HK1063165B - Method and device for assembling substrates - Google Patents

Description

Method and apparatus for bonding substrates

Technical Field

The invention relates to a method and a device for joining at least two substrates, in particular for forming an optical data carrier, in which method or device the substrates are placed at a distance from one another between two oppositely arranged and mutually movable plates.

Background

Such a device is known, for example, from DE 19927516.5, which is not published beforehand by the applicant. In the known device, at least one first substrate is provided with a double-sided adhesive film. The substrate is then placed with the adhesive film up on the first plate. A centering pin is provided on the first plate, which is guided into the inner bore of the substrate and is centered. The second substrate is then positioned over the first substrate and held parallel and spaced over the first substrate by suitable ear pieces on the centering pins. A closed chamber is then formed around the substrate, in which chamber a negative pressure is applied. When the desired pressure is reached, a pressure plunger located in the chamber is moved downwardly to press the two substrates together and to bond them to each other. After pressing together, the adhesive film between the substrates is cured in a suitable manner.

One problem with this arrangement is that the support plate and pressure plunger must be held precisely planar parallel to uniformly join the two substrates, which adds significantly to the complexity and cost of the arrangement.

Disclosure of Invention

Based on the prior art, the invention aims to provide the following steps: a method and apparatus for bonding substrates are provided, in which the substrates can be uniformly bonded in a simple and low-cost manner.

According to the invention, this object is achieved in a method for joining at least two substrates, in particular for forming an optical data carrier, in which the substrates are arranged at a distance from one another between two oppositely arranged and mutually movable plates, by: at least one plate is connected to the elastic membrane and is moved by creating a pressure difference on two opposite sides of the membrane. By arranging one plate on an elastic membrane, a floating support of the plates is obtained, which allows a good and even fit of the two plates to each other when the substrates are joined. Thereby it will be ensured that the substrates are pressed together uniformly. Furthermore, a high contact pressure can be achieved by a small pressure difference between the two opposite sides of the membrane.

In a preferred embodiment of the invention, an underpressure is applied in a first chamber surrounding the plate, a wall of which first chamber is at least partially formed by the membrane. By generating a negative pressure in the first chamber surrounding the plate, it is possible to generate the required pressure difference on the one hand and the substrate engagement under negative pressure on the other hand, which makes it possible to considerably reduce the risk of air being contained between the substrates.

Preferably, a negative pressure is applied in the second chamber on the side of the membrane facing away from the plate, in order to keep the membrane and the plate arranged thereon first separated from the other plate. In this case, it is preferred to maintain the pressure in the second chamber lower than the pressure in the first chamber before the substrates are bonded, thereby avoiding uncontrolled and premature relative movement of the plates. In a preferred embodiment of the invention, for joining the substrates, the pressure in the second chamber is brought to the pressure of the surroundings, while the pressure in the first chamber is maintained at a negative pressure. The pressure in the second chamber is controllably brought to ambient pressure, whereby the relative movement of the two plates can be controlled. This reliably provides uniform bonding of the substrates.

Pressure is preferably applied to the first chamber after the substrates are bonded to separate the plates from each other. Furthermore, the pressure in the first chamber will cause a hardening of the adhesive located between the substrates.

According to a particularly advantageous embodiment of the invention, the substrates are kept spaced apart from one another by a centering pin inserted into the inner bore of the substrates before the substrates are joined, as a result of which, on the one hand, the substrates are centered with respect to one another and, on the other hand, undesired and uncontrolled joining of the substrates is avoided.

The object of the invention is also achieved in a device for joining at least two substrates, in particular for forming an optical data carrier, having two plates arranged opposite one another and movable relative to one another for joining the substrates, by: wherein at least one plate is connected to the elastic membrane and is provided with a means for generating a pressure difference on two opposite sides of the membrane. The advantage already mentioned above is achieved by connecting one plate to an elastic membrane, that is to say the plate is supported in a floating manner and thus a good fit to the other plate can be achieved. In addition, a high contact pressure can be achieved by a small pressure difference on the two opposite sides of the membrane, since this pressure difference acts on the larger surface of the plate and the membrane.

