WO2015067464A1

WO2015067464A1 - Transport device for flat substrates

Info

Publication number: WO2015067464A1
Application number: PCT/EP2014/072542
Authority: WO
Inventors: Stefan Rapp
Original assignee: Gebr. Schmid Gmbh
Priority date: 2013-11-11
Filing date: 2014-10-21
Publication date: 2015-05-14
Also published as: DE102013222937A1; TWI635032B; TW201532921A

Abstract

The invention relates to a transport device for flat substrates, in particular for transporting printed circuit boards and similar electronic substrates or electrical engineering substrates, such as structured and unstructured semiconductor wafers and thin-layer components used in electronics and electrical engineering. The transport device has one or preferably more transport rollers (1) which are arranged one behind the other in a transport direction and/or at least one pair of which is arranged one over the other perpendicularly to a transport direction and between which a substrate transport gap (5) is formed. Each transport roller contains a shaft (2) and a substrate contact region (4') which is rotationally fixed to the shaft. Furthermore, the transport device comprises an advancing support (6) with sliding bearings (9), in which a respective end-face journal (10) of each transport roller is rotatably supported on one side or preferably on both sides. According to the invention, the transport roller substrate contact region (4') and a sliding bearing region (8) of the advancing support consist of an electrically conductive plastic material. Additionally, the transport device has an electric discharge path to which the transport roller substrate contact region and/or the advancing support sliding bearing region is connected in an electrically conductive manner. The invention also relates to the use of said transport device for example for transporting printed circuit boards in the production of printed circuit boards.

Description

Transport device for flat substrates

The invention relates to a transport device for flat substrates, in particular for the transport of printed circuit boards and similar electronic substrates or electrical engineering substrates, such as structured and unstructured semiconductor wafers and thin-film components used in electronics and electrical engineering. The transport device has one or preferably a plurality of transport rollers, which are arranged one behind the other in a transport direction and / or of which at least two are arranged as a pair perpendicular to a transport direction one above the other and form a substrate transporting gap between them. The respective transport roller includes a shaft and a substrate contact area which is non-rotatable with the shaft. Furthermore, the transport device comprises a feed carrier with plain bearings, in which the respective transport roller is rotatably mounted on one side or preferably on both sides with a respective end-side shaft journal.

Such transport devices are common in various designs. Thus, published patent application DE 101 28 386 A1 discloses a transport device of this type, in which the slide bearings for the transport rollers are specially formed by inserts which are interchangeable inserted into corresponding receptacles of the feed carrier. The shafts of the transport rollers are typically made of titanium, stainless steel or polytetrafluoroethylene (PTFE). The feed carrier with the slide bearings is typically made of a plastic material such as polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC) or polyvinylidene fluoride (PVDF). For printed circuit boards and similar substrates there is often a need or requirement to protect them from electrostatic charges. In transport routes, in which the substrates undergo a treatment with a liquid, this usually prevents such unwanted electrostatic charges. On transport routes without liquid treatment, this protection mechanism is not given. Such "dry" transport lines are, for example, typical run-in modules, control modules, drying modules and run-off modules of modular substrate treatment systems.

It is known to counteract electrostatic charges in such dry transport routes by the use of an ion spray bar above and / or below the substrate transport plane. Such ionic spray bars, however, can not be permanently used under some environmental conditions, such as those found in printed circuit board processing, such as in ambient air polluted with chemicals and in elevated temperature environments, such as prevalent in drying modules. Although the substrates could also be protected from electrostatic charging by the fact that the transport rollers are made metallic not only with their wave, but also with their substrates contacting the substrate contact area, but this can easily lead to damage to the surface of the substrates, which for example in circuit boards radio - Can cause breakdown losses due to damage to their fine interconnect structures. In addition, typically used for transport rollers metallic materials such as stainless steel or titanium, due to their limited chemical resistance for use in printed circuit board production facilities are only partially suitable.

The invention is based on the technical problem of providing a transport device of the type mentioned above, with which transported flat substrates, such as printed circuit boards, can be protected during the transport in an improved manner from electrostatic charges.

