METHOD FOR PRODUCING A PLATE ARRANGEMENT

Abstract

The invention relates to a method of producing a plate arrangement comprising two plates (1, 2) which, at least in sections, have an intermediate space (4) located between them and a constant distance (d) to one another and/or are arranged parallel to one another and between which a fusible solder material (3, 3′) is arranged. The task of setting a defined distance between the plates as accurately as possible is solved according to the invention by creating a pressure difference between the intermediate space (4) between the plates and the outer space surrounding the plates in such a way that the pressure in the outer space is higher than in the intermediate space (4) and that the temperature of the solder material (3, 3′) is at least temporarily raised above its melting temperature during the existence of the pressure difference.

Claims

1. A method for producing a plate arrangement, the method comprising: locating a first plate and a second plate parallel to each other or, at least in sections, a constant distance from each other, wherein an intermediate space is included, at least in sections, between the first plate and the second plate; joining the first plate and the second plate, wherein the joining includes: locating a fusible solder material in at least a portion of the intermediate space; producing a pressure difference between the intermediate space and an outer space surrounding the first plate and the second plate such that a pressure in the outer space is greater than a pressure in the intermediate space; and raising a temperature of the fusible solder material above at least one of a melting temperature or a bonding temperature of the fusible solder material during the pressure difference.

2. The method according to claim 1, wherein at least one of the first plate or the second plate is heated to above a softening temperature of a material from which it is formed while the pressure in the outer space is greater than the pressure in the intermediate space.

3. The method according to claim 2, wherein a first particle is located between the first plate and the second plate in the solder material, wherein a diameter of the particle corresponds to a desired distance between the first plate and the second plate, wherein the softening temperature is greater than the melting temperature of the fusible solder material, and wherein the softening temperature remains below a softening temperature of a material from which the first particle is formed.

4. The method according to claim 3, further comprising a second particle, and wherein the first particle and the second particle are located in the intermediate space along a channel.

5. The method according to claim 1, wherein, when the pressure in the outer space surrounding the first plate and the second plate is greater than the pressure in the intermediate space, the temperature remains below 350° C.

6. The method according to claim 5, wherein a particle is located in the fusible solder material, wherein a diameter of the particle corresponds to a distance to be achieved between the first plate and the second plate and wherein a softening temperature of the particle is higher than the at least one of the melting temperature or the bonding temperature of the fusible solder material, and wherein the temperature remains below the softening temperature of a material from which the particle is formed during the joining of the first plate and the second plate.

7. A method according to claim 1, wherein during the joining the first plate and the second plate the pressure difference between the intermediate space and the outer space of the plates is measured using a pressure measuring device.

8. A method according to claim 1, wherein, during the joining of the first plate and the second plate, the temperature is measured using a temperature sensor.

9. A system for producing a plate arrangement, the system comprising: a first plate; a second plate located parallel to or located, at least in sections, a constant distance from the first plate; a vacuum source for drawing off a fluid from an intermediate space between the first plate and the second plate.

10. The system according to claim 9, further comprising: a heater configured to control a temperature of the plate arrangement.

11. The method according to claim 1, wherein the pressure difference between the intermediate space and the outer space surrounding the first plate and the second plate is eliminated after lowering the temperature of the fusible solder material.

12. The method according to claim 1, wherein the pressure difference is between 10 mbar and 900 mbar, inclusive.

13. The method according to claim 1, wherein the pressure difference is applied for a duration of between one second and 120 seconds, inclusive.

14. The method according to claim 1, wherein the distance between the first plate and the second plate is at most 100 μm.

15. The system according to claim 9, further comprising: a device configured to cancel a pressure difference between the intermediate space between the first plate and the second plate and fill the intermediate with a functional medium.