Preferably, a substantially closed first chamber is formed on the first side of the membrane, so that a pressure difference can be generated on both opposite sides of the membrane. In a preferred embodiment of the invention, it is advantageous to provide a substantially closed second chamber on the second side of the membrane to ensure good controllability of the pressure difference.

Preferably, at least one source of underpressure is provided, which is connectable to the first and/or second chamber. The negative pressure source can generate the required pressure difference and can realize the bonding of the substrates in the negative pressure environment, thereby avoiding the air inclusion between the substrates.

In a preferred embodiment of the invention, at least one pressure source is also provided, which is connectable to the first and/or second chamber in order to generate the required pressure difference or to maintain the substrates in a pressure environment after joining and to cure the adhesive located between the substrates.

Preferably all the plates are arranged together in one chamber. In order to limit the movement of the membrane and the plate in the direction away from the other plate, it is preferred that an opposing abutment is provided on the side of the membrane facing away from the plate. The life of the membrane can be significantly extended by this motion limitation, since in practice it is only deflected in one direction.

For a proper and uniform loading of the membrane and a good adaptation of the plates to each other, it is preferred that the plates are arranged substantially horizontally. In this case, the plate mounted on the membrane is preferably arranged above the other plate. This arrangement can achieve: a plate provided on the membrane cooperates with a plurality of plates provided on, for example, a circular table. This can reduce the cost and increase the yield of the apparatus. Furthermore, successive uniform processing results can be produced by using the same film. In a preferred embodiment of the invention, the membrane is prestressed upward against a counter-bearing by means of an elastic element, preferably a spring.

Preferably, a centering pin is provided on one of the plates, which centering pin can be guided into the inner bore of the substrate in order to be centered on one another when the substrates are joined. To ensure controlled engagement of the substrates, the substrates are preferably maintained spaced apart and substantially parallel to each other by centering pins prior to substrate engagement.

The method and the device according to the invention are particularly suitable for optical recording media, such as CDs, DVDs, etc., in which two substrates are adhesively bonded to one another to form a data carrier. It is of course also possible to join a plurality of substrates in the manner described above. The method and the device according to the invention can advantageously be used in combination with a device in which a double-sided adhesive film is applied to the substrates before the substrates are joined, as is known from DE 19927516.5, which is not previously published by the applicant, which is made in connection with the subject matter of the invention and is not repeated here.

Drawings

The invention will be described in detail below with the aid of preferred embodiments and with reference to the attached drawings. The attached drawings are as follows:

FIG. 1: a schematic cross-sectional view of the substrate bonding apparatus in a first position prior to substrate bonding;

FIG. 2: a schematic cross-sectional view of the substrate bonding apparatus in a second position during substrate bonding;

FIG. 3: a schematic view of a centering pin for use in the device according to fig. 1;

FIG. 4: a cross-sectional schematic view of a modified embodiment of a substrate engaging apparatus.

Detailed Description

Fig. 1 shows a device 1 for joining two substrates 3, 4, each having an inner opening, which substrates form, for example, a CD or VCD or other data carrier. Figure 1 shows the device in a position before the substrates 3, 4 are joined. In order to ensure that the substrates 3, 4 are bonded together when they are joined, an adhesive 5 in the form of a double-sided adhesive film is applied to the substrate 4, as can be seen in fig. 1. The double-sided adhesive film and the corresponding device for applying the adhesive film are known, for example, from DE 19927516.5, which was not previously published, from the applicant, and in this respect it was made to the subject matter of the present invention and is not repeated here.

The device 1 has a housing 7, which housing 7 is formed by two half-shells 9, 10 which are movable relative to one another, each half-shell having a substantially U-shaped cross-section. In the moved-together state, the two half-shells 9, 10 form a chamber 12 between them. The chamber 12 forms a seal to the periphery at the interface 14 between the two half-shells 9, 10.

