DE4223568C1 - Aluminium@-zinc@ coating of foil esp. for capacitor - by vapour deposition while introducing oxygen@ - Google Patents

Abstract

(A) In the prodn. of an Al-Zn layer coated foil web (40), esp. for capacitors, by vapour deposition in a pressure-tight housing having a web uncoiling, advancing and coiling system (29) and two vapour sources (19,20), the novelty is that oxygen is dosed vapour deposition of Al and Zr onto the foil web. (B) Also claimed are (i) appts. for carrying out the process; and (ii) a foil web which is produced by the process and which has a vapour deposited mixed layer consisting of a Zn layer and an Al-Al2O3 layer, the Al content being 0.5-20 wt.%. USE/ADVANTAGE - The process is used to coat paper or plastic foils for capacitors. The coated foil is less susceptible to corrosion and retains its original properties after a long storage time.

Description

The invention relates to a method for manufacturing a film web having an Al-Zn layer with a pressure-tight lockable housing, in which a winding system for taking up and moving on a film web especially provided for capacitors is, as well as a first provided in the housing and second evaporation source for that to be evaporated Medium.

It is well known to mix Al-Zn layers on paper and plastic films or on films for capacitors by vapor deposition of aluminum and zinc. For this purpose, a moving, ribbon-shaped substrate is running in a film coating chamber, in such a way that degassing and coating independently expire and that separate vacuum pumping stations for both purposes be used. In the preparation of a mixed layer, the substrate is cooled over a Roller guided and one atmosphere at a time of Al steam and Zn steam or Zn steam and Al steam exposed. The evaporation of Zn and Al takes place from separate evaporator sources. The most important part or the main component of this mixed layer represents Zn. Layers produced in this way corrode very quickly on contact with oxygen, so that  the films their favorable after a longer storage period Lose properties; even if they're already in Capacitors have been processed, the Dielectric constant and the loss angle disadvantageous change.

Furthermore, a method (PCT WO 88/0098) for Make a silver-copper layer having film sheet with a pressure-tight closable housing known in which a Wrapping system for taking up and moving the Foil sheet is provided for capacitors. For this are in a housing for evaporation sources evaporating means provided.

Furthermore, according to another method, it is known (De 26 41 232 A1) to produce a thin film combination, why during the transport to the substrate surface Aluminum atoms with residual oxygen or Residual water react so that aluminum oxide is formed becomes.

Accordingly, the object of the invention is to provide foils, in particular to produce foils for capacitors, that they are less prone to corrosion and even after a long storage period their original Maintain properties. In the known methods can not the corrosion behavior improve. None of the known methods exist for this a hint.

The invention solves the problems in that Foil sheet aluminum and zinc evaporated and simultaneously oxygen is added in a targeted manner.  

This will add the reactive gas in making a single layer on simple Way the long-term behavior of the metal-coated Foil significantly improved and corrosion of the Film almost completely after its metallization excluded or reduced to a minimum, so that a capacitor with one manufactured in this way No film material even after its completion more changes its dielectric properties. A Corrosion is excluded even if the metallized film comes out of the vacuum and with Oxygen comes into contact. This will be simple Way achieved in that in the metallization process Oxygen is metered into the mixed layer.

This also makes it possible to always use capacitors to manufacture smaller and the manufacturing tolerances of To reduce capacitors down. To capacitors today To be able to manufacture inexpensively Checks for breakdown of the capacitors to reduce a minimum. That is why they are with one special glue applied to circuit boards. Purpose of Invention is therefore, among other things, circuit boards for To develop capacitors that no longer adjust Need to become. This also results in very tight manufacturing tolerances for the individual components. Further can now the capacity, for. B. the loss angle and the dielectric constant of the capacitors, at the beginning the production is defined much more precisely or be determined than before.

After finishing making the film for one The capacitor is still exposed to oxygen  and can by the layer treatment according to the invention no longer corrode, so the dielectric Properties of the film remain unchanged. A capacitor manufactured and encapsulated changes hence its property or capacity after a long storage period, so that one with printed circuit board manufactured in this way can fully perform its specified task.

For this purpose it is advantageous that the proportion of Al at the production of the Al-Zn mixed layer or at Evaporation process between 0.5 and 20 wt .-% large and the degree of oxidation of the oxygen taken in is between 1 and 25%.

It is also advantageous that the coating roller clockwise or counterclockwise is driven such that either Al or Zn and then the second layer Zn or Al on the Foil sheet is evaporated, with oxygen during of the vapor deposition process of Zn and / or of Al becomes.

In connection with the training according to the invention and arrangement it is advantageous that the amount of evaporation (nm / s) of Zn is larger than the amount of vapor deposition (nm / s) of Al.

It is also advantageous that the thickness of the electrical conductive layer of the film during the coating process Oxygen was added between 30 nm and Is 50 nm in size.  