16. The method according to claim 14, wherein the distance between the plates is between 5 μm and 100 μm, inclusive.

17. A method for producing a plate arrangement, the method comprising: locating a first plate and a second plate parallel to each other or, at least in sections, a constant distance from each other, wherein an intermediate space is included, at least in sections, between the first plate and the second plate; joining the first plate and the second plate, wherein the joining includes: locating a fusible solder material in at least a portion of the intermediate space; locating a particle in the fusible solder material; producing a pressure difference between the intermediate space and an outer space surrounding the first plate and the second plate such that a pressure in the outer space is greater than a pressure in the intermediate space; measuring the pressure difference between the intermediate space and the outer space; raising a temperature of the fusible solder material above at least one of a melting temperature or a bonding temperature of the fusible solder material during the pressure difference; measuring the temperature of the fusible solder material; lowering the temperature of the fusible solder material; and eliminating the pressure difference between the intermediate space and the outer space.

18. The method of claim 17, wherein a diameter of the particle corresponds to a desired distance between the first plate and the second plate, and wherein a softening temperature of the particle is greater than at least one of a melting temperature or a bonding temperature of the fusible solder material.

19. The method of claim 18, wherein the distance between the first plate and the second plate is between 5 μm and 50 μm, inclusive.

20. The method of claim 17, wherein the pressure difference is applied for up to thirty seconds.

Description

[0026] In the following, the invention is shown in Figures of a drawing on the basis of embodiments and is subsequently explained. In the drawings:

[0027] FIG. 1 shows a cross-section of two plates before joining,

[0028] FIG. 2 shows a cross-section of two plates after joining,

[0029] FIG. 3 shows a cross-section of two further plates before joining,

[0030] FIG. 4 shows the plates from FIG. 3 after joining,

[0031] FIG. 5 shows a cross-section of two further plates before joining with spacer particles,

[0032] FIG. 6 shows the two plates of FIG. 5 after joining with the spacer particles,

[0033] FIG. 7 shows two plates after joining with spacer particles that create flow channels,

[0034] FIG. 8 shows a cross-section of two plates before joining, together with a device for generating a vacuum, and

[0035] FIG. 9 is a diagram showing the temperature profile over time during the joining process as an example.

[0036] FIG. 1 shows a cross-section of a first plate 1 arranged parallel to and at a distance from a second plate 2. At least one or both of the plates may be made of an optically transparent medium, in particular glass, and may be manufactured by the float glass process or other suitable method in a flat, planar form. At least one of the plates, but in particular, as shown in FIG. 1, both plates, may be covered with a functional layer or with a functional material 6, 7 on the surface facing the other plate, at least partially or in sections. The functional layers can be in the form of a solid layer, a gel layer or a liquid layer.

[0037] The object of the method according to the invention is to bring the two plates 1, 2 to a defined distance from each other and, if possible, to the same distance at all points over long sections. Ideally, the distance d between the plates 1, 2 is of the order of a few micrometers to a few tens of micrometers and varies as little as possible over the area over which the two plates 1, 2 are parallel to each other, ideally by less than 5 μm.

[0038] At least one of the plates 1, 2 or both plates are covered with a solder material 3, 3′ on the surface facing the other plate. In this case, the partial surfaces of the two plates 1, 2 covered with the solder material may be directly opposite each other or may be displaced relative to each other.

[0039] In FIG. 1, the lower, second plate 2 is shown to have two suction openings 8, 9 in the form of bores through which a fluid, in particular gas, can be drawn off. The arrows indicate that a gas pressure, such as atmospheric air pressure, acts on the upper, first plate. When the two plates 1, 2 are placed on top of each other, gas, in particular air, can begin to be extracted through the suction openings 8, 9. If the plates 1, 2 are at least partially sealed at their periphery, for example by the coatings of a solder material 3, 3′ resting on each other, and at the latest when the solder material melts, the pressure in the intermediate space 4 between the plates 1, 2 can be lowered. Partly due to the weight force acting on the first plate 1 and assisted by atmospheric pressure or otherwise generated overpressure, the plates 1, 2 may be further compressed, improving the seal at their periphery and further lowering the pressure in the intermediate space 4. The pressure difference between the intermediate space 4 and atmospheric pressure can be between 10 and 900 mbar. The purpose of the generated pressure difference is, among other things, the application of a homogeneous force over the entire surface in order to achieve a gap thickness that is as homogeneous as possible.