In the half-shell 10 shown in fig. 1, which represents the lower half-shell, a plastic elastic membrane 16 is provided which is arranged in a completely tensioned manner in the interior region of the half-shell 10 and thus divides the chamber 12 formed between the two half-shells 9, 10 into an upper chamber half 18 and a lower chamber half 19. Of course, the membrane 16 may be formed of other suitable materials, such as metal.

The lower chamber half 19 applies a negative pressure to the half-shell 10 via a negative pressure source 22, such as a vacuum pump, and a corresponding conduit 23, as will be described in more detail below. In a similar manner, the upper half-chamber 18 applies a negative pressure in the upper half-shell 9 through a negative pressure source 26 and a corresponding conduit 27. The upper chamber half 18 also exerts a pressure in the upper housing half 9 via a pressure source, such as a pump 30, and a corresponding line 31. The function of these negative and pressure sources is described in more detail below.

A plate 34 is provided on the membrane 16 towards the upper chamber half 18 in a suitable manner so that the plate 34 is movable together with the elastic membrane 16. For example, the plate 34 may be adhered to the membrane 16, or the plate 34 and a not shown clamping ring may clamp the membrane 16 therebetween.

A centering pin 36 is provided on the plate 34, for which purpose it will be described in greater detail below with reference to fig. 3.

An upper plate 38 is provided in the upper half-shell 9, which is placed opposite the plate 34. The upper plate 38 has a central aperture 40 into which the centering pin 36 can move when the lower plate 34 moves toward the upper plate 38, as shown in FIG. 2.

Plates 34 and 38 have a geometry that matches the substrate. Plate 38 is shown in figure 1 as a separate component provided on half shell 9. Of course, it can also be formed integrally with the half-shell 9, or the inner wall of the half-shell 9 can serve as a plate or as an opposite face to the lower plate 34, whereby an additional plate, such as the plate 38, can be dispensed with.

In the lower half-chamber 19 there are two counter-supports 42, which are actually arranged below the plate 34. The counter bearing limits the movement of the membrane 16 and the upper plate 34 in the downward direction, whereby the membrane 16 can be deflected essentially only upwards, which prolongs its service life. Of course, instead of two counter rests, only one counter rest 42, preferably arranged in the middle, can also be provided. It is also possible to arrange the counter-rests in such a way that they overlap the area of the membrane 16 not covered by the plate 34 in order to receive the force acting on the membrane 16 in this area.

The structure of the centering pin 36 will be described in detail with reference to fig. 3. The structure of the centering pin has been described in great detail in DE 19927516.5, which is a non-prepublished publication from the applicant, in this respect it was made to the subject matter of the present invention and is not repeated here. The centering pin 36 has an upwardly open cavity 45 bounded laterally by surrounding sidewalls and downwardly by the bottom 48 of the pin 36. The outer circumference of the wall 47 is adapted to the shape of the inner bore of the substrates 3, 4, in particular in the lower region where the pins have a precisely ground outer circumference, in order to ensure good centering and guidance of the two substrates 3, 4. The wall 47 is inclined at its upper end thereby defining an upwardly tapering ramp 49. Ramp 49 may be provided to center and guide the substrate as it is received on pin 36.

A plurality of movable ears 50, only two of which are shown in fig. 3, are provided on the side walls 47 of the pins 36. In the presently preferred embodiment, four ears 50 are provided. The ear piece 50 is pivotally mounted on the wall 47 of the pin 36 in a suitable manner so that the ear piece can be moved between the positions shown in fig. 1 and 2.

The lug 50 is biased radially outward from the pin 36 by a compression spring 52 into the position shown in fig. 3 and can be pivoted against this spring preload into the position shown in fig. 2. A cone 53 is provided in the cavity 45 of the pin 36, which cone tapers upwards and is movable in the cavity 45. The cone 53 is pre-pressed upwards in the position shown in fig. 3 by a spring 55.

The compression spring 52 is supported with one end on the cone 53 and with its other end on the ear piece 50, pressing it outwards. The spring 52 can slide along the conical surface of the cone 63, in which case the cone will press downwards against the pre-pressure of the spring 55, thereby changing the outward pre-pressure.