Further advantages and details of the invention are in the claims and explained in the description and shown in the figures, it being noted that  all individual characteristics and all combinations of individual characteristics are essential to the invention. It shows

Fig. 1 is a side view of a coil-coating line with a filament winding and many guide rollers for the film web in section,

Fig. 2 shows a mixed layer produced by the method.

In Fig. 1, an apparatus and a method for manufacturing the Al-Zn layer having film web 40 is shown, to which belongs the pressure-tight sealable housing in which a winding system 29 is provided for receiving and moving the film web 40 and in particular for capacitors.

The housing of the coil coating system 1 essentially consists of deflection, stretching and tensioning rollers 7 to 13 mounted between two side parts 2, 4 and a cooled coating roller 18 . Furthermore, the coil coating system 1 has an unwinding or substrate roll 37 , a winding or substrate roll 35 , a coating chamber 28 , a first evaporation source 19 for Al and a second evaporation source 20 for Zn, each with an evaporator 21, 21 ' . The evaporator 21 for Al can be designed as an evaporator boat, while the evaporator 21 ' for Zn can have a specially designed nozzle. A winding device 29 is provided in an upper chamber half 26 .

In the method shown in FIG. 1, the rollers 7 to 13 for transporting and guiding the film web 40 are arranged in such a way that the section of the film web 40 which is located directly in front of the coating roller 18 is at a steep angle, ie almost perpendicular runs down from rollers 7 to 9 . It is also possible to run this part of the film web 40 differently; for example, it can run in an approximately horizontal plane. The film web 40 moves past the evaporation sources 19, 20 according to arrow 39 .

The aluminum layers applied using a PVD process (physical vapor deposition and dusting) have good electrical conductivity, great reflectivity and good adhesion. In addition, since aluminum is inexpensive, it can easily be provided in large quantities, and the Al wire can be evaporated in the evaporator 21 at low temperatures. Aluminum is evaporated by parallelepiped-shaped evaporation sources 19 heated by direct current passage as shown in the drawing.

Because of the layer thickness uniformity, several evaporation sources can be arranged side by side over the entire film width. The distance between two neighboring sources is approximately 100 mm. In the exemplary embodiment according to FIG. 1, the evaporation source 19 or the evaporator 21 is provided for Al and, at a distance from it, the evaporation source 20 or the evaporator 21 ' for Zn; a partition 22 is provided between the evaporation sources 19, 20 .

The desired layer thickness is at feed rate by appropriate coordination of belt speed and the amount of exhaust steam set per unit of time. Each evaporation source has its own supply, being deviations in the electrical behavior of each Evaporators are balanced. The evaporation material is the same with the individual sources Feed speed fed.

Fig. 1 shows only the schematic structure of the group consisting of a lower and upper chamber 25, 26 formed coating chamber 28 of the coil coating line and the winding device 29.

On the web of film 40 first Cu or Ag is vapor-deposited for better condensation of Zn on the foil web 40, then zinc and subsequently aluminum. At the same time, targeted doses of oxygen are added. The oxygen can be metered in via a control or regulating device, which detects the amount of evaporation at the evaporation sources 19, 20 via a transmitter and forwards the determined controlled variable to an evaluation unit.

The advantage of the capacitor foils 40 produced in the coating chamber 28 is that they have, among other things, a so-called self-healing effect. Finally, indestructibility of the capacitor is very important in some applications, ie oxidation layers form at damaged areas, by which the short circuit is eliminated by itself. In the event of a short circuit (ie energy supply), the metal layer evaporates at this point and the insulation of the capacitor is restored.

Oxygen is admitted into the vapor space 17 of the Al evaporation source 19 via a gas inlet system 14 . This advantageously creates a mixture of Al + Al₂O₃. The degree of oxidation of Al by adding oxygen is between 1 and 25%. By installing Al₂O₃ in the Al-Zn mixed layer, the corrosion resistance of the layer to water vapor is significantly improved.

The thickness of the electrically conductive layer is between 1 and 2 nm. For aluminum this corresponds to one Layer thickness of about 30 to 50 nm.

The Al content can be between 0.5 and 20% of the total layer turn off. By regulating the Al and / or Zn evaporation rate, which is then a function of the overall layer is set, the layer composition can be constant being held.

Subsequent corrosion tests of the Al-Zn mixed layer have achieved very good results. To control the Corrosion resistance was tested in a climatic chamber under a temperature of 40 ° C, one relative humidity of 92% over a period of eight entered up to sixteen hours. The rehearsals were on stretched over a frame, so that when the Samples no water on the in the climate cabinet Could condense film surface. The heating process took place at a temperature of 30 ° C without additional Humidification. Then the described Process parameters set. The break-in period was about thirty minutes. By the simultaneous Start up or adjust the test chamber and the  Samples on the required process parameters could Condensation during the process of introducing the samples into the Chamber to be avoided. After completing the corrosion test the corrosion resistance was checked and found that there was no corrosion on the metal layer had occurred.

