Metal fusion bonding – Process – Specific mode of heating or applying pressure
Patent
1996-05-07
1997-12-30
Heinrich, Samuel M.
Metal fusion bonding
Process
Specific mode of heating or applying pressure
228264, 228 13, 228 495, B23K 1015, B23K 1018, B23K 300
Patent
active
057020515
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a device (manipulator) for moving an object by means of thermal change in shape or volume, such that the object is moved when a predetermined process temperature has been reached. Especially in heating furnaces a manipulator system is needed which allows moving a body towards or away from another body when a predetermined temperature has been reached. Usually, complicated devices are necessary to ensure a safe handling of the bodies, particularly in the case of higher temperatures.
An example of this are soldered joints in the field of electronics. Due to the present-day miniaturization of the components and the sensitivity of materials for printed circuit boards, it becomes more and more difficult to unsolder defective or wrongly inserted components from a printed circuit board. There is always a risk of damaging the printed circuit board or the component.
When repairing components, more or less complicated devices are used whose quality is often poor. This involves high costs and damage to circuit modules is inevitable. In the prior art, the following repair soldering methods are generally used:
The vapor-phase unsoldering has considerable advantages. However, this method also requires relatively complicated devices for lifting off the components. The main problem is the time of the unsoldering. In order to prevent both the conductor lines and the component from being damaged, the pulling force must only act on the component after the solder is molten.
Irrespective of the unsoldering method selected, there is always the problem that the solder must be molten at all joints between the component and the printed circuit board in order to prevent damage to the conductor lines or to the component.
There is no system which is, one the one hand, capable of entering and passing through the heating furnace and, on the other hand, removes the component automatically only when the solder is molten.
The object to be achieved by the invention is to provide a device which can particularly be used for unsoldering electronic components, which is easy to handle, works reliably and does not cause damage to the circuit module or the component. Preferably, the device should be so small that it can for instance be directly placed on a printed circuit board, connected with a component to be unsoldered and removes the component from the printed circuit board when a predetermined temperature has been reached.
This object is achieved with the features of the claims.
The solution of the invention is based on the concept to provide a device in which a temperature-dependent change in shape or volume occurs and which is connected with an object to be moved, for instance a component on a printed circuit board. When a predetermined temperature has been reached, the change in shape or volume causes the object to move. The device can consist of a bimetal, a metal having a shape memory effect, bellows or a piston-equipped cylinder filled with a fluid (liquid and/or gas) or solid bodies which expand when the temperature increases.
The advantage of the invention lies in a temperature-controlled movement of an object with a high-level precision which is solely caused by the process temperature inside the heat treatment means without any additional action from the outside.
In the following, the invention is described in more detail with reference to the single drawing.
FIG. 1 shows a basic illustration of an embodiment according to the invention.
FIG. 1 shows an embodiment according to the invention wherein the change in volume of a fluid or solid body is used in a cylinder which is sealed by a piston 2 movable in said cylinder. Rods 3 are hinged in a holding device 5 at the cylinder 1, rest on the piston 2 and are connected with an object 4. Due to the change in volume of the interior of the cylinder when a predetermined temperature has been reached, the piston 2 moves upwards from an initial position A together with the rods 3. Due to this, the object 4 (e.g. a component) is lifted off a base (e.g. a printe
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"ERSA EAS 1000, Leistungsstarkes Auslotsystem fur integrierte Schaltkreise", Wertheim, Nov. 1987.
Heinrich Samuel M.
Rauchfuss, Jr. George W.
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