The earpiece 50 has a straight outer surface on which the substrate can slide down and be accurately guided. The second substrate 3 can be placed on the ear piece 50 when the first substrate 4 with the adhesive layer 5 located thereon is moved to the position shown in fig. 3. The base sheet 3 is held in the position shown spaced relative to the first base sheet 4 by the ears 50 being preloaded radially outwardly. In this case, the substrate 3 can be held parallel to the substrate 4 by the straight outer surfaces of the ear pieces 50. When the substrate 3 is pressed in the direction of the substrate 4 or the substrate 4 is pressed against the substrate 3, the ear 50 will be pressed inwards against the pre-stress of the spring 52, whereby the substrate 3 can be moved in the direction of the substrate 4. During this movement, the substrate 3 is guided precisely centered relative to the substrate 4 and remains parallel thereto.

The substrates are held apart from one another by ears on the centering pins as shown prior to engagement of the substrates. The spaced holding can also be achieved by means of radially outwardly preloaded balls, spring rings, pins or the like, which allow the substrates to be spaced apart and held substantially parallel to one another before joining.

The operation of the device 1 according to the invention will be explained in detail below with the aid of fig. 1 and 2. For loading of the device 1, the half-shells 9 and 10 are moved away from each other in order to place the substrates 4 and 3 on the plate 34 or on the centering pins 36 by means of the handling device. In this case, the substrate 4 is placed on the plate 34 together with the adhesive layer 5 provided thereon and directed upward. The substrates 3 are then placed on the lugs 50 of the centering pins 36 in such a way that the substrates 3, 4 are spaced apart and parallel to one another.

The half shells 9, 10 will now be moved to the position shown in fig. 1, whereby the upper chamber 18 is sealed off from the surroundings. In this case, the upper plate 38 is in contact with the side of the substrate 3 facing upwards, but the substrates 3, 4 are still kept spaced apart from one another by the centering pins 36. A negative pressure will then be created in the lower chamber 19 by means of the vacuum pump 22 and the conduit 23. Simultaneously or indirectly, a negative pressure is also generated in the upper chamber 18 by means of the vacuum pump 26 and the conduit 27. In this case it will be ensured that: the pressure in the lower chamber 19 is lower than the pressure in the upper chamber 18 so that the membrane is reliably pulled towards the counter-abutment 42. Once a desired pressure is reached in upper chamber 18 that prevents air from being trapped between the substrates, the pressure in lower chamber 19 is controllably raised to ambient pressure. The pressure difference thus created between the two chambers 18, 19 and the negative pressure in the upper chamber 18 will cause the membrane 16 and the plate 34 provided thereon to be controllably moved upwards towards the upper plate to the position shown in fig. 2. In which position the substrates 3, 4 are pressed together uniformly. A good fit of the plate 34 to the upper plate 38 is obtained by the plate 34 being floatingly supported, whereby a uniform pressing force will be exerted on the substrate.

The negative pressure in the upper chamber is then also raised to ambient pressure, thereby causing the membrane 16 and plate 36 to move downward again. The two joined substrates move with plate 34 and away from plate 38. The membrane 16 is supported on the counter bearing 42, which prevents the membrane from flexing downwards.

The pressure in the upper chamber 18 is now brought to an overpressure by means of the pump 30 and the conduit 31 in order to accelerate the bonding or curing process of the adhesive 5 between the substrates 3, 4. Alternatively, the adhesive can also be cured in the device 1 by other methods, such as Ultraviolet (UV) radiation or the like. Of course, the adhesive can also be cured in a separate curing station.

To unload the substrates 3, 4 thus engaged, the upper and lower half-chambers 9, 10 are moved away from each other in order to open a suitable handling device for the removal of the substrates.