The measurement of the surface resistance of the sample before and after storage in a climatic cabinet, a Four point measurement. Examination of the sample by Inspection revealed no visible holes or Openings (pinholes). Improving corrosion resistance this leads to a significant improvement of the sheet resistance.

The test results clearly show that by dosed or regulated oxygen supply an essential one in the vapor space of the Al and / or Zn evaporator Improve the corrosion properties of the Foil and favorable influence on the surface resistance was achieved in a very cost effective manner. By the The oxidation rate lies in the method according to the invention between 5 and 50%.

Reference list

1 coil coating line
2 side part
4 side part
7 Deflection, stretching and tensioning roller
8 deflection, stretching and tensioning roller
9 Deflection, stretching and tensioning roller
14 Inlet system for oxygen
17 steam room
18 coating roller
19 Evaporation source Al; Al evaporator
20 evaporation source Zn; Zn evaporator
21, 21 ′ evaporator
22 partition
25 lower half of the chamber
26 upper chamber half
28 coating chamber
29 winding device, winding system
35 take-up roll or substrate roll
37 Unwinding roll or substrate roll
39 arrow
40 film web

Claims (16)

1. A method for producing an Al-Zn layer having a film web ( 40 ) with a pressure-tight sealable housing, in which a winding system ( 29 ) for receiving and moving the film web ( 40 ) is provided, in particular for capacitors, and one provided in the housing first and second evaporation source ( 19, 20 ) for the agent to be evaporated, characterized in that aluminum and zinc are vapor-deposited on the film web ( 40 ) and at the same time oxygen is added in a targeted manner. 2. The method according to claim 1, characterized in that that the proportion of Al in manufacturing from the Al-Zn mixed layer or during the vapor deposition process between 0.5 and 20% by weight is and the degree of oxidation of the admitted Oxygen is between 1 and 25%. 3. The method according to one or more of the preceding claims, characterized in that the coating roller ( 18 ) is driven clockwise or counterclockwise in such a way that either first Al or Zn and then the second layer Zn or Al on the film web ( 40th ) is evaporated, with oxygen being added during the vapor deposition process of Zn and / or Al. 4. Method according to one or more of the preceding Claims, characterized in that the vapor deposition amount (nm / s) of Zn is greater than the evaporation amount (nm / s) of Al. 5. The method according to one or more of the preceding claims, characterized in that the thickness of the electrically conductive layer of the film ( 40 ) to which oxygen was added during the coating process is between 30 nm and 50 nm. 6. The method according to one or more of the preceding claims, characterized in that during the evaporation process the belt speed of the film ( 40 ) is set between 1 and 10 m / sec. 7. The method according to one or more of the preceding claims, characterized in that the vapor-coated film web ( 40 ) is only partially coated or has non-vaporized strips. 8. Method according to one or more of the preceding claims, characterized in that the unevaporated parts of the film web by means of a tape or oil mark. 9. The method according to one or more of the preceding claims, characterized in that the be evaporated onto the film web (40) layer or layers by vapor deposition in stripes on the film web (40), the strips having at the center a thickness greater than the Edges of the evaporated strips. 10. The method according to one or more of the preceding claims, characterized in that the thicker strips are applied by means of a nozzle system of the Zn evaporator ( 20 ). 11. The method according to one or more of the preceding claims, characterized in that the first vapor-deposited layer on the film ( 40 ) consists of a Zn layer and the second layer consists of an Al + Al₂O₃ layer, wherein for pre-germination of the substrate or the film ( 40 ) Ag or Cu is evaporated on the surface of the substrate. 12. The device according to one or more of the preceding claims, characterized in that an inlet system ( 14 ) for oxygen is provided in the region of the first evaporation source ( 19 ), which is controllable via an actuator depending on the amount of evaporator, and that the first evaporation source ( 19 ) and the inlet system ( 14 ) is shielded by a partition ( 22 ) from the second evaporation source ( 20 ). 13. The device according to one or more of the preceding claims, characterized in that a partition ( 22 ) is provided between the Al evaporator ( 19 ) and the Zn evaporator ( 20 ). 14. The device according to one or more of the preceding claims, that the first evaporation source ( 19 ) for Al is provided between the inlet system ( 14 ) for oxygen and the partition ( 22 ). 15. The device according to one or more of the preceding claims, characterized in that the inlet system ( 14 ) for oxygen in the region of the first and / or the second evaporation source ( 19, 20 ) for Al and / or Zn is provided. 16. A film web according to the method according to one or more of the preceding claims, characterized in that the mixed layer evaporated on the film ( 40 ) consists of a Zn layer and a second Al + Al₂O₃ layer, the Al content between 0, 5 and 20 wt .-% is.