JPH0482060B2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention forms a minute heat pipe (i.e., micro heat pipe) inside the substrate for integrated circuits such as ICs and hybrid ICs in order to improve its thermal conductivity. The present invention relates to a method of injecting a condensable fluid as a working fluid into a micro hermetically sealed hollow part that becomes a micro heat pipe.

BACKGROUND TECHNOLOGY As is well known, this type of integrated circuit is one in which a circuit including a large number of elements such as transistors and diodes is formed on the surface of a ceramic substrate such as silicon by methods such as photo-etching, diffusion, and vapor deposition. It has excellent advantages such as small size, high reliability, and low cost. However, since integrated circuits are constructed in a sealed package, their output is limited by heat generation, and therefore high-power ICs
and hybrid ICs, heat dissipation is achieved by attaching heat dissipation fins to the package, or forced ventilation is performed while mounted on the printed circuit board to promote cooling.

However, the above-mentioned cooling means are intended to promote heat exchange with the outside when sealed in a package, but since the heat source is a circuit formed on a ceramic substrate, heat radiation from that circuit is necessary. Efficient cooling cannot be achieved unless heat is actively transferred to the heat dissipation portion to the outside, such as the fins. Conventionally, this point has not been particularly considered, and there is still room for improvement in achieving higher output and higher functionality of integrated circuits.

Against this background, it has been conventionally considered to form a minute heat pipe inside a substrate for an integrated circuit to improve the thermal conductivity of the substrate itself. This is a structure in which, for example, a thin groove is formed inside a silicon substrate, the narrow groove is sealed with Pyrex glass or a silicon plate, and only a condensable fluid such as water is sealed in the airtight hollow space thus formed. The condensable fluid repeatedly evaporates and condenses while circulating in the hollow space, transporting heat as its latent heat, and as a result, the substantial thermal conductivity of the entire substrate is improved. It is.

To form the above-mentioned so-called micro heat pipe, the conventional method for injecting a condensable fluid into the hollow portion is to place the entire substrate with narrow grooves in a predetermined container, and then evacuate the inside of the container so that the condensable fluid is injected into the hollow portion. After exhausting the condensable gas, the vapor of the condensable fluid is sent into the inside of the container, and while maintaining this state, a silicon plate or the like is attached to the surface of the substrate to seal the narrow groove. A method has been considered in which a condensable fluid is injected into the hollow part through a capillary tube after the hollow part is sealed.

Problems to be Solved by the Invention However, the method of sealing a thin groove formed in a substrate to form a hollow part and then injecting a condensable fluid into the hollow part does not require the use of a vacuum atmosphere or a condensable fluid atmosphere. However, since the condensable fluid must be injected into the hollow space through a capillary tube with a diameter of several tens to hundreds of μm, the condensability of the liquid phase may be reduced. If the fluid is simply poured into the tube, the condensable fluid will clog the capillary due to surface tension, making it impossible to quickly inject the fluid.

This invention has been made in view of the above circumstances, and it is an object of the present invention to provide a micro heat pipe injection method that can reliably and quickly inject condensable fluid through a capillary tube. .

Means for Solving the Problems In order to achieve the above object, the present invention forms, in a substrate for an integrated circuit, a micro hermetically sealed hollow portion having a micro-width recess inside which generates capillary pressure. After the non-condensable gas is evacuated from the hollow part, a condensable fluid is sealed as a working fluid to form a micro heat pipe, and after the non-condensable gas is evacuated through a capillary tube communicated with the hollow part, The method is characterized in that the condensable fluid vapor is sent into the hollow part through the capillary tube, and the condensable fluid vapor is condensed and liquefied within the hollow part.

