Patent Application
20070143984
The invention relates to a method of manufacturing a magneto-optical write/read head of the type defined in the preamble of independent claims 1 and 2 and to a write/read head of the type defined in the preamble of independent claims 8 and 9.
A method and a write/read head of the above type are known from Reference [1] which is herewith incorporated into the present specification by reference. Further details relating to magneto-optical heads of the kind referred to above may be found in references [2] and [3] which herewith are also both incorporated into the present specification by incorporation and which were not yet published at the priority date of the present application.
The magneto-optical write/read head described in reference [1] comprises a sliding head with integrated focussing lens and magnetic field modulating coil which has been designed and manufactured by the authors of the reference. The sliding head is intended for use with high data rate, first surface magneto-optical recording. A coil is integrated into the air bearing surface of the slider to maintain a head-disk distance of around 1 micron.
A dual layer coil is described made in a thin film process on a glass coil substrate by growing galvanic Cu between photoresist walls. Insulation between the two coil layers is achieved by a thin oxide layer. Because in this embodiment the completed coil faces the rotating disk, the coil is also covered with a few microns of oxide in order to protect it from damage by incidental mechanical contact with the disk.
A problem in the manufacture of write/read heads of this kind or write/read heads as defined in the preambles of independent claims 1 and 2, is the provision of means for contacting the thin film magnetic coil by electrically connecting the coil lead in and lead out sections to external lead in and lead out lines which are needed for connecting the coil to the external electronic circuitry needed for sending signals to and receiving signals from the coil. The coil is located on the outwardly directed surface of the coil substrate while the lead in and the lead out lines need to be connected at the opposite side of the coil substrate to terminals spaced from the coil substrate. The very small air gap present between a thin film in-plane magnetic coil of this kind and a rotating magneto-optical disc is too small (in the order of 1 micron) to accommodate the external lead in and lead out lines.
It is an object of the invention to provide a method of the kind described which overcomes the above indicated problems, is excellently suitable for the manufacture of digital magneto-optical signal write/read heads and does not require cumbersome manufacturing steps such as making deep via holes through the coil substrate and is characterized by the characterizing parts of independent claims 1 and 2 respectively.
Extending the coil lead in and lead out sections of the magnetic coil on the outwardly directed surface of the coil substrate to an interconnection part of the side surface of the coil substrate can easily be effected concurrently with the deposition of the coil itself on the coil substrate. For the deposition of the interconnecting conductors on the side surface of the coil substrate and contacting conductors on the top surface of the coil substrate deposition techniques may be used which are well known in the art of replication techniques and do not require the making of via holes through the substrate. In this way digital magneto-optical signal write/read heads may be produced at low cost which are suitable for use with magneto-optical discs and which demonstrate a very small head-disc distance while the magnetic coil may be brought into contact with the external lead in and lead out lines by suitable contacting means such as bonding, welding or soldering at the lead in and lead out sections respectively provided on the side surface of the coil substrate or with first and second contacting conductors respectively on the top surface of the coil substrate.
Preferred embodiments of the methods according to independent claims 1 and 2 respectively are defined in depending claim 3 and depending claim 4 respectively. These preferred embodiments involve the use of an auxiliary substrate to facilitate the handling of the delicate write/read heads of the invention and to facilitate the deposition of conducting material on the coil substrate in such a way that the interconnecting conductors on the side surface of the coil substrate are deposited such as to be in electrical contact with the coil lead in and lead out sections of the magnetic coil.
According to claim 5 the coil substrate may be detachably arranged on the supporting surface of the auxiliary substrate by adhesive means provided between the outwardly directed surface of the coil substrate and the supporting surface of the auxiliary substrate.
An advantageous embodiment of the latter method according to the invention in which an auxiliary substrate is used is defined in claim 6. This embodiment is important in view of the ease of handling a number of write/read heads simultaneously during the steps of providing a mask over a part of the coil substrate and depositing conducting material on the coil substrate.
A highly interesting embodiment of the invention for use in a method of manufacturing a digital magneto-optical signal write/read head according to the invention provided with first and second contacting conductors on the top surface of the coil substrate is defined in claim 7. In this way an optical lens part of an optical pick-up may be provided on the top surface of the coil substrate between the lead in and lead out conductors of the coil while any light focussed through the lens may pass through the coil substrate unobstructed by the lead in and lead out conductors. This embodiment provides extended freedom of design compared to the write/read head known from reference [1] in that the said optical lens part may be located eccentrically in relation to the central axis of the electromagnetic coil.
Independent claims 8 and 9 and claim 10 relate to digital magneto-optical write/read heads according to the invention, preferably manufactured by the method according to the invention.
The invention will now be described in more detail by way of non-limiting examples with reference to the drawings in which:
The figures in the drawing have been drawn to an arbitrary scale while certain dimensions have been exaggerated for the purposes of illustration. The same reference numbers have been used in the figures to designate the same or similar parts in the different figures.
