Lapping machine

A lapping machine includes upper and lower lapping wheels and a sprocket having a common centered rotational axis. A rotational drive source for at least one of the upper and lower lapping wheels provides rotational movement about the axis. At least two independently locatable gears or sprockets disposed radially exterior of the upper and lower lapping wheels rotatably carry a carrier between the upper and lower lapping wheels, in which a material carried within an opening formed in the carrier travels at least partially radially exterior of both lower and upper lapping wheels during operation of the machine.

FIELD OF THE INVENTION

The present invention relates generally to lapping machines and, more particularly, to lapping machines capable of accommodating differently sized carriers.

BACKGROUND OF THE INVENTION

Lapping machines, such as lapping machine10shown inFIG. 1, typically include at least a ring sprocket16having a lower lapping wheel128and a center sprocket12. The ring sprocket16has a radius18and center sprocket12has a radius14. During operation of lapping machine10, center sprocket12rotates about a center axis24. Teeth of a carrier20mesh with the teeth of ring sprocket16and the teeth of center sprocket12so that carrier20is urged into simultaneous rotational movement about its center axis26and planetary movement between radius14and radius18. Carrier20includes one or more openings22for carrying a work piece28, such as a disk that is exposed to lower lapping wheel128during operation. The diameter30of carrier20is a fixed distance, equal to the difference between radius18of ring sprocket16and radius14of center sprocket12. As a result, if a carrier20having a diameter greater than diameter30is desired, it would be necessary to replace at least one of the center sprocket12and ring sprocket16, which is a costly proposition. In addition, with the construction of lapping machine10, it is similarly apparent that the maximum size of a disk work piece28must be less than diameter30.

Such known machines suffer from the drawback that to accommodate a larger size carrier, the machine must be significantly enlarged, taking up a similarly increased amount of space in a manufacturing facility, thereby reducing production efficiencies. In addition, storage provisions must be made to store differently sized lapping wheel not in use. Further, in the event larger carriers, even only incrementally larger carriers, can be used for applications previously unknown, these machines lack the flexibility to accommodate the marginally larger carrier, unless further sizable investment in a larger lapping wheel is made.

What is needed is a lapping machine that can accommodate differently sized carriers, and further, can accommodate carriers, and even work pieces, having a dimension greater than the difference between the radius of the ring sprocket and the radius of the center sprocket.

SUMMARY OF THE INVENTION

The present invention relates to a lapping machine including upper and lower lapping wheels and a sprocket having a common centered rotational axis. A rotational drive source for at least one of the upper and lower lapping wheels provides rotational movement about the axis. At least two independently locatable gears or sprockets disposed radially exterior of the upper and lower lapping wheels rotatably carry a carrier between the upper and lower lapping wheels. A material carried within an opening formed in the carrier travels at least partially radially exterior of both lower and upper lapping wheels during operation of the machine.

The present invention further relates to a lapping machine including upper and lower lapping wheels and a sprocket having a common centered axis. A rotational drive source for at least one of the upper and lower lapping wheels provides rotational movement about the axis. At least two independently locatable gears or sprockets are disposed radially exterior of the upper and lower lapping wheels for rotatably carrying a carrier between the upper and lower lapping wheels, in which a work piece composed of a semiconductor material or rigid material carried within an opening formed in the carrier travels at least partially radially exterior of both lower and upper lapping wheels during operation of the machine.

The present invention yet further relates to a lapping machine including upper and lower lapping wheels and a sprocket having a common centered axis. A rotational drive source for at least one of the upper and lower lapping wheels provides rotational movement about the axis. At least two independently locatable idler gears or sprockets are disposed radially exterior of the upper and lower lapping wheels for rotatably carrying a carrier between the upper and lower lapping wheels. The carrier travels at least partially radially exterior of both lower and upper lapping wheels during operation of the machine.

An advantage of the present invention is it can accommodate differently sized carriers.

A further advantage of the present invention is that it can accommodate work pieces larger than the difference between the radii of the center sprocket and the ring sprocket.

A still further advantage of the present invention is that it can accommodate larger work pieces without significantly increasing the footprint of the lapping machine, as compared to prior art lapping machines.

A yet further advantage of the present invention is that it can reduce the number of operating cycles required to produce a predetermined amount of surface area of work pieces.

A still yet further advantage of the present invention is that it can accommodate customized carrier sizes for more efficient manufacturing operations.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIGS. 2-4, a lapping machine100(FIG. 2) according to the present invention includes an upper portion104that is supported above a lower portion102by support columns106. As shown, an annular base108extends outwardly from lower portion102toward upper portion104and encloses a lower lapping wheel128(FIG. 2) and a center sprocket122(FIG. 2). An upper lapping wheel116extends toward lower lapping wheel128, upper lapping wheel116being rotatably carried by shaft118about an axis120and selectively raised and lowered with respect to lower lapping wheel128. In one embodiment, center sprocket122, upper lapping wheel116and lower lapping wheel128are centered with respect to axis120. Controller110controls the operations of lapping machine100and includes a display device112and input device114. Drive devices (not shown) contained within upper portion104and lower portion102urge upper lapping wheel116, lower lapping wheel128and center sprocket122into an appropriate combination of rotational/translational movement required for efficient operation of lapping machine100. That is, one or both of upper and lower lapping wheels116,128can rotate, either in the same or opposite directions, and center sprocket122can also rotate, if desired. In addition, upper and lower lapping wheels116,128can be selectively directed toward and away from each other during operation of lapping machine100. As will be discussed in further detail below, lapping machine100can accommodate differently sized carriers144(FIG. 3).

