Thin-film magnetic head

Abstract: A thin-film magnetic head (101) includes windings assembled from two levels (105, 106) having two electrically conducting layers (103, 104), each including a connecting track (107, 116) and a winding (110, 113). To reduce the electrical resistance, auxiliary tracks (130, 131) which are in contact with the connecting tracks and also form part of the said layers extend parallel to the connecting tracks. Consequently, no additional manufacturing steps are required.

Description: The invention relates to a thin-film magnetic head, having a substrate on which a magnetic head structure is provided comprising a flux conductor layer and two electrically conducting layers, which are each located one above the other at separate levels, which are partly located between the substrate and the flux conductor layer, the first layer including a first winding having a first through-connection end and a first connecting track having a first connecting end, and the second layer including a second winding having a second through-connection end, and a second connecting track having a second connecting end, the through-connection ends being interconnected and the connecting tracks being adjacent to each other. Such a structure is generally known for a thin-film writing head. For writing a signal, a current is sent through the winding via the connecting tracks. As the connecting tracks and the winding have a resistance, heat will develop. With the ruling tendency to increasingly smaller magnetic head dimensions. especially narrower magnetic heads, the dimensions of the windings and more specifically those of the connecting tracks also become smaller. As the resistance depends on the cross-section of the current conductors, in this case inter alia the connecting tracks, the resistance and consequently the heat developed during operation will increase, which may cause problems, such as poor functioning or even breakdown of the magnetic head. An object of the invention is to provide a thin-film magnetic head having smaller dimensions, in which no impermissibly high heat-development during operation occurs. To this end, the thin-film magnetic head according to the invention comprises a thin film structure on a substrate, the structure comprising a flux conductor layer and first and second patterns of electrically conducting layers, each pattern having been produced during a same process, the pattern being located one above the other at ) separate levels and being at least partly located between the substrate and the flux conductor layer, the first layer pattern including a first winding having a first through-connection end, and a first connecting track as an integral extension of, and on the same level as the first winding, and the second pattern including a second winding having a second through-connection end, and a second connecting track as an integral extension of, and on the same level as the second winding, the through-connection ends being interconnected, wherein the first pattern further includes a first electrically conducting auxiliary track being located parallel and adjacent to the second connecting track of the second pattern, one end of the first auxiliary track being connected to the second connecting track and the other end being connected to a portion of the second connecting track connected to the second winding, and wherein the second pattern further includes a second auxiliary track being located parallel and adjacent to the first connecting track, one end of the second auxiliary track being connected to the first connecting track and the other end is connected to a portion of the first connecting track connected to the first winding. The connecting tracks and the auxiliary tracks together form current conductors of sufficiently large dimensions, so that the resistance is low and the heat development is limited. It is to be noted that JP-A 52-11920 discloses a film magnetic head structure on a substrate, which structure includes two electrical conductors each comprising a winding part extending between the substrate and a flux guide. The electrical conductors are located at separate levels and constitute three terminals of which a mid-point terminal is formed by connecting ends of both conductors. It is further to be noted that JP-A 1-92915 discloses a magnetic head which comprises a thin film structure including a one-layer coil and a conductor leading from the coil to an external terminal connection. The terminal connection is provided with layers of a metallic magnetic substance, which layers are formed simultaneously with magnetic core layers. To provide proper connections between the auxiliary tracks and connecting tracks, an embodiment of the thin-film magnetic head according to the invention is characterized, in that the first auxiliary track contacts the second connecting track along substantially the entire length of the second connecting track, and that the second auxiliary track connects the first connecting track along substantially the entire length of the first connecting track. A practical embodiment of the thin-film head according to the invention in particular formed as writing head, is characterized in that the connecting tracks have a width which is substantially the same as the width of the auxiliary tracks. The invention will now be described in greater detail with reference to an embodiment of the thin-film magnetic head according to the invention, shown in the accompanying Figures. Fig. 1 shows windings of a prior art thin-film writing head, Fig. 2 is a cross-sectional view of a prior art thin-film writing head provided with the windings of Fig. 1, Fig. 3 is a cross-sectional view of the prior art thin-film writing head in the region of the connecting tracks of the writing head, Fig. 4 shows windings of the thin-film writing head in accordance with the invention, Fig. 5 is a cross-sectional view of the thin-film writing head in accordance with the invention, provided with the windings shown in Fig. 4, and Fig. 6 is a cross-sectional view of the thin-film writing head in accordance with the invention, in the region of the writing head. Fig. 1 shows windings of a prior art thin-film writing head 1 provided on a substrate 2. The turns are assembled from two electrically conducting layers 3, 4, which, taken in a direction perpendicular to the substrate 2, are located one on top of the other, at two different levels 5, 6 (see Fig. 2). The first layer 3 is located on the substrate 2 and has a first connecting track 7 having a first connecting end 17 and a first winding 10, which has a first through-connection end 11 connected to a second through-connection end 12 of a second winding 13 of the second layer 4, located on the layer 3, and in addition contains a second connecting track 1, having a second connecting end 18. External means may be connected to the connecting ends. Fig. 2 is a cross-sectional view of a prior art thin-film writing head 1 provided with the windings shown in Fig. 1. The substrate 2 functions as a flux conductor and on a portion the electrically conducting layers a flux conductor layer 19 is located which, halfway the windings 10, 13, is connected to the substrate 2 and to a head face 20, with a spacing 21 from the substrate, the spacing 21 being filled by an insulating layer 22 and constituting a transducing gap 23. Insulating layers 22, 24 and 25 are present between the flux conductor layer 19, the substrate 2 and the layers 3, 4. Fig. 3 is a cross-sectional view parallel to the head face 20 in the region of the connecting tracks 7, 16. The connecting tracks extend parallel to each other at different levels 5, 6. If, for example, in the case of a multitrack recording system, the number of tracks must be doubled, for example for the purpose of obtaining higher information densities on a magnetic recording medium, the gap width b must be halved (see Fig. 1 and 4). If information is written by means of, for example, a multitrack writing head, also the dimensions of the connecting tracks 7, 16 and of the windings 10, 13 must be reduced to half the space between the tracks. When the layer thicknesses remain the same, this increases the resistance of the connecting tracks and the windings. Since only the dimensions in a direction parallel to the head face 20 must be halved and the dimensions in a direction perpendicular to the head face can remain the same, the resistance in the connecting tracks increases to a greater extent than the resistance in the windings. To reduce the heat developed during operation due to the increased resistance, enlarging the cross-sections of the connecting tracks has the best effect. It is also very difficult to enlarge the cross-sections of the windings, as this changes the ratios between the height and the other head dimensions, which may have detrimental effects. To that end, an improved thin-film magnetic head according to the invention, having a lower resistance, is provided with auxiliary tracks which are situated above and below the connecting tracks and contact the connecting tracks. Fig. 4 shows electrically conducting layers 103, 104, present on a substrate 102, of the thin-film writing head 101 of the invention. In addition to connecting tracks 107, 116 and windings 110, 113, these patterns are provided with a first and a second auxiliary track 131, 130. The auxiliary tracks have the same width b 2 as the width b 1 of the connecting tracks. Respective ends 132 and 133 of the second and first auxiliary track 130, 1313, respectively, are connected to the first and the second connecting track 107, 116, respectively. Furthermore, the further ends 134 and 135, respectively, of the respective second and first auxiliary track 130, 131 are connected to portion 108, 115 of the first and second connecting track 107, 116, respectively, which portion is in contact with the first and second windings 110, 113, respectively. Fig. 5 is a cross-sectional view of the writing head 101 in accordance with the invention, provided with the windings shown in Fig. 4 taken in the direction of the cross-section A-A. Also with this writing head the substrate 102 acts as a flux conductor and the substrate forms a magnetic yoke together with the flux conductor layer 119. The first auxiliary track 131, belonging to the first layer, is located under the second connecting track 11 of the second layer and connects the second connecting track along substantially the overall length of the second connecting track 116. The second auxiliary track 130 belonging to the second layer is located above the first connecting track 107 of the first layer and is in contact with the first connecting track along substantially the overall length of the first connecting track 107. Fig. 6 is a cross-sectional view parallel to the head face 120 in the region of the connecting tracks and auxiliary tracks of the writing head 101. The auxiliary tracks 130 and 131 are produced during the same process steps as those by means of which the windings and the connecting tracks are produced and are located at the same levels 105, 106 as the layers 103 and 104. It should be noted that the invention is not limited to the embodiment shown here. Also other head structures can be adapted in the same manner, for example read heads and combined write-read heads.