Fig. 4 shows an alternative embodiment of the invention. Fig. 4 shows a device 100 for joining two substrates 103, 104 having inner bores, as in the first exemplary embodiment, for example, to form a CD or DVD or other data carrier. In order to ensure the adhesion of the substrates 103, 104 when they are joined, an adhesive 105 in the form of a double-sided adhesive film is applied to the substrate 104.

The device 100 has a housing 107 which is formed from two relatively movable half-shells 109, 110, each having a substantially U-shaped cross-section, as in the first embodiment. In the moved-together state, the two half-shells 109, 110 form a chamber 112 in the middle thereof, which forms a seal with the periphery at the interface 114 between the two half-shells 109, 110.

In the upper half-shell 109, an elastic membrane 116 is provided, which is arranged in a completely tensioned manner in the interior region of the half-shell 109 and thus divides the chamber 112 formed between the two half-shells 109, 110 into an upper half-chamber 118 and a lower half-chamber 119.

The upper chamber half 118 applies negative pressure to the upper shell half 109 through a negative pressure source 122, such as a vacuum pump, and a corresponding conduit 123. In a similar manner, the lower chamber half 119 can apply a negative pressure to the lower half 109 via a negative pressure source 126 and a corresponding conduit 127. The upper chamber 118 can also exert pressure in the upper housing half 109 via a pressure source, such as a pump 130, and a corresponding conduit 131.

A plate 134 is provided on the membrane 116 towards the lower chamber half 119 in a suitable manner so that the plate 134 is movable together with the elastic membrane 116.

In the lower housing half 110, a lower plate 138 is provided, which is placed opposite the plate 134 and on which the centering pin 136 is mounted. The centering pin 136 has the same structure as the centering pin 36 according to the first embodiment. The upper plate 134 provided on the membrane 116 has a central aperture 140 into which the centering pin 136 can move when the upper plate 134 is moved towards the lower plate 138.

An opposing support 142 is provided in the upper chamber 118 to limit upward movement of the membrane 116 and the plate 134 provided thereon, i.e., into the chamber 118.

The membrane 116 is prestressed against the counter-bearing 142 by means of a spring 144 which extends between the upper half-shell 109 and the membrane 116. The force of the spring 144 is designed such that when the pressures in the chambers 118 and 119 are equal, the membrane tends to be drawn towards the counter-abutment 142 so as to keep the membrane 116 and the plate 134 provided thereon in the position shown in figure 4. Other pre-pressing means may of course be provided so that the two plates are pre-biased apart from each other.

The operation of the device 100 according to fig. 4 is essentially the same as in the case of the first embodiment, but wherein in the case of the embodiment according to fig. 4 a negative pressure is first generated in the upper chamber 118 and subsequently in the lower chamber 119 in order to avoid an uncontrolled joining of the substrates 103, 104.

The main difference between the embodiments shown in fig. 1 and 4 is that: the plate provided on the membrane in the embodiment according to fig. 4 is arranged above the plate rigidly mounted on the housing. Furthermore, vacuum pumps 122, 126 and pressure pump 130 are connected to respective conduits 123, 127, 131, all of which are provided in the upper shell half 109. There is no conduit in the lower housing half 110 to form a connection with a pump or vacuum pump.

The lower housing 110 can thus form a circular table in a simple and cost-effective manner, which is provided with a plurality of such lower housing halves 110. The upper half-shell 109 can thus be used for a plurality of lower half-shells 110, which increases the throughput of the device, since the loading and unloading of substrates can take place outside the region of the upper half-shell 109.

Although not shown in the figures, the plates 134, 138 may have suitable surface structures, e.g. grooves, directed towards the substrates 103, 104, by means of which surface structures, e.g. air pressure, can be applied to the substrates to press them together. Such a structure for pressing the substrates together by directly applying compressed air is also described in the above-mentioned DE 19927516.5, which is made in this respect to the subject matter of the present invention and is not repeated here.