The invention solves this problem by providing a transport device having the features of claim 1. In this transport device, the transport roller substrate contact area and the slide bearing area of the feed carrier consist of an electrically conductive plastic material. In addition, an electrical discharge path is provided, with which the transport roller substrate contact region and / or the feed carrier plain bearing region is electrically conductively connected.

In this way, the transport device according to the invention ensures sufficient discharge of electrical charges from the transported flat substrates or from the transport rollers and the feed carrier via the electrical discharge path, so that no undesirable electrostatic charges can form which lead to damage of the substrates could. Charges in the slide bearing area of the feed carrier can be removed directly without reaching the substrates. Charges that form in the contact area of the transport rollers with the substrates can be removed via the transport rollers and the feed carrier. The substrates are contacted by the existing of electrically conductive plastic material substrate contact area of the transport rollers, whereby contact of the transported substrates with metallic transport roller areas is avoided.

In one development of the invention, the electrically conductive plastic material for the transport roller substrate contact region or the feed carrier plain bearing region is an electrically conductive PP material or PE material or PVDF material or polyetherketone material. ton (PEEK) material. These materials have proven to be well suited for the present purpose.

In one development of the invention, the electrically conductive plastic material for providing the desired electrical conductivity includes a preferably particulate introduced filler made of a carbon black or graphite or palladium material.

In one development of the invention, the electrical discharge path is designed for an ohmic leakage resistance in the range from 0.1 Ω to 2 Ω. Thus, the electrical discharge path provides a defined high-resistance electrical resistance, as it is particularly suitable for the targeted derivation of possibly occurring, unwanted electrostatic charges.

In a further development of the invention, the shaft of the respective transport roller is formed from a metal material, which may in particular be a stainless steel material.

In a further development of the invention, the feed carrier includes a metallic base body and a slide bearing insert attached thereto, which comprises the sliding bearing region of the feed carrier and accordingly consists of the conductive plastic material provided for this purpose.

In a further development of the invention, the feed carrier on a metallic rail which is electrically connected to the sliding bearing region of the respective transport roller and is electrically connected to a discharge line. The metallic rail can thereby serve as current busbars of the electrical discharge path, with which in the case of multiple transport rollers, the electrostatic charges of these transport rollers or their sliding bearings can be collected collected to the discharge line. In addition, the metallic rail can fulfill a mechanical stabilization function for the feed carrier.

Advantageous embodiments of the invention are illustrated in the drawings and will be described below. Hereby show:

1 is a fragmentary plan view of a printed circuit board transport device with several in the transport direction one behind the other and transversely to the transport direction in pairs stacked transport rollers,

2 is a sectional view taken along a line I II I of Fig. 1, 3 is a sectional view taken along a line II II II of Fig. 1,

4 is a plan view corresponding to FIG. 1 for a variant of the transport device of FIG.

1 to 3 and

Fig. 5 is a sectional view taken along a line VV of Fig. 4. Figures 1 to 3 show a transport device with which printed circuit boards or similar flat substrates, such as those used in the electronics industry and the electrical industry, along a transport direction T. one example transport horizontal transport route. For this purpose, the transport device has a plurality of transport rollers 1, which can be designed to be identical or different from one another as required. In the example shown, the latter is the case. In the sectional view of Fig. 1 to 3, a pair of transport rollers 1 a of a roll type and a pair of transport rollers 1 b of a cylinder type can be seen, wherein the two pairs of rollers in the transport direction T are arranged one behind the other and the two transport rollers of the respective pair perpendicular to the transport direction T are arranged one above the other. All transport rollers 1 a, 1 b are arranged with mutually parallel longitudinal axes.

The transport rollers 1 a roll type include a shaft 2, on the axial distance from each other a plurality of rollers 3 is rotatably held. In the case of the cylinder-type transport rollers 1b, a roll cylinder 3 'is fixedly held on the shaft, whose lateral surface 4 forms a substrate contact region with which these transport rollers 1b contact the substrates and transport them by the rolling rotational movement. In the transport rollers 1 a of the roller type, the substrate contact area is formed by a peripheral surface 4 'of the rollers 3. As can be seen from FIGS. 2 and 3, the respective paired transport rollers 1 a, 1 b of roller type or cylinder type form between them a substrate transporting gap 5 through which the substrates are transported in the transport direction T, for which purpose the two transport rollers 1 each pair in opposite directions and at the same height in the transport direction T consecutive transport rollers 1 rotate in the same direction.