[0040] Usually, the temperature of the plates 1, 2 and the solder material 3, 3′ is already raised before the application of a suction device. The temperature is increased on the one hand by the melting temperature of the solder material 3, 3′ and on the other hand also by the softening temperature of the material of the plates 1, 2, for example the softening temperature of the glass used. When the temperature rises above the melting temperature of the solder material 3, 3′ during heating, the flowability of the solder material causes the intermediate space 4 between the plates 1, 2 to be sealed, the pressure in the intermediate space 4 may decrease, and the force acting on the plate 1 due to the acting pressure difference may further increase.

[0041] The temperature is raised above the softening temperature of the material, for example the glass, of which the plates 1, 2 are made. As a result, the plates 1, 2 become plastically deformable and the plate 1 lowers onto the plate 2 to such an extent that the distance between the plates 1, 2 or between the functional media 6, 7 or between one plate and a functional medium arranged on the opposite plate is reduced to a few micrometers. The functional media 6, 7 can touch each other in some places to adjust the distance of a few micrometers.

[0042] If the temperature is lowered again after joining, the plates 1, 2 solidify, and the distance is maintained even after the pressure difference between the intermediate space 4 and the outer space has been eliminated, in particular after a pressure of about 1000 mbar has been applied in the intermediate space 4. This condition is shown in FIG. 2. For example, the pressure difference can be applied for a duration between 1 and 120 seconds. The distance between the plates 1, 2 is denoted by d and may be, for example, at most 100 μm.

[0043] FIG. 3 shows the same initial situation as in FIG. 1. The plates 1, 2 are pressed against each other by the own weight of plate 1 as well as a pressure difference when gas is sucked through the openings 8, 9. In contrast to the method described with reference to FIGS. 1 and 2, a solder material and a material for the plates 1, 2 are used here which are such that the melting temperature of the solder material 3, 3′ is below the softening temperature of the material/glass from which the plates 1, 2 are made. If one of the plates 1, 2 consists, for example, of a toughened safety glass whose mechanical properties do not permit heating above 350° C., this temperature value must not be exceeded and the melting point of the solder material must be below this temperature.

[0044] Starting from the state shown in FIG. 3, the plates 1, 2 are placed one on top of the other, and by creating negative pressure in the intermediate space 4, the plates 1, 2 are pressed against each other. At the same time, the solder material 3, 3′ is liquefied and bonds with both plates 1, 2, as shown in FIG. 4. If the solder material 3, 3′ is viscous, the temperature control can be operated such that the time over which the solder material is liquefied is sufficient to distribute the solder material between the plates 1, 2 sufficiently to set the desired distance d between the plates 1, 2 or the desired distance between the functional media 6, 7. The temperature is then lowered so that the solder material solidifies and holds the plates 1, 2, which elastically move away from each other again when the pressure difference ceases. The distance between the plates 1, 2 then remains essentially constant, as they are held by the solder material even after the pressure difference has ceased.

[0045] FIG. 5 shows an initial state with two plates 1, 2 between which particles 5, 5′, for example in the form of glass spheres, are arranged. As an example, the particle 5 is shown as a free particle between the plates 1, 2, while the particle 5′ is integrated into the solder material 3′.

[0046] As explained above, a pressure difference is created between plates 1, 2 with a simultaneous increase in temperature. In one case, the solder material and the material of the plates 1, 2 can be matched to each other in such a way that the softening temperature of the material of the plates 1, 2 is not reached for melting the solder material, or the materials can also be selected in such a way that the melting temperature of the solder material 3, 3′ is approximately at the softening temperature of the material of the plates or above this softening temperature. Therefore, in principle, both the operations illustrated in FIGS. 1 and 2 and the operations illustrated in FIGS. 3 and 4 may be carried out in the manufacture of the plate arrangement.

