In this exemplary embodiment, the projection of the circular area and the circular contact electrode on the forming surface constitutes a structure with concentric circles. Thus, when the LED chip is soldered to the driving circuit, the solder is located at the center of the concentric circles. It can be ensured that there is a large area of contact between the driving circuit and the circular area of the second extension electrode 521, and between the circular area of the second extension electrode 521 and the circular contact electrode, thereby increasing the soldering strength.

It should be noted that, in other exemplary embodiments, the projection of the circular region and the circular contact electrode on the forming surface may also be in a structure with intersecting circles, inscribed circles or an inner circular.

As shown in FIG. 14, in this exemplary embodiment, the first contact electrode 506 is a circular primary contact electrode, the first extension electrode 511 covers the circular primary contact electrode, and a partial area (circular area) of the first extension electrode 511 is used to form the plurality of concave spots 530.

In this exemplary embodiment, the first extension electrode 511 is electrically insulated from the first extension electrode 521 by the second insulation layer 512.