Claims: A thin-film magnetic head, comprising a thin film structure on a substrate (102), the structure comprising a flux conductor layer (119) and first and second patterns (103, 104) of electrically conducting layers, each pattern having been produced during a same process, the patterns being located one above the other at separate levels and being at least partly located between the substrate and the flux conductor layer, the first layer pattern (103) including a first winding (110) having a first through-connection end, and a first connecting track (107) as an integral extension of, and on the same level as the first winding, and the second pattern (104) including a second winding (113) having a second through-connection end, and a second connecting track (116) as an integral extension of, and on the same level as the second winding, the through-connection ends being interconnected, wherein the first pattern further includes a first electrically conducting auxiliary track (131) being located parallel and adjacent to the second connecting track (116) of the second pattern, one end (133) of the first auxiliary track being connected to the second connecting track and the other end (135) being connected to a portion (115) of the second connecting track connected to the second winding (113), and wherein the second pattern further includes a second auxiliary track (130) being located parallel and adjacent to the first connecting track (107), one end (132) of the second auxiliary track being connected to the first connecting track and the other end (134) is connected to a portion of the first connecting track connected to the first winding. A thin-film magnetic head as claimed in Claim 1, characterized in that the first auxiliary track (131) contacts the second connecting track (116) along substantially the entire length of the second connecting track, and that the second auxiliary track (130) connects the first connecting track (107) along substantially the entire length of the first connecting track. A thin-film magnetic head as claimed in Claim 1 or 2, characterized in that the connecting tracks (107, 116) have a width which is substantially the same as the width of the auxiliary tracks (130, 131).

Inventors: DRAAISMA EELTJE AIZE, PRONK FRANCISCUS A, VAN HEEREN ARIE HENDRIK, DRAAISMA, EELTJE AIZE, PRONK, FRANCISCUS A., VAN HEEREN, ARIE HENDRIK, DRAAISMA, EELTJE AIZE, INT OCTROOIBUREAU B.V., PRONK, FRANCISCUS A., INT OCTROOIBUREAU B.V., VAN HEEREN, ARIE HENDRIK, INT OCTROOIBUREAU B.V.
Applicants: PHILIPS ELECTRONICS NV, PHILIPS ELECTRONICS N.V.
Application year: 1991
Main classification: G11B5
IPC codes: G11B5