Thermal head and manufacturing method thereof
A method for manufacturing a thermal head is provided which includes the steps of forming a resistor layer and an insulating barrier layer, patterning the above two layers to form aligned heating resistors, forming a solid electrode layer over the heating resistors and the like, and partly removing the solid electrode layer to form opening portions and electrode layers for supplying electricity to the heating resistors. In the patterning step, part of the resistor layer and part of the insulating barrier layer, which are outside a heat generating area, are simultaneously removed to form the heating resistors having a planar U shape composed of a pair of effective heating portions and a connection portion connecting the above pair, the effective heating portions and the connection portion each having a predetermined length and width. The length of the connection portion is set to 5 μm or less.
1. A thermal head comprising:
a resistor layer generating heat when electricity is supplied thereto;
an insulating barrier layer covering the surface of the resistor layer so as to determine a planar size of a heat generating area; and
an electrode layer which is overlaid on the insulating barrier layer and which supplies electricity to the resistor layer,
wherein the resistor layer and the insulating barrier layer each have a planar U shape,
the resistor layer is present only under the insulating barrier layer and includes a pair of effective heating portions each having a predetermined length dimension and a predetermined width dimension and a connection portion connecting the pair of effective heating portions at an end thereof, and
the electrode layer includes a separate electrode and a common electrode, which are connected to said pair of effective heating portions at one end side of the resistor layer in the longitudinal direction, and also includes a folded electrode connected to said pair of effective heating portions and the connection portion at the other end side of the resistor layer in the longitudinal direction.
2. The thermal head according to claim 1 , wherein the connection portion of the resistor layer has a length dimension of 5 μm or less.
3. The thermal head according to claim 1 , wherein two end surfaces of the resistor layer in the longitudinal direction are each a tapered surface along which the thickness of the resistor layer is decreased toward the end side.
4. The thermal head according to claim 1 , wherein the folded electrode has a planar U shape and includes a pair of parallel electrode portions, which is parallel to the pair of effective heating portions of the heating resistor and which extends onto the insulating barrier layer, and a connection electrode portion which connects edges of said pair of parallel electrode portions on the insulating barrier layer, the edges being located at the resistor layer side.
5. A method for manufacturing a thermal head, comprising the steps of:
sequentially forming a solid resistor layer and a solid insulating barrier layer over an entire surface of a heat storage layer;
patterning the solid resistor layer and the solid insulating barrier layer to form at least one resistor layer and at least one insulating barrier layer, respectively, each having a planar U shape;
forming a solid electrode layer over the insulating barrier layer and the heat storage layer; and
removing part of the solid electrode layer to form at least one opening portion through which the insulating barrier layer is exposed and to form electrode layers overlaid on the insulating barrier layer at one side and the other side of the opening portion for supplying electricity to the resistor layer,
wherein, in the patterning step, part of the solid resistor layer and part of the solid insulating barrier layer, which are outside a heat generating area, are simultaneously removed so as to simultaneously determine the width dimensions and the length dimensions of the resistor layer and the insulating barrier layer.
6. The method for manufacturing a thermal head, according to claim 5 ,
wherein the resistor layer has a U shape and includes a pair of effective heating portions each having a predetermined width dimension and a predetermined length dimension and a connection portion connecting said pair of effective heating portions at an end thereof, and
the length dimension of the connection portion is set to 5 μm or less.
7. The method for manufacturing a thermal head, according to claim 5 ,
wherein, in the patterning step, two end surfaces of the resistor layer in the longitudinal direction are each formed to be a tapered surface along which the thickness of the resistor layer is decreased toward the end side.
8. The method for manufacturing a thermal head, according to claim 5 ,
wherein, in the step of patterning the solid resistor layer and the solid insulating barrier layer, part of the solid resistor layer and part of the solid insulating barrier layer, which are outside a heating area, are simultaneously removed by dry etching.
9. The method for manufacturing a thermal head, according to claim 5 ,
wherein the electrode layers include at least one separate electrode and at least one common electrode, which are connected to said pair of effective heating portions at one end side of the resistor layer in the longitudinal direction, and also include at least one folded electrode connected to said pair of effective heating portions and the connection portions at the other end side of the resistor layer in the longitudinal direction, and
the folded electrode has a planar U shape and includes a pair of parallel conductive portions, which is parallel to said pair of effective heating portions of the heating resistor and which extends onto the insulating barrier layer, and an electrode which connect said pair of parallel conductive portions at least on the insulating barrier layer.