PRINTED CIRCUIT BOARD FOR AN AUTOMATION FIELD DEVICE

Abstract

Circuit board for a field device of automation technology comprising a plurality of electronic components (4) and a potting compound container (2) made of a plastic and having a peripheral side wall defining an outer contour of the potting compound container, a potting compound cover adjoining the side wall and an opening located on the potting compound cover far side, wherein the potting compound container is set via the opening over at least a part of the plurality of electronic components (4) and filled with a potting compound in such a manner that electronic components covered by the potting compound have a predetermined, or defined, minimum covering, wherein the potting compound container is, however, not completely filled with potting compound and wherein in the potting compound cover in an edge region, which borders a transition from the side wall to the potting compound cover, at least one gap is present, which extends at least over a convex edge region of the outer contour.

Claims

1-10. (canceled)

11. A circuit board for a field device of automation technology comprising a plurality of electronic components and a potting compound container made of a plastic and having a peripheral side wall defining an outer contour of the potting compound container, a potting compound cover adjoining the side wall and an opening located on the potting compound cover far side, wherein the potting compound container is set via the opening over at least a part of the plurality of electronic components and filled with a potting compound in such a manner that electronic components covered by potting compound have a predetermined, or defined, minimum covering, wherein the potting compound container is, however, not completely filled with potting compound and wherein in the potting compound cover in an edge region, which borders a transition from the side wall to the potting compound cover, at least one gap is present, which extends at least over a convex edge region of the outer contour.

12. The circuit board as claimed in claim 11, wherein a breadth of the at least one gap is such that the at least one gap has a minimum gap breadth of at least 0.5 mm.

13. The circuit board as claimed in claim 11, wherein a breadth of the at least one gap is such that the at least one gap has a maximum gap breadth of no more than 6 mm.

14. The circuit board as claimed in claim 11, wherein a length of the at least one gap is such that the at least one gap extends at least over a convex edge region of the outer contour.

15. The circuit board as claimed in claim 11, wherein the potting compound container has in the potting compound cover a plurality of gaps located, in each case, in the edge region.

16. The circuit board as claimed in claim 15, wherein the number of gaps in the edge region of the potting compound cover is such that they extend completely along the outer contour and are only interrupted by at least one land.

17. The circuit board as claimed in claim 16, wherein the at least one land has a minimum width of at least 0.5 mm.

18. The circuit board as claimed in claim 11, wherein the one or more gaps are formed by an injection molding method, a blanking method, a milling method or a laser cutting method.

19. The circuit board as claimed in claim 11, wherein the predetermined, or defined, minimum covering results from the standard, DIN EN60079-11, published June 2012, Explosion Atmospherespart 11: Equipment Protection by Intrinsic Safety i and/or amounts preferably to 1 mm.

20. A field device of automation technology, including: a circuit board for a field device of automation technology comprising a plurality of electronic components and a potting compound container made of a plastic and having a peripheral side wall defining an outer contour of the potting compound container, a potting compound cover adjoining the side wall and an opening located on the potting compound cover far side, wherein the potting compound container is set via the opening over at least a part of the plurality of electronic components and filled with a potting compound in such a manner that electronic components covered by potting compound have a predetermined, or defined, minimum covering, wherein the potting compound container is, however, not completely filled with potting compound and wherein in the potting compound cover in an edge region, which borders a transition from the side wall to the potting compound cover, at least one gap is present, which extends at least over a convex edge region of the outer contour.

Description

[0028] The invention will now be explained in greater detail based on the appended drawing, the figures of which show as follows:

[0029] FIG. 1 a schematic view of a cross section of a circuit board for a field device of automation technology, populated with electronic components and potted by means of a potting compound container of the invention containing a potting compound, and

[0030] FIG. 2 an example of an embodiment of a potting compound container of the invention.

[0031] FIG. 1 shows a schematic view of a cross section of a circuit board 1 for a field device of automation technology, populated with electronic components and potted by means of a potting compound container of the invention containing a potting compound. Circuit board 1 can comprise a plurality of electronic components 4, at least, however, one electronic component, potted by means of a potting compound. The electronic components 4 can be, for example, SMD (Surface Mounted Device) components, which are mounted on the circuit board 1 in an SMD process. The electronic components 4 can be set on the circuit board 1, for example, using an automatic pick-and-place machine. For this, solder paste and/or adhesive 5 are/is first placed on the circuit board 1 at the appropriate positions, where the electronic components 4 are to be applied, and then the electronic components 4 are soldered in place and in given cases, supplementally adhered. Additionally, solder paste and/or adhesive 5 can also be provided, where the potting compound container 2 is to be provided later, in order that such can later also be mechanically secured, and held permanently.

