This invention relates to a fin structure and, more particularly, to a heat-dissipating fin structure to be assembled for heat dissipation and the assembly thereof. 
When using electronic products, the heat produced therefrom is usually removed by a heat sink, and the operating efficiency of the electronic products is thereby increased and prevented from damaging.  For example, the central processing unit (CPU) of a computer system may be provided with a high-density heat-dissipating fin assembly on it. 
Usually, the heat from a heat source is transferred to a heat sink and then taken away by heat convection.  In this case, a heat sink must have a large area for improving the heat convection effect and further raising the heat dissipating efficiency.  Accordingly, it is preferable to maximize the number of the fins on a substrate for the high-density heat-dissipating fin assembly. 
Up to now, however, the fabricating techniques for fins and the limitations on fastening and assembling fins have prevented the space between two adjacent fins from being further reduced.  Therefore, it is difficult to achieve a maximum fin number. 
For example, the published Taiwan patent No.  365411 has disclosed a heat-dissipating fin assembly composed of a front fin, a rear fin, and a plurality of middle fins.  In this case, since the space between any two adjacent fins is determined by the thickness of an extra concave portion on the fin, the space cannot be reduced as desired. 
Still an example, the published Taiwan Patent No.  506247 has disclosed a heat sink composed of a plurality of high-density heat-dissipating fins.  In this case, since the plurality of fins are assembled by employing hooks and grooves provided thereon, the space between any two adjacent fins still can not be effectively reduced due to the hook length required to assemble the fins. 
According to the above-mentioned drawbacks of the conventional fin assemblies, the invention provides a fin structure being capable of minimizing the space between two adjacent fins in an assembly.  Thus, the number of the fins on a substrate can be effectively increased and the heat-dissipating efficiency of a heat sink can be improved. 
To solve the above-mentioned problems, one object of the invention is to provide a fin structure to minimize the space of two adjacent fins in an assembly. 
Another object of the invention is to provide a fin structure to maximize the number of the fins of a fin assembly. 
In one aspect of the invention, the invented fin structure includes a first concavo-convex portion and a second concavo-convex portion.  The first concavo-convex portion is formed with a concave on a first surface of the fin in the direction of thickness, and a corresponding convex on a second surface of the fin in the direction of thickness.  The second concavo-convex portion is formed with a first concave and a second concave on the first surface of the fin in the direction of thickness, and a corresponding first convex and a corresponding second convex on the second surface of the fin in the direction of thickness.  Wherein, the first concavo-convex portion and the second concavo-convex portion are symmetrical with respect to a center of the fin, and the second convex of the second concavo-convex portion can be exactly received by the concave of the first concavo-convex portion. 
In another aspect of the invention, the fin structure of the invention further includes a plurality of protruding sheets provided on two sides of the fin.  In addition, one fin is clasped and mounted with another fin by riveting the concave of the first concavo-convex portion on one fin and the second convex of the second concavo-convex portion on another fin and by bending the protruding sheets. 
The invention discloses a fin assembly assembled by clasping a plurality of fins.  Each of the fins has a characterization the same as the above described fin structure. 
To be emphasized in this aspect is that the first convex of the second concavo-convex portion has a height equaling to a space between two adjacent fins.  In addition, the protruding sheets are bent in a cross manner. 
The invention has the following advantages.  First, the formation of the concavo-convex portions are easy to control, therefore, a minimum space between two adjacent fins can be achieved.  Secondly, it is convenient to clasp the concavo-convex portions and the protruding sheets, and the assembled assembly would not depart easily.  Thirdly, the invention uses only one fin structure and therefore enables a more simplified and effective assembly.  Fourthly, the fin structure designed in the invention is appropriate for formations of common aluminum and copper materials.