JPH0770826B2 - IC mounting method using inert gas flow - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for mounting and connecting an IC to a glass substrate or the like common to a liquid crystal display element without causing deterioration of liquid crystal, cracking of the substrate, or the like.

[Background of the Invention]

Conventionally, when mounting ICs on a board, for example, “Soldering technology for electronic materials” (authored by Nao Osawa, published by Kogyo Kenkyukai) 15
As described on pages 9 to 161, soldering was performed by infrared irradiation or local heating by blowing hot air.

However, the infrared irradiation method is not suitable for (a) soldering an IC to a glass substrate or the like that easily causes thermal strain cracks.
(B) When connecting an IC near a low heat resistant temperature (120 ° C) such as liquid crystal, it is difficult to keep the liquid crystal below the heat resistant temperature. (C) In order to prevent oxidative burning of flux, It is necessary to install an active gas blowing mechanism attached to the heating section, which complicates the entire structure of the heating section. (D) There is a change in efficiency of the infrared heater, and it is possible to detect the infrared irradiation temperature and perform feedback control with high accuracy. There are difficulties such as difficulty.

In addition, in the conventional hot air blowing additional heat method, hot air is blown onto one side of the substrate, high-level control of the blowing amount and blowing timing is not performed, and preheating of the substrate by the platen (metal plate) is not performed. Although it requires less equipment than the soldering method, there are problems such as shortening the solder connection time, keeping the periphery of the connection point at a heat resistant temperature or lower, and preventing important points such as board crack prevention.

[Object of the Invention]

The object of the present invention is to prevent the generation of cracks due to thermal strain on the substrate where the IC is soldered, and to protect the low-temperature-resistant substance near the solder connection point by cooling while using a high melting point solder.
With an inert gas flow that can mount and connect the IC to the board in a short time
To provide an IC mounting method.

[Outline of Invention]

In order to achieve the above object, in the present invention, corresponding to the connection portion of the wiring pattern formed on the substrate, an IC having a connection terminal filled with solder for connection is arranged in advance, and the solder connection point has a high temperature. The heated inert gas flow is sprayed locally, and the room temperature cooling inert gas flow is sprayed locally on both the front and back sides of the board, immediately after the solder connection is completed. By a series of operations of blowing an inert gas flow for cooling of, the periphery of the solder connection local part of the board is always kept below the heat resistant temperature, and only the solder connection local part is
The heating process up to a temperature high enough to melt the solder to realize electrical connection and the cooling process to return to normal temperature after the connection is completed can be completed in an extremely short time. Since high-melting point solder is used to improve the reliability of solder connection, the temperature of the hot inert gas sprayed is stabilized by continuously blowing out the hot inert gas while switching the flow rate stepwise. And held at a predetermined value.

Example of Invention

FIG. 1 (a) is a cross-sectional view of an essential part of an embodiment of the present invention.
The LSI chip 2 is temporarily fixed with the flux 2a on the glass substrate 1b near the liquid crystal enclosure 1a of the liquid crystal display element 1.
A metal mask (upper) 3a provided with holes for blowing an inert gas for heating and cooling, respectively, above and below the liquid crystal display element 1.
A metal mask (bottom) 3b is installed. Further, a heating nozzle (upper) 4a, a cooling nozzle (upper) 4b, and a heating nozzle (lower) are provided on the upper part of the metal mask (upper) 3a and the lower part of the metal mask (lower) 3b, respectively. ) 4c and a cooling nozzle (lower) 4d. The heating temperature and the blowing gas flow rate are
Control is performed by temperature controllers 5a and 5b and flow rate regulators 6a and 6b, respectively. The heating nozzle (upper) 4a, the cooling nozzle (upper) 4b, the heating nozzle (lower) 4c, and the cooling nozzle (lower) 4d can be positioned by the pulse controller 7, respectively. The liquid crystal display element 1 is
Normally, it is mounted on a conveyer or the like in a state of being fixed on the platen 8 and carried in and out of this solder connection portion.

Next, a spraying time chart of high-temperature and low-temperature inert gas for heating the solder connection of the LSI chip and cooling the liquid crystal filling portion will be described with reference to FIG. At the timing A, a high temperature (for example, 600 ° C.) gas is blown by the heating nozzle, and at the same time, a small amount of low temperature (for example, 20 ° C.) gas is blown by the cooling nozzle. At the timing B, the heating nozzle is moved to the outside of the solder connection portion, a small amount of high temperature gas is discharged in order to stabilize the spraying temperature, the cooling nozzle is moved to the inside of the solder connection portion, and a large amount of low temperature gas is sprayed. In this embodiment, (a) since the glass substrate (metal film wiring part) of the solder connection part of the LSI chip can be heated with a uniform temperature distribution, cracks due to thermal strain do not occur in the glass substrate. (B) Solder connection part Since the liquid crystal enclosure in the vicinity can be kept below the heat resistant temperature of the liquid crystal, deterioration of the liquid crystal is prevented. (C) High temperature inert gas (N ₂ ) is sprayed on the solder connection to heat it, so that the flux is burned. It was possible to prevent sticking and shorten the solder connection time.

〔The invention's effect〕

As described above, according to the present invention, (a) local heating and cooling of the periphery thereof can be simultaneously performed by using a spray nozzle for heating and cooling, (b) heating gas and cooling It is possible to optimize the heating conditions and shorten the heating time by arbitrarily controlling the switching of the gas flow rate and the setting of the spraying timing. (C) The spraying nozzle and the metal mask basically have a simple mechanism, and The IC can be soldered in an inexpensive way.

[Brief description of drawings]

FIG. 1 (a) is a sectional view of an essential part of an embodiment of the present invention, and FIG. 1 (b) is a time chart of spraying an inert gas at high temperature and low temperature. 1 ... Liquid crystal display element, 2 ... LSI chip, 2a ... Flux, 3a ... Metal mask (top), 3b ... Metal mask (bottom), 4a ... Heating nozzle (top), 4b ... … Cooling nozzle (top), 4c …… Heating nozzle (bottom), 4d …… Cooling nozzle (bottom), 5a, 5b …… Temperature regulator, 6a, 6b …… Flow regulator, 7 …… Pulse controller , 8 ... Platen,
A: heating timing, B: cooling timing.

Claims (2)

[Claims] 1. A method of soldering an IC on a glass substrate having a wiring pattern, wherein first and second nozzles for spraying an inert gas for heating are provided on both front and back surfaces of the glass substrate, and an inert gas. A mask having a gas spray hole is provided, and the inert gas for heating is sprayed onto the solder connection part by the first nozzle at the same time as being sprayed on the back surface of the solder connection part by the second nozzle. By active gas flow
IC mounting method. 2. Third and fourth nozzles for spraying a cooling inert gas are provided on both front and back sides of the glass substrate, and the heating inert gas is soldered by the first and second nozzles. At the same time of spraying the cooling inert gas onto the glass substrate with the third and fourth nozzles, and with the cooling inert gas with the third and fourth nozzles. A second step of spraying the solder connection portion, wherein the flow rates of the cooling inert gas and the heating inert gas are changed in the first step and the second step. According to the inert gas flow described in item 1.
IC mounting method.