[0032] The potting compound container 2 is a plastic potting compound container 2 for placement over the electronic components. Potting compound container 2 includes a surrounding side wall 2c and a container cover 2d, which adjoins the side wall 2c. On a container cover 2d far side, the potting compound container is open, such that it can be set via the open side on the circuit board 1 over the electronic components to be potted.

[0033] In order to enable a filling of the potting compound container 2 after its placement on the circuit board 1, at least one filling opening 2a is provided in the potting compound container 2, via which the potting compound 3 can be fed in. To aid in this, at least one air escape opening 2b can be provided in the potting compound container 2.

[0034] Potting compound container 2 is filled with a potting compound 3, wherein the potting compound container is not completely filled with potting compound 3, but, instead, only to the extent that each electronic component under the potting compound container has at least a minimum covering d.sub.min of potting compound. In such case, the minimum covering d.sub.min is governed by the standard, DIN EN60079-11, published June 2012, Explosive AtmospheresPart 11: Equipment Protection by Intrinsic Safety i. For example, the minimum covering can amount to 1 mm, such that all electronic components are covered by at least 1 mm thickness of potting compound.

[0035] FIG. 2 shows a potting compound container 2 of the invention, in which there are a plurality of gaps 2e in the cover 2d. The gaps 2e serve to suppress capillary action, such that the potting compound 3 can only reach the gaps 2e at the side wall 2c. The gaps 2e are, in such case, preferably arranged in the edge region of the cover 2d at the transition to the side wall 2c of the potting compound container 2. Ideally, the gaps 2e are arranged directly at the transition from the side wall 2c to the potting compound cover 2d. The minimum separation, in such case, is limited only by the method by which the gaps are produced.

[0036] As regards the breadth B.sub.gap of the gaps, such is selected such that the minimum gap breadth is at least 0.5 mm, preferably at least 1 mm, especially preferably greater than or equal to 2 mm and/or the maximum gap breadth is not greater than 6 mm, preferably not greater than 5 mm, especially preferably not greater than 4 mm. As regards the length L.sub.gap of the gaps, such is preferably selected in such a manner that the gaps 2e extend, in each case, at least over a convex edge region of the outer contour, such as, for example, a corner, of the potting compound container, such as shown in FIG. 2 by a dashed arrow. In a special embodiment, the gaps 2e are formed in the cover 2d in such a manner that they extend essentially along an outer contour of the side wall of the potting compound container 2. This means that the individual gaps form virtually a peripheral gap, which is interrupted only by at least one land. For stability of the cover, however, also more than one gap, for example, at least two or at least three gaps, can be present, e.g. the peripheral gap can be interrupted by spaced lands 2f.

[0037] The lands 2f serve, in such case, for mechanically stabilizing the cover 2d, such that the cover 2d offers, on the one hand, a certain protection against mechanical effects, and, on the other hand, the gap, e.g. the almost complete peripheral gap, prevents migration of the potting compound. Mechanical effects can arise, for example, during installation and/or replacement of the prefabricated circuit board in a field device.

[0038] The one or more gaps 2e can be formed, for example, directly during the manufacturing of the potting compound container 2, in that they are correspondingly provided for in an injection molding tool/die for the potting compound container 2. Alternatively, the gaps 2e can also be introduced into the potting compound container 2 after the molding of the potting compound container 2, for example, as a result of milling, blanking or by means of a laser.

LIST OF REFERENCE CHARACTERS

[0039] 1 circuit board [0040] 2 potting compound container [0041] 2a filling opening [0042] 2b air escape opening [0043] 2c side wall of the potting compound container [0044] 2d cover of the potting compound container [0045] 2e gap(s) [0046] 2f land(s) [0047] 3 potting compound [0048] 4 electronic components [0049] 5 solder paste [0050] d.sub.min minimum covering [0051] B.sub.gap breadth of the gap [0052] L.sub.gap length of the gap