For storage and to drive the transport rollers 1, the transport device has a feed carrier, which includes two lateral feed carrier units 6a, 6b on the sides of the transport rollers 1 in the example shown. The respective feed carrier unit 6a, 6b has a base body 7 which extends parallel to the transport direction T longitudinally below the transport rollers T and has plain bearing regions 8 projecting upwards perpendicularly to the transport direction and to the transport roller longitudinal axes. The respective plain bearing area 8 includes plain bearings 9, in which the shafts 2 of the transport rollers 1 are rotatably held with a respective shaft end or shaft journal 10.

On one side, here on the right side in FIGS. 1 to 3, on which the feed carrier unit 6a is located, the feed carrier 6 comprises a roller drive 1 1 of a conventional design with a drive shaft passing through in the transport direction, to the bevel gear the individual transport rollers 1 are coupled.

Furthermore, the transport device includes an electrical discharge path to which the transport roller substrate contact regions 4, 4 'and the feed carrier plain bearing regions 8 are electrically conductively connected. Alternatively, e.g. Also, only the plain bearing areas 8 to be electrically coupled to this discharge path. The discharge path includes one each of the respective feed carrier unit 6a, 6b laxative electrical discharge line 12a, 12b, which is mounted by means of an associated screw electrically contacting the feed carrier unit 6a, 6b. In the example shown, a continuous, electrically conductive and preferably metallic rail 13a, 13b is mounted in the lower region of the feed carrier unit 6a, 6b with electrical contact to the same and to the discharge line 12a, 12b with the same screw connection. The two rails 13a, 13b have a mechanical stabilizing function for the respective feed carrier unit 6a, 6b and serve as a busbar for discharging electrical charges from the plain bearing areas 8, which are assigned to the various transport rollers 1, to the associated discharge line 12a, 12b.

The peripheral surfaces 4 'of the roller rollers 3, which act as a substrate contact region, consist of an electrically conductive plastic material, preferably a PP material, a PVDF material or a PEEK material, which is made of carbon black, graphite or palladium material through a particle filler is made electrically conductive in a desired, predeterminable degree. Depending on requirements and application, the rollers 3 can also be made of this electrically conductive plastic material otherwise. Likewise, the cylinder surface of the transport rollers 1 b functioning as a substrate contact region consists of such an electrically conductive and preferably thermoplastic plastic material, again depending on requirements and application, the cylinder part of these transport rollers 1 b also made of this electrically conductive plastic material or alternatively of another material consists. The shafts 2 of the transport rollers 1 are preferably made of precious metal or other metal material. It is understood that the shafts 2 may alternatively consist of one of said electrically conductive plastic materials, if appropriate. Likewise, the plain bearing areas 8 of the feed carrier 6 are made of an electrically conductive plastic material, in particular one of the materials mentioned above. Preferably, an electrically conductive PE material or PEEK material is used here. The use of PEEK material is preferably limited to the sliding bearing region 8, while the feed carrier 6, moreover, ie its base body 7, is then preferably made of a metallic material, eg a titanium or stainless steel material. Alternatively, the feed carrier base body 7 may consist of the electrically conductive plastic material used for the sliding bearing region 8, wherein then also an integral realization of the respective feed carrier unit 6a, 6b is possible. The use of PEEK material is particularly useful for applications where relatively high ambient temperatures occur, such as in drying modules where ambient temperatures of, for example, up to 90 ° C prevail.