[0047] In any case, the distance d between the plates 1, 2 will not be less than the diameter or the external dimensions of the particles 5, 5′. The diameter of the particles 5, 5′ is, for example, 5 to 50 μm. The particles 5, 5′ thus act as spacers and set the minimum distance d. This occurs both when plates 1, 2 are softened and in the variant of the method in which plates 1, 2 are not softened. Thus, by means of the spacing particles 5, 5′, the desired spacing of, for example, 5 to 50 μm between the plates 1, 2 or between the functional media 6, 7 can be set.

[0048] FIG. 7 shows that if the plates are heated sufficiently above their softening temperature, they may nevertheless deform to such an extent that they approach each other to a distance less than the outer dimensions of the particles in the areas where no spacing particles are located. In this case, the particles 5, 5″ may be selectively arranged so that they are positioned in rows or along straight or curved lines. In the immediate vicinity of particles, the plates 1, 2 will not be able to approach each other as far as in the areas distanced from the particles 5, 5″. This leads to the formation of cavities in the immediate vicinity of the particles. When the particles are arranged in a row or line, said cavities connect to form channels which are available for fluid transport in the intermediate space 4 between the plates 1, 2 and may serve to better transport media to be transported into or removed from the intermediate space. This is particularly easy to do, for example, if the particles 5″ can be arranged within a solder material and held in place by it before the solder material softens. However, the particles may also be fixed to one of the plates by adhesive or other means prior to the plate arrangement manufacturing process.

[0049] FIG. 8 shows in cross-section an arrangement with two plates 1, 2 before they are joined together, wherein a vacuum device is arranged below the second plate 2 for extracting a fluid from the intermediate space 4. The vacuum device has a base plate 13 and a suction pump (not shown). A central suction channel 10 is shown within the base plate 13. Connected to these are suction channels 8′, 9′, each of which opens at bores 8, 9 of the second plates, through which a fluid can be sucked out of the intermediate space 4.

[0050] The additional channels 11, 12 terminate at the lower plate 2 where they create a negative pressure that holds the plate 2 to the base plate 13. Thus, the plate arrangement can be easily handled while performing the process by means of the base plate 13.

[0051] After sealing the space between the plates 1, 2 and creating a negative pressure in the space 4, the channel 10 can be closed so that the remaining negative pressure both maintains a negative pressure in the intermediate space 4 and creates a pressing force of the plate arrangement 1, 2 against the base plate 13. The temperature treatment can then take place in this state. Following the temperature treatment, the channel 10 may be opened to remove the negative pressure in the intermediate space 4 and to obtain a normal atmospheric pressure of about 1000 mbar in the intermediate space 4. The distance between the plates remains the same. This enables or facilitates a subsequent filling of the intermediate space 4 with functional media, such as a gas or a liquid. This can be achieved by means of a device for cancelling the pressure difference between the intermediate space 4 of the plates 1, 2 and for filling the intermediate space 4 of the plates 1, 2 with a functional medium (not shown).

[0052] FIG. 9 shows in a diagram the course of the temperature to which the plate arrangement 1, 2 is subjected over a time t. The temperature T is initially raised from the room temperature T.sub.0 over an initial period up to time t.sub.1. At about this time, the application of negative pressure begins by drawing fluid through the openings 8, 9 in the plate 2. The temperature can then be increased slightly above the temperature T.sub.1. The elevated temperature is maintained for a certain time until about time t.sub.2 and then lowered. The suction process can be stopped before time t.sub.2 or only at time t.sub.2. The temperature is then slowly lowered until time t.sub.3. After time t.sub.3 the temperature can be lowered further to room temperature.

[0053] The temperature T.sub.1 is the melting temperature of the solder material 3, 3′. As the temperature is raised above this melting temperature, whether or not the plates are softened depends on whether or not their softening temperature is above or below the melting temperature of the solder material and is reached at least some of the time during the method described.

[0054] By selecting the materials used, with coordinated softening or processing temperatures, it can be achieved, with suitable temperature control, even over time, i.e. when setting a time-dependent temperature profile, that a fluid-tight connection of the plates 1, 2 to one another is created by melting the solder material, whereby, in addition, the desired distance between the plates or between the functional media located between them can be set precisely and with the smallest location-dependent deviations.