The magneto-optical signal write/read head 1 further comprises a coil substrate 7, having substantially parallel main surfaces 5A, 5B interconnected by a joining side surface 9. In the embodiment shown in
A thin film magnetic coil 3 is deposited on the outwardly directed surface 5A of the coil substrate 7, comprising a continuous electrical conductor pattern with a coil lead in section 11, a coil winding section 13 and a coil lead out section 15 (see also
The whole digital magneto-optical signal write/read head 1 is suspended in a suitable unit that is very similar to a rotating or translating optical pick-up unit known from the prior art, provided with suitable suspension means for suspending the floating coil substrate 7 such as known per se for example from magnetic hard disc drive technology. Alternatively the coil substrate 7 could have a configuration different from that of a slider, for example for use with a stationary or slowly moving magneto-optical storage element instead of the magneto-optical storage disc 53. With such an embodiment no air film in the air gap 57 can be maintained and the coil substrate 7 could be actuated to move in the direction symbolized by the double pointed arrow 49 along the central axis 47 by a suitable actuator, for example an electromagnetic actuator of the kind well known from the prior art of electromagnetic actuators for optical and magneto-optical disc drives.
In the embodiment shown in
A description will now be given of the means for contacting the thin film magnetic coil 3 by electrically connecting the coil lead in and lead out sections 11, 15 to external lead in and lead out lines 25, 27 to and from the coil.
The coil lead in and lead out sections 11, 15 of the magnetic coil 3 on the outwardly directed surface 5A have been extended to an interconnection part 9A of the side surface 9 of the coil substrate 7. A pattern of respective first and second interconnecting conductors 21 and 23 has been provided by deposition on the interconnection part 9A of the side surface 9 of the coil substrate 7, in such a way that an electrical connection is provided to the lead in and lead out sections 11, 15 respectively of the magnetic coil 3. In the embodiment of the invention shown in
In the embodiment according to
The method of manufacturing the digital magneto-optical signal write/read head and more particularly the manufacture of the lead in and lead out conductors on the coil substrate thereof will now be described in more detail with reference more particularly to
An auxiliary substrate 33, which in
Subsequently, see
The provision of the mask 39 may be effected by means of a manufacturing step well known in the prior art for providing conducting areas or stripes on substrates and will therefore not be described in detail. The material used for providing the mask 39 may also be entirely conventional and could consist of for example a suitable photoresist.
As a further manufacturing step a layer of conducting material is deposited over at least a part of the mask 39 and over the said exposed areas. Suitable processes for depositing a layer of conductive material are known from the prior art, such as galvanic processes or sputtering processes. Subsequently the mask 39 and any conducting material deposited thereon is removed (see
As a last step the individual coil substrates 7 are removed from the auxiliary substrates 31, for example by melting or dissolving an adhesive layer provided between the detachably connected surfaces of the auxiliary substrate 33 and the individual coil substrates 7.
The individual coil substrates may have very small dimensions, for example length and width dimensions of the order of one or a few millimetres and a thickness of the order of 0.6 millimetres. Components having such small dimensions which need to be provided with thin film coils and deposited electrical conductors may be manufactured using manufacturing technology that is very similar to the prior art manufacturing technology used to manufacture for example thin film magnetic heads or chips. For example a wafer substrate of suitable shape could be provided, such as a glass substrate, on which a plurality of thin-film in-plane magnetic coils 3 may be deposited using suitable stepper replication techniques to produce a plurality of individual thin-film in-plane magnetic coils 3 each disposed on a corresponding coil substrate 7 provided in the wafer substrate.
An auxiliary substrate having dimensions in accordance with the wafer substrate could be disposed over the wafer substrate and over the thin-film in-plane magnetic coils. Subsequently, in a first dicing step, the wafer substrate may be diced in a first direction into individual wafer substrate strips comprising rows of coil substrates having thin-film in-plane magnetic coils deposited thereon while leaving the auxiliary substrate intact. In a second dicing step the auxiliary substrate and the said individual wafer substrate parts disposed thereover may be diced in a second direction different from the first direction into strip shaped auxiliary substrates 33 each supporting a plurality of diced individual wafer substrate parts comprising a coil substrate 7 and a thin-film in-plane magnetic coil 3 deposited thereon, the coil lead in and lead out sections 11,15 of each individual magnetic coil being formed such and the dicing steps being executed such that after the second dicing step a cross section of the lead in and lead out sections 11,15 is exposed at an edge of the interconnecting part 9A of a side surface 9 of the coil substrates 7.
In FIGS. 7 to 9 the strip shaped auxiliary substrates 33 show shallow grooves 65 which are present between the individual coil substrates 7 and which remain after the first dicing operation.
The manufacturing method which has been discussed with reference to
Although the invention has been described in relation to a limited number of embodiments of the invention, it should be appreciated that the invention is by no means limited to the embodiments described but instead is limited only by the scope of the independent claims 1, 2, 8 and 9. Interesting embodiments are described in the respective depending claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 01203755.2 | Oct 2001 | EP | regional |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10262381 | Oct 2002 | US |
| Child | 11565990 | Dec 2006 | US |