In each of the mentioned embodiments, it is ensured that there is a sufficient continuous electrical connection from the transport roller substrate contact areas 4, 4 'to the discharge lines 12a, 12b for discharging any electrostatic charges. The relevant electrical discharge path is in this case preferably designed for an ohmic leakage resistance in the range of 0.1 Ω to 2 Ω, which is accomplished in particular by appropriate adjustment of the electrical conductivity of the one or more electrically conductive plastic materials used. In this way, it is reliably avoided in the transport device that the substrates or printed circuit boards transported by it are exposed to excessive electrostatic charges when such charges in the contact area of the rollers 1 to the substrates and in the sliding bearing areas 8 of the rotating operation of the transport rollers 1 Feed carrier units 6a, 6b form. Such electrostatic charges are discharged reliably in the transport device according to the invention via the electrical discharge path and the discharge lines 12a, 12b.

Figs. 4 and 5 illustrate a variant of the transport device of Figs. 1 to 3, wherein the same reference numerals are used to facilitate understanding of identical and functionally equivalent elements and insofar reference can be made to the above description of the transport device of Figs. 1 to 3.

The transport device of FIGS. 4 and 5 differs from that of FIGS. 1 to 3 above all in that the slide bearing regions 8 of the two feed carrier units 6a, 6b are manufactured as separate components from the respective main body 7 and as sliding bearing inserts into corresponding receptacles of the feed carrier units 6a, 6b are used. This leaves a simple one Material decoupling of the sliding bearing areas 8 on the one hand and the base body 7 on the other hand and allows easy replacement of the wear-susceptible sliding bearing areas 8 while maintaining the body 7. The main body 7 may be made in this case, for example, from a stainless steel material, while the Gleitkörpereinsätze if necessary electrically conductive PEEK material can be made.

By the above-mentioned choice of suitable materials for the various mentioned components of the transport device can also be ensured that all device components have the required chemical resistance and temperature resistance, which is required for these different device components depending on the application.

It is understood that in alternative embodiments, the transport device according to the invention may include a different number and arrangement and a different design of the transport rollers, depending on the nature of the substrates to be transported and the place of use or the environmental conditions. In any event, however, there is an electrical discharge path through which electrostatic charges in the transport roller substrate contact area and / or in the slide carrier journal area can be reliably dissipated and thereby avoided without, on the other hand, being at the expense of reduced chemical or thermal resistance of the device.

Claims

claims

1 . Transport device for flat substrates, in particular printed circuit boards, with

- One or more arranged in a transport direction successively transport rollers (1) and / or at least one pair of transversely to a transport direction arranged one above the other, a substrate transporting gap forming transport rollers (1), wherein the respective transport roller a shaft (2) and one with the Shaft rotationally fixed substrate contact region (4, 4 '), and

- A feed carrier (6) with plain bearings (9), in which the respective transport roller is rotatably mounted with an end-side shaft journal (10),

d a d u r c h e s e n c i n e s, d a s s

- The transport roller substrate contact area (4, 4 ') and a sliding bearing area (8) of the feed carrier (6) made of an electrically conductive plastic material and

an electrical discharge path is provided, to which the transport roller substrate contact area and / or the feed carrier plain bearing area is electrically conductively connected.

2. Transport device according to claim 1, further characterized in that the electrically conductive plastic material is an electrically conductive PP material or PE material or PVDF material or PEEK material.

3. Transport device according to claim 1 or 2, further characterized in that the electrically conductive plastic material contains an electrically conductive filler of carbon black or graphite or palladium material.

4. Transport device according to one of claims 1 to 3, further characterized in that the electrical discharge path is designed for an ohmic leakage resistance in the range of 0.1 Ω to 2 Ω.

5. Transport device according to one of claims 1 to 4, further characterized in that the shaft of the respective transport roller of a metal material, in particular stainless steel, is formed.

6. Transport device according to one of claims 1 to 5, further characterized in that the feed carrier comprises a base body (7) made of a metal material, in particular special stainless steel, and a mounted on the base body, the sliding bearing area containing slide bearing insert (8) made of the conductive plastic material.

Transport device according to one of claims 1 to 6, further characterized in that the feed carrier has a metallic rail (13a, 13b) which is electrically connected to the sliding bearing region of the respective transport roller and to which a discharge line is electrically connected.