The invention has been described with reference to the preferred embodiments thereof, but is not intended to be limited to the specifically described embodiments. For example the shape of the housing may be different from the shape of the housing described. In the embodiment according to fig. 4, in particular, the lower half-shell 110 can also be made flat, while the U-shaped edge of the upper half-shell is lengthened. The plate may then form a seal with the upper housing half 109 to form upper and lower chambers. Features of one embodiment may also be used in other embodiments, only those features being suitable. It is also possible to provide only one chamber to create a pressure difference on each side of the membrane. It is sufficient that only one plate and chamber receiving the substrate is subjected to a negative pressure. In order to avoid uncontrolled substrate engagement before the predetermined pressure is reached in the chamber, the membrane may be held in its position, in which the plates are spaced apart, for example by a spring, electromagnet or other holding means.

Claims (24)

1. Method for joining at least two substrates to form an optical data carrier, comprising the steps of: the substrates are placed at a distance from each other between two oppositely arranged and relatively movable plates, wherein one plate is connected to an elastic membrane and is freely movable together with the elastic membrane, and the two substrates are joined together by moving at least the plate connected to the elastic membrane towards the other plate by creating a pressure difference on both opposite sides of the membrane.

2. A method according to claim 1, characterized in that: a negative pressure is applied in a first chamber surrounding a plate, a wall of which is at least partially formed by a membrane.

3. A method according to claim 2, characterized in that: a negative pressure is applied in a second chamber, which is located on the side of the membrane facing away from the plate.

4. A method according to claim 3, characterized in that: the pressure in the second chamber is maintained lower than the pressure in the first chamber before the substrate is bonded.

5. The method according to claim 4, characterized in that: the pressure in the second chamber is brought to ambient pressure for bonding the substrate, while the pressure in the first chamber is maintained at a negative pressure.

6. Method according to one of claims 2 to 5, characterized in that: pressure is applied to the first chamber after the substrates are bonded.

7. Method according to one of claims 1 to 5, characterized in that: the substrates are held in spaced relation to one another by a centering pin inserted into an internal bore of the substrates prior to substrate engagement.

8. Device for joining at least two substrates to form an optical data carrier, comprising two plates arranged opposite and movable relative to each other for pressing said substrates, at least one elastic membrane for fixing said one plate, which plate is connected to and moves together with said elastic membrane only; also included is a means for creating a pressure differential across the two opposing sides of the elastic membrane and moving the plate attached to the elastic membrane.

9. The apparatus of claim 8, wherein: a closed first chamber is formed on the first side of the membrane.

10. The apparatus of claim 9, wherein: a closed second chamber is provided on the second side of the membrane.

11. The apparatus according to claim 9 or 10, characterized in that: a source of negative pressure is provided which is connectable to the first and/or second chamber.

12. The apparatus according to claim 9 or 10, characterized in that: at least one pressure source is provided, which is connectable to the first and/or second chamber.

13. The apparatus according to claim 9 or 10, characterized in that: all the plates are arranged together in one chamber.

14. The apparatus of claim 13, wherein: an opposing abutment is provided on the side of the membrane facing away from the plate for limiting the movement of the membrane and the plate in one direction.

15. Device according to one of claims 8 to 10, characterized in that: the plates are arranged horizontally.

16. Device according to one of claims 8 to 10, characterized in that: the plate mounted on the membrane is arranged above the other plate.

17. Device according to one of claims 8 to 10, characterized in that: a centering pin is provided on one of the plates and is insertable into the inner bore of the substrate.

18. The apparatus of claim 17, wherein: the substrates are maintained spaced apart and parallel to each other prior to substrate bonding.

19. Device according to one of claims 8 to 10, characterized in that: the plates are pre-biased apart from each other by a pre-biasing means.

20. The apparatus of claim 19, wherein: the pre-biasing means has at least one spring.

21. The apparatus of claim 8, wherein: the plate attached to the flexible membrane has a flat pressure surface.

22. The apparatus of claim 8, wherein: the plate attached to the elastic membrane is a rigid plate.

23. The apparatus of claim 9, wherein: the elastic membrane extends completely across the chamber and constitutes a wall of the chamber.

24. The apparatus of claim 8, wherein: the at least one plate is connected to the elastic membrane on the side facing away from the substrate.