JPH0341952B2 - - Google Patents

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 a wiring board, since it is not possible to heat the entire module to the solder melting temperature for modules that have components with low heat resistance, only the components to be soldered are locally heated. There is a need for a heating method that minimizes the effect on nearby parts 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, IBM
“HOT” in Technical Disclosure Bulletin
GAS GUN” (Vol. 15 No. 3 August 1972). This method incorporates a heater inside a quartz tube, and at the same time supplies electricity to the heater, gas is introduced from one end of the quartz tube. This is a gas heating device that sends out heated gas from the other end, and a method for soldering by spraying the heated gas generated by this device onto the back surface of the chips 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.
If the dimensions, heat capacity, and board materials differ, the temperature distribution at the soldering area will be uneven, leading to an increase in connection failures,
There were concerns that this would lead to 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 a local heating method and device for locally heating a soldering part in order to solder connect electronic components to a wiring board. The soldering part is heated locally by blowing gas heated to a predetermined temperature distribution by a pipe provided in the soldering part.

[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;
FIG. 2 is a plan view. 1 and 2, for example, a plurality of heating elements 4a, 4b, 4c, 4d, 4e, 4f, and 4g are arranged inside the quartz tube 2, and each heating element is connected to the power supply. Terminals 6a, 6b, 6c, 6d, 6e, 6f, 6g
(6f, 6g are 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, the heating elements 4a to 4g are heated by feeding gas through the gas inlet 8 and supplying electric power of a value determined in advance through experiments to each power supply terminal 6a to 6g. Gas heated by the gas is sent out from the gas delivery port 11.

Here, by independently supplying desired power to each heating element 4a to 4g, the gas temperature distribution at the position of the gas outlet 11 can be set to a desired value. FIG. 3 shows six heating elements 4a on the outer periphery,
This is the gas temperature distribution when the same power is supplied to 4b, 4c, 4d, 4e, 4f, and 4g, and slightly less power is supplied to the central heating element 4d than to the outer peripheral heating element. FIG. 4 also shows heating elements 4c, 4d, 4.
FIG.
It is a gas temperature distribution diagram when heating elements a, 4b, 4d, 4f, and 4g are set to high temperatures and heating elements 4c and 4e are set to low temperatures.

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. For this reason, the shape, size,
By determining the optimal temperature distribution shape in advance for objects to be heated that have different 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, but in this case as well, the first embodiment shown in FIGS. 1 and 2 is used. The same effect as in the example 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, on the upper surface of the glass substrate 12 on which the wiring pattern is formed,
An LSI chip 14 having solder bumps 13 is 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. The lower shielding plate 17 is installed and fixed to a substrate holder (not shown). Inside the substrate 12 is a resin 19 with a heat resistance of, for example, 130°C.
is fixed, and the shielding plate 18 is made of this resin 1.
9 is worn on top for protection.

A gas heating device 20 is arranged above the substrate 12. This gas heating device 20 has four heating elements 22a, 22b,
22c and 22d, 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 a two-dot chain line on the substrate 12 is the chip mounting area 15, and the curved line around the area is the isothermal line 23.

In such a configuration, first the lower shielding plate 17
The substrate 12 on which the chip 14 is placed is installed so that the chip mounting area 15 is located in the center of the open part. Next, the upper shielding plate 1 is placed on the upper surface of the substrate 12.
Install 8. Next, a gas heating device 20 that blows out heated gas is installed above the chip mounting area 15. Gas heating device 2
Each of the heating elements in 0 is set in advance so that the temperature distribution of the chip mounting area 15 and the board end 16 are equal in temperature, as shown in FIG. By heating in this state for a certain period of time, the solder bumps 13 are melted,
The substrate 12 and the chip 14 are soldered together. After melting the solder, the gas heating device 20 is moved from the bonding section after a certain period of time has passed, and the bonding section is naturally cooled, thereby solidifying the solder at the connection section 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. The 11th temperature distribution shape that prevents such defects from occurring is
As shown in the figure, it is effective to heat the chip mounting area 15 and the substrate end 16 with a temperature distribution that makes them the same temperature. However, chip installation area 15
LSI chips with different shapes and dimensions may be attached to the chip, and the heat capacity in the chip mounting area 15 differs each time, and when heated under certain conditions, the temperature distribution shape differs depending on the type of chip, which is the cause of the above-mentioned defects. However, in the present invention, the heating elements 22a, 22b, 22c,
The amount of power supplied to 22d can be set to a value suitable for each chip shape, and an optimal temperature distribution shape can always be ensured 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. It is possible to completely eliminate glass breakage defects during bonding treatment. 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 dimensions and heat capacities, which increases work efficiency. , connection yield, and connection reliability can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is a front view of a gas heating device according to the present invention;
FIG. 2 is a plan view of FIG. 1, FIGS. 3 to 5 are temperature distribution isotherms of gas, FIGS. 6 and 7 are plan views of other gas heating devices according to the present invention, and FIGS. FIG. 10 is a front view, side view, and plan view of a chip bonding heating method using a gas heating device according to the present invention, and FIG. 11 is a temperature distribution isotherm diagram on the upper surface of a substrate during chip bonding. 2, 21...Quartz tube, 4,22...Heating element, 12...
Substrate, 14... Chip, 15... Chip attachment area, 16... Substrate end, 20... Gas heating device.

Claims (1)

[Scope of Claims] 1. A local heating method for locally heating a soldered part for soldering electronic components to a wiring board, the method comprising a plurality of heating elements whose heat generation amount can be independently controlled. Gas is fed into a tube built in the direction, and the gas heated to a predetermined temperature distribution in a plane perpendicular to the ventilation direction by the heating element is sent out from the tube to locally touch the soldering part. A local heating method characterized by heating. 2. A local heating device that locally heats a soldering part for soldering electronic components to a wiring board, which includes a pipe body that ventilates gas inside the pipe body, and a device installed inside the pipe body in the ventilation direction. A plurality of heating elements whose calorific value can be controlled independently, and a means for independently controlling the calorific value of the heating elements are provided, and by passing through the pipe body, a predetermined position is provided in a plane perpendicular to the ventilation direction. A local heating device characterized by blowing gas heated to a temperature distribution onto the soldering portion to locally heat the soldering portion.