Solder cleaning system

Abstract

A method of cleaning solder from the jaws of a solder ball test device including the steps of heating a gas to a temperature above the melting temperature of the solder and directing the heated has over the jaws of a solder ball test device to remove solder from the jaws, and an apparatus for carrying out the method.

Claims

1. An automatic cleaning station for cleaning solder from jaws of a solder ball test device, the cleaning station comprising a cleaning system, and the cleaning system comprising: a heat exchanger and a body enclosing the heat exchanger such that a volume is enclosed between the body and the heat exchanger; and an inlet to the volume and an outlet nozzle in fluid communication with the volume; wherein, in use, gas under pressure introduced to the volume is heated by the heat exchanger such that heated gas is delivered through the nozzle; wherein the automatic cleaning station is mounted on the solder ball test device; and wherein the solder ball test device is configured to move and to rotate the jaws in the heated gas.

2. The automatic cleaning station according to claim 1, wherein the heat exchanger comprises an electrical heater cartridge.

3. The automatic cleaning station according to claim 1, wherein the outlet nozzle has a bore diameter between 0.5 mm and 1.5 mm.

4. The automatic cleaning station according to claim 1, wherein the pressure of the heated gas at an exit from the nozzle is between 2 and 5 bar.

5. The automatic cleaning station according to claim 1, wherein the heat exchanger is adapted to heat the gas to a temperature between 200 degrees Centigrade and 500 degrees Centigrade.

6. The automatic cleaning station according to claim 1, further comprising a temperature sensor.

7. The automatic cleaning station according to claim 1, further comprising a heat guard adapted to protect a user.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Features of the invention will be apparent from the following description of a preferred embodiment described with reference to the accompanying drawings in which:

(2) FIG. 1 shows a schematic representation of a typical solder ball ready to be tested before it has been gripped by the jaws;

(3) FIG. 2 shows a schematic representation similar to FIG. 1 but where the jaws have a build-up of solder in the cavity;

(4) FIG. 3 shows schematic representation of a cleaning system that removes the build-up of solder from the jaws; and

(5) FIG. 4 shows a representation similar to FIG. 3 in more detail of a preferred embodiment.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 1 illustrates typical jaws 8 of a solder ball test device. Each jaw 8 includes a cavity 11 that close around a solder ball 10 and reform it to the cavity shape. This reforming of the solder ball 10 enables the optimum grip.

(7) FIG. 2 illustrates a similar pair of jaws 8 with a build-up of solder 12 within the cavity 11 that affects the reforming of the solder ball 10, reducing the maximum possible pull force.

(8) FIG. 3 illustrates a schematic representation of one embodiment of the invention. A heater 1 is located in a heat exchanger 2 and is used to raise the temperature of the heat exchanger 2 to a value above the melting point of the solder ball 10. The melting temperature of solders varies between around 150 C. to 250 C. The heat exchanger 2 would typically be raised to a temperature of between 200 C. to 500 C. It is important that the materials used in the construction of the invention can withstand the temperatures that they will be exposed to. The heat exchanger 2 can, for example, be a plain cylinder but in a preferred embodiment it would have fins 3 to increase its surface area. The heat exchanger 2 is enclosed in a body or casing 4 such that air, or any other gas 5, can be pumped into a volume 13 enclosed between the body 4 and the heat exchanger 2.

(9) FIG. 4 illustrates a round cylindrical design mounted upon a support 9. Other embodiments of the invention may be based on square cylinders, rectangular cylinders or flat heat exchangers with the fins and or heat exchange surface on only one or more sides.

(10) Under the pressure generated by a pump, a pressurised storage cylinder or other such means, gas flows into the volume 13 through an inlet 14 and over the heat exchanger 2. The temperature of the gas 5 is raised above that of the melting point of solder. The heated gas 5 then exits out of a nozzle 6 of the body 4. The gas exiting out of the nozzle is subsequently used to melt the solder in the cavities 11 of the jaws 8. The velocity of the gas 5 assists in moving the melted solder out of the cavities and away from the jaws 8.

(11) The jaws 8 to be cleaned are only slightly larger than the solder balls 10, typically less than 1 mm. To melt the solder in the cavities 11 the diameter of the heated gas jet does not need to be large; the nozzle 6 bore diameter may typically be between 0.5 to 1.5 mm. The jet though does need to have a relatively high velocity. The total pressure at exit from the nozzle 6 may thus be in the region of 2 to 5 bar.

(12) In a preferred embodiment, the heater 1 is an electrical heater cartridge with its temperature being controlled by a temperature sensor placed in close proximity to it; for example in a hole or aperture 7 extending through the body 4 and into the heat exchanger 2.

(13) In preferred embodiments, the heat exchanger 2 is made from a material with a relatively high heat conductivity whereas the body 4 and support 9 would be preferably, but not exclusively, be made from a material with lower heat conductivity. In a preferred embodiment the assembly would be mounted within a heat guard to protect operators from the hot gas and components. The guard would have a hole in it allowing the jaws 8 to be placed into the hot gas jet for cleaning. The guard may also include a box that the molten solder removed from the jaws 8 is captured in for safe disposal.

(14) Effective cleaning of the cavities 11 requires the jaws 8 to be moved and rotated in the hot gas jet. This can be done manually or by mounting the cleaning system on the same machine that the jaws 8 are used on thereby providing an automatic cleaning station.