Aluminum heat sink for a solid state relay having ultrasonically welded copper foil
First Claim
1. A method for making a solid state relay, the method comprising the steps of:
- (a) welding ultrasonically a copper foil to a heat sink;
(b) soldering a substrate to said copper foil; and
(c) soldering an output switching element to said substrate;
wherein said copper foil increases solder coverage between said heat sink and said substrate, improving a heat transfer from said output switching element to said heat sink.
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Accused Products
Abstract
Instead of soldering a circuit board or substrate to a nickel-plated aluminum heat sink for solid state relay applications, the present invention utilizes ultrasonic welding to weld a copper foil to a non-nickel-plated aluminum heat sink. The circuit board or substrate is subsequently soldered to the copper foil. The superior solderability of copper foil brings increased solder coverage between the heat sink and substrate, improving the heat transfer from the output switching element to the heat sink. This method eliminates the need for fixturing since the copper foil is surrounded by non-nickel-plated aluminum that is non-solderable by commonly used solders. This method also eliminates the high costs associated with nickel-plating and hazardous waste disposal, since no chemical wastes are produced. With this method, the same size solid state relay is now able to carry more current due to the better heat transfer and heat dissipation capabilities.
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Citations
16 Claims
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1. A method for making a solid state relay, the method comprising the steps of:
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(a) welding ultrasonically a copper foil to a heat sink;
(b) soldering a substrate to said copper foil; and
(c) soldering an output switching element to said substrate;
wherein said copper foil increases solder coverage between said heat sink and said substrate, improving a heat transfer from said output switching element to said heat sink. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A solid state relay comprising:
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a heat sink;
a copper foil ultrasonically welded to said heat sink;
a substrate soldered to said copper foil; and
an output switching element soldered to said substrate;
wherein said copper foil increases solder coverage between said heat sink and said substrate, improving a heat transfer from said output switching element to said heat sink. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification