 4!1, the gas delivery port 11 is heated.

The gas temperature distribution at the location can be set to a desired value. FIG. 3 shows six heating elements 4α on the outer periphery.

This is the gas temperature distribution when the same power is supplied to 4.6, 4c, 4g, 4f, and 4g, and slightly less power is supplied to the central heating element 4d than to the outer peripheral heating element. In addition, FIG. 4 shows that heating elements AC, 4d, and 4g are heated to high temperature, and heating elements 4α,
FIG. 5 is a gas temperature distribution diagram in which the heating elements 4α, ab*4ct, and 4f t' are set to high temperatures, and the heating element 4C24- is set to a low temperature.

In this way, by individually controlling the amount of power supplied to the heating elements, the shape of the gas temperature distribution can be varied in various ways. Therefore, by determining the optimal temperature distribution shape in advance for objects to be heated that have different shapes, sizes, and heat capacities, it is possible to always perform heat treatment on different parts under optimal conditions with good reproducibility.

6 and 7 show other embodiments in which the cross-sectional shape of the quartz tube 2 is rectangular and oval; in this case as well,
The same effects as the first embodiment shown in FIGS. 1 and 2 can be obtained.

Still another embodiment is shown in FIGS. 8 to 11. FIG. 8 is a front view, FIG. 9 is a side view, and FIG. 10 is a plan view, showing a method for reflow soldering of LSI chips on a wiring board using the heating method according to the present invention. Moreover, FIG. 11 is a temperature distribution diagram on the wiring board during heating. In each figure, the same reference numerals indicate the same components.

In FIGS. 8 to 10, solder bumps 1 are placed on the top surface of a glass substrate 12 on which a wiring pattern is formed.
The LSI chips 14 having the number 3 are aligned and mounted. A lower shielding plate 17 and an upper shielding plate 18 are installed on the lower and upper surfaces of the substrate 12, with a chip mounting area 15 and an open substrate end 16. Lower shielding plate 1
7 is installed and fixed on a substrate holder (not shown). A resin 19 having a heat resistance of, for example, 150° C. is fixed inside the substrate 12, and the upper shielding plate 18 covers the upper surface of this resin 19 for protection.

A gas heating device i20 is arranged above the substrate 12. This gas heating device 20 has four heating elements arranged in an oval quartz tube 21, each of which can be supplied with electric power independently. 22α, 227, 22c, and 22ct, and has a mechanism (not shown) that can slide horizontally, vertically, and perpendicularly to the plane of the paper in FIG.

In FIG. 11, the portion indicated by the two-dot chain line on the substrate 12 is the chip mounting area 15, and the curved line around the area is the equimixing line 23.

In such a configuration, first, the substrate 12 on which the chip 14 is mounted is installed so that the chip mounting area 15 is located at the center of the open portion of the lower shielding plate 17. Next, the upper shielding plate 18 is installed on the upper surface of the substrate 12. Next, a gas heating device 20 for blowing out heated gas is installed above the chip mounting area 15. Each heating element in the gas heating device 20 has a chip-attached temperature distribution as shown in FIG.

The mounting is preset so that the area 15 and the substrate end 16 are at the same temperature. By heating in this state for a certain period of time, the solder bumps 13 are melted and the substrate 12 and the chip 14 are soldered together. After melting the solder,
After a certain period of time rJj has elapsed, the gas heating device 20 is moved from the bonding part and the bonding part is naturally cooled, thereby solidifying the solder at the connection part and completing the bonding.

In this embodiment, since glass is used for the substrate, if tensile stress is applied to the edge of the substrate, the substrate will easily break, resulting in a fatal defect. As a temperature distribution shape that does not cause such defects, it is effective to heat the chip mounting area 15 and the substrate end 16 with a humidity distribution that makes them the same temperature, as shown in FIG. However, there are cases where LSI chips with different shapes and dimensions are installed in area 15, and each time the chip is installed in area 15.
The heat capacity of the heating element 22 in the gas heating device 20 is different, and when heated under certain conditions, the temperature distribution shape differs depending on the type of chip, which causes the above-mentioned defects.
The amount of power supplied to α, 225, 22C, and 22d can be set to values suitable for each chip shape, and an optimal humidity distribution shape can always be maintained even if the types of chips are different.

〔Effect of the invention〕

As described above, according to the present invention, since the chip mounting area and the edge of the substrate can always be maintained at the same temperature, it is possible to eliminate the generation of tensile thermal stress that causes glass breakage at the edge of the substrate. This makes it possible to completely eliminate glass breakage defects during bonding processing. In addition, since the gas temperature distribution at the heated gas outlet can be selected to a desired value, it is possible to easily select the optimal bonding conditions for various chips with different sizes and heat capacities, and work efficiency is increased. , connection yield, and connection reliability can be greatly improved.

[Brief explanation of drawings]

Fig. 1 is a front view of the gas heating device according to the present invention, Fig. 2 is a plan view of Fig. 1, Figs. 3 to 5g are crosstalk diagrams such as temperature distribution of gas, and Figs. FIGS. 8 to 10 are a front view, a side view, and a plan view of a chip bonding heating method using the gas heating device according to the present invention, and FIG. 11 is a plan view of another gas heating device according to the present invention. FIG. 3 is a temperature distribution isotherm diagram on the upper surface of the substrate. 2.21...Quartz tube, 4.22...Heating element, 12...Substrate, 14...Chip, 15...Chip mounting area, 16...Board end, 20. ...Gas heating device. ＼゛-1-7' Representative Patent Attorney Akio Takahashi 1st η 2nd District 6th 3rd Liability 90 Closed 11th

Claims (2)

[Claims] (1) In a local heating method in which gas is introduced into a tube equipped with a heating element inside, and the heated gas is sent out from one end of the tube, there are multiple units in the tube that can individually control heat generation. 1. A local heating method characterized in that the temperature distribution of a surface to be heated is set within a desired range by providing heating elements and setting the calorific value of each heating element to a desired value. (2) In a local heating device in which gas is introduced into a tube equipped with a heating element inside, and the heated gas is sent out from one end of the tube, there are multiple units in the tube that can individually control heat generation. A local heating device characterized by comprising a heating element.