Metal fusion bonding – Process – With protecting of work or filler or applying flux
Reexamination Certificate
2000-03-08
2002-05-07
Elve, M. Alexandra (Department: 1725)
Metal fusion bonding
Process
With protecting of work or filler or applying flux
C228S120000, C228S232000, C228S234100
Reexamination Certificate
active
06382502
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention concerns a method of manufacturing a heat sink made of aluminum in which a plurality of fins are brazed on a heat dissipating substrate.
2. Related Art Statement
In electronic equipments such as computers and NC control equipments, many heat generating devices are incorporated and various kinds of heat dissipating members are used in order to rapidly release the generated heat and maintain the normal operation for a long time. A heat sink made of aluminum in which a plurality of thin plate-like fins are attached on a heat dissipating substrate is one of such heat dissipating members. Further, in view of the material, 1000 series aluminum excellent particularly in thermal conductivity is often used and 3000 series or 5000 series aluminum is used in the case of requiring high strength.
Further, in the heat sink of the shape described above, it is important to enlarge the heat dissipating area in order to improve the heat dissipating performance and, for this purpose, it is necessary to reduce the thickness of the fins and narrow the distance between the fins thereby increase the number of fins.
However, since 3000 series or 5000 series aluminum is inferior in the thermal conductivity to 1000 series aluminum, heat sinks in which fins of a reduced thickness are formed of such materials for ensuring the strength involve a problem in the heat dissipating performance. Further, when the fins of reduced thickness are formed of 1000 series aluminum having good thermal conductivity, they result in a problem that they are liable to be broken by vibrations or impacts upon handling.
SUMMARY OF THE INVENTION
An object of this invention is to provide a method of manufacturing a heat sink made of aluminum having both high strength and heat dissipating performance together in view of the back ground art as described above.
For attaining the foregoing object, this invention provides a method of manufacturing a heat sink made of aluminum by brazing a plurality of fins
13
on a heat dissipating substrate
11
, in which the fin
13
comprises an Al—Mg—Si series alloy containing from 0.3 to 0.7% by weight of Mg, from 0.3 to 0.7% by weight of Si and the balance of Al and inevitable impurities, cooling is conducted in a cooling process after heating for brazing at a rate of 50° C./min or higher in a range from 450-500° C. to 300° C. and then artificial aging is applied at 100 to 250° C.
The Mg content in the Al—Mg—Si series alloy constituting the fin
13
is preferably from 0.4 to 0.6% by weight.
The Si content in the Al—Mg—Si series alloy constituting the fin
13
is preferably from 0.4 to 0.6% by weight.
Further, cooling after the heating for brazing is preferably conducted at a rate of 75° C./min or higher.
Further, the artificial aging is applied preferably at 160 to 220° C.
Further, brazing between the heat dissipating substrate
11
and a plurality of fins
13
are preferably conducted by using an Al—Si series alloy brazing material and a chloride series flux in an inert gas atmosphere while heating at 577 to 610° C.
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patent: 5810949 (1998-09-01), Chakrabarti et al.
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patent: 5894054 (1999-04-01), Paruchuri et al.
patent: 6120848 (2000-09-01), Van Evans et al.
patent: 357122551 (1982-07-01), None
Fukui Koichiro
Tsukuda Ichizo
Ushioda Shunta
Elve M. Alexandra
Pittman Zidia
Showa Denko K.K.
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