In one embodiment, center sprocket122includes teeth124disposed along its periphery, center sprocket122having a radius126for meshing with corresponding teeth125of a carrier144. As shown inFIG. 3, radius126of center sprocket122is less than an inner radius130of lower lapping wheel128, with both sprocket122and lower lapping wheel128concentrically centered along axis120. Lower lapping wheel128has an outer radius132. Abrasive material (not shown) is disposed along the surface of upper lapping wheel116between inner and outer radii130and132. In one embodiment, the inner and outer radii of the upper and lower lapping wheels116,128are substantially the same.

As further shown inFIG. 3, gear or idler sprocket134is rotatably carried about an axis136and a gear or idler sprocket138is rotatably carried about an axis140, each axis formed in cradle142so that cradle142rotatably carries idler sprockets134,138. Although not shown inFIG. 3, cradle142can contain independently positionable idler sprockets134,138to be rotatably carried about parallel axes along different positions of cradle142. In another embodiment, cradle142is not used, with additional axes (not shown) formed in lower portion102. In one embodiment, idler sprocket134includes teeth156peripherally disposed along a radius158for meshing with teeth125of carrier144. Similarly, idler sprocket138includes teeth160peripherally disposed along a radius162for meshing with teeth125of carrier144. That is, carrier144is rotatably carried by virtue of teeth156,160,124of respective idler sprockets134,138and center sprocket122meshing with teeth125of carrier144. In one embodiment, idler sprockets134,138are not directly associated with driving sources of lower portion102(FIG. 1), so that sprockets134,138do not rotatably drive carrier144. In another embodiment, sprockets134,138are idler gears.

Referring toFIGS. 3 and 4, carrier144having a diameter146includes an opening148that is configured to carry a work piece150, such as a semiconductor material constructed of silicon, silicon carbide, glass, quartz, metal or ceramic or a combination thereof. However, it is to be understood that semiconductor materials can also be constructed of or include other materials. Further, it is to be understood that work pieces, which are constructed of other suitable rigid materials, can also be used. As shown, carrier144includes one opening148, but it is to be understood that carrier144can include more than one opening148, each configured to carry a work piece150. In one embodiment, opening148is eccentrically disposed with respect to the center166of carrier144. As shown inFIG. 3, work piece150has a diameter164that is greater than the difference between inner and outer radii130and132of lower lapping wheel128. In this embodiment, work piece150has an overhang152that extends outside of outer radius132of lower lapping wheel128. Similarly, carrier144has an overhang154that extends outside of outer radius132of lower lapping wheel128.

Overhang152as shown inFIG. 3represents a minimum overhang152, and thatFIG. 4represents a maximum overhang152, as carrier144is rotated about its center166, 180 degrees with respect toFIG. 3. The minimum and maximum overhangs152correspond with the minimum and maximum extreme positions of work piece150with respect to radius132of lower lapping wheel128due to eccentricity of opening148, as is appreciated by those skilled in the art. In one embodiment, it is possible to have a maximum overhang of the work piece150that is about 33% of the surface area of one side of the work piece150. However, depending upon the operating parameters of lapping machine100, including work piece material type, rotational speeds, the amount of compressive forces applied to opposite surfaces of work piece150by upper and lower lapping wheels116,128, and the shape of work piece150, it may be possible to increase the previously identified maximum overhang152.

Lapping machine100can accommodate carriers144of increased diameter by virtue of locating idler sprockets134,138further outwardly of radius132, the resulting increase in footprint of lapping machine100is minimally increased, if increased at all, compared with prior art lapping machine10(seeFIG. 1) in which an increase of radius18of ring sprocket16is required to accommodate carrier20. In addition, with the ability to selectively locate idler sprockets134,138, lapping machine100provides flexibility and adaptability to seamlessly accommodate a wide range of carriers144and corresponding work pieces150. It is also to be understood that more than one set of idler sprockets134,138can be used with lapping machine100, permitting operation with a plurality of differently sized carriers144and corresponding work pieces150. Therefore, not only can lapping machine100accommodate larger carriers144and work pieces150than is possible for similarly sized lapping wheels of prior art lapping machine10, lapping machine100can simultaneously accommodate differently sized, smaller carriers144capable of more quickly and efficiently producing work pieces than previously possible.

It is to be understood that although an overhang152is always present during operation of lapping machine100as shown inFIGS. 3,4, the relative sizing of carrier144, opening(s)148and work piece150dictate the existence of and/or extent of overhang152.

It is also to be understood that although center sprocket122and idler sprockets134,138can be formed of unitary construction, i.e., that teeth124,156,160are formed by machining a solid disk of material (spur gear design), in another embodiment, teeth124,156,160can be formed by pins disposed along the periphery so that the pins become the teeth of sprocket122and gears134,138. That is, the pins can be affixed at a desired radius substantially perpendicular to the respective sprocket122,134,138.

FIGS. 5,6shows an embodiment of lapping machine100which is otherwise similar toFIGS. 3,4, except that carrier144and center sprocket122are sized differently, idler sprockets134,138are thus located at different respective axes168,170, and cradle142is configured to receive differently sized carriers. It is to be understood that idler sprockets134,138can be positioned at even different axis positions and that gears134,138are not necessarily the same diameter. It is also to be understood that the lapping machine can be configured for use without a cradle, making use of hole patterns formed in the lower portion102to receive and secure the idler sprockets to the lower portion102.

It is to be understood that lapping machine100can be used without work pieces150installed in carriers144. That is, in one embodiment, no work piece150is placed in any of the carriers144, so that carriers144are exposed to upper and lower lapping wheel116,128during operation of lapping machine100.