In other words, in the method of the present invention, a non-condensable gas is evacuated and a condensable fluid is injected through a thin capillary tube of several tens of micrometers to several hundred micrometers. Since the condensable fluid vapor is sent in a vapor state and the condensable fluid vapor is condensed and liquefied inside the hollow part, the condensable fluid does not become clogged in the middle of the capillary, and therefore the required amount of condensable fluid can be reliably and liquefied. It can be quickly injected into the hollow space.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic diagram of an apparatus for carrying out the method of the present invention, in which an integrated circuit is formed on a substrate 1. A capillary tube 3 having a diameter of several tens of μm to several hundred μm is connected to the hollow part 2, which is a micro heat pipe. The first valve 4 is connected to the exhaust device 5 and the first valve 4 is connected to the exhaust device 5.
Another valve (hereinafter referred to as the second
The heating container 7 is immersed in a heating medium 10 in a constant temperature bath 9. Here, the hollow part 2 is formed in advance by a VV on the substrate 1.
In addition to carving a character-shaped narrow groove, the substrate 1
The capillary tube 3 is made to communicate with the hollow part 2 by attaching a plate material such as Pyrex glass to the surface of the plate material and sealing the narrow groove, and by attaching the capillary tube 3 to the plate material in advance.

In order to inject the condensable fluid 6 into the hollow part 2 using the above-mentioned apparatus, first, the first valve 4 is opened, and the second valve 8 is closed, and the evacuation device 5 is driven so that the hollow part 2 is injected with the condensable fluid 6. The non-condensable gas is exhausted from the hollow part 2 to create a vacuum inside the hollow part 2. Then the first
Close the valve and open the second valve 8,
At the same time, the condensable fluid 6 in the heating container 7 is heated by the heating medium 1.
The substrate 1 is heated and evaporated by the temperature of 0, and then the substrate 1 is cooled. In this way, the condensable fluid 6 becomes vapor and passes through the inside of the capillary tube 3 into the hollow part 2 of the substrate 1.
The vapor then condenses and liquefies, so that a condensable fluid 6 is injected into the hollow part 2.
In that case, even if the capillary tube 3 is extremely thin, the condensable fluid 6 flows inside the capillary tube 3 in the form of vapor.
It flows smoothly to the hollow part 2, and no inconvenience such as clogging occurs on the way. In addition, although steam has a large volume, it is small as a liquid, so it is easy to inject a very small amount of liquid, and furthermore, by controlling the heating conditions, it is easy to make minute adjustments to the amount of liquid injected. be able to.

If the hollow part 3 is completely sealed by sealing and welding the capillary tube 3 near the surface of the substrate 1, the acute corner part in the hollow part 3 will act as a wick to generate capillary pressure. It becomes a micro heat pipe.

In the above explanation, the condensable fluid was injected immediately after the non-condensable gas was exhausted, but the condensable fluid vapor injection and vacuum evacuation were alternately performed multiple times to inject the non-condensable gas. It is also possible to perform exhaust even more thoroughly.

Effects of the Invention As is clear from the above description, in the method of the present invention, a minute hermetic hollow portion having a minute width recess that generates capillary pressure is formed in a substrate for an integrated circuit, and a non-condensable When forming a micro heat pipe by sealing a condensable fluid as a working fluid after evacuating the gas, the non-condensable gas is evacuated through a capillary tube communicated with the hollow part, and then the condensable fluid vapor is evacuated. Since the condensable fluid vapor is sent into the hollow part through the capillary tube and is condensed and liquefied within the hollow part, even if the liquid injection tube is a capillary tube with an extremely small inner diameter, there will be no clogging due to surface tension. , the condensable fluid can be reliably and quickly injected into the hollow part. Furthermore, since the method of the present invention is injected in the form of steam, it is easy to inject a very small amount, and by controlling the heating conditions for generating steam, it is easy to finely adjust the amount of injection. It also produces effects such as

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an apparatus used to carry out the method of the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Hollow part, 3... Capillary tube, 6... Condensable fluid.

Claims (1)

[Scope of Claims] 1. A micro airtight hollow part having a micro-width recess inside that generates capillary pressure is formed in a substrate for an integrated circuit, and after a non-condensable gas is exhausted from the hollow part, a condensable fluid is discharged. is sealed as a working fluid to form a micro heat pipe, the non-condensable gas is evacuated through a capillary tube communicated with the hollow section, and then the condensable fluid vapor is passed through the capillary tube into the hollow section. 1. A method for filling a micro heat pipe, characterized by feeding a liquid into a micro heat pipe, and condensing and liquefying a condensable fluid vapor within the hollow part of the heat pipe.