T 0914/21 (Brazing sheet/UACJ) 16-03-2023

1. Consideration of new arguments

In response to the board's communication under Rule 15(1) RPBA 2020, the respondent submitted a number of new arguments. The appellant requested that they not be considered.

However, since all the claim requests fail anyway, the question of their consideration can be left unanswered.

Main request

The main request corresponds to the patent as granted.

2. Article 123(2) EPC

2.1 To a great extent, claim 1 of the main request is based on claims 2 to 5 as originally filed.

However, as compared with claim 2 as originally filed, claim 1 of the main request relates to "[a]n aluminum-alloy brazing sheet ... consisting of [deleted: having] a core and a filler material clad to one side or both sides of the core".

For the reasons set out below, this amendment is not directly and unambiguously derivable from the application as originally filed, contrary to the opposition division's view.

2.2 It has not been disputed that the wording "consisting of" is not explicitly present in the application as originally filed in the context of the constituent parts of the brazing sheet. Indeed, both the initial and the corrected versions of the translation of the application as originally filed (in Japanese) merely disclose the brazing sheet as "having" a core and a filler material clad to one side or both sides of the core (claim 2, see also paragraphs [0018] and [0019]). This means that further layers/elements are not excluded.

2.3 In the respondent's view, the combination of claim 2 with paragraph [0007] as originally filed justified the replacement of "having" by "consisting of", in particular since the remaining original disclosure also does not mention or imply an additional layer.

However, this is not convincing.

Firstly, the disclosure of paragraph [0007] relates to two prior-art documents and does not indicate that the inventive brazing sheet must not comprise additional layers or elements, i.e. besides the core and the filler material (the latter being on one or on both sides of the core).

Even if it were considered, for the sake of argument, that paragraph [0007] also had consequences for the invention, this passage only indicates that a quite specific additional layer has drawbacks, namely "a thin film" on the filler-material surface that is "composed of a metal having a melting point higher than that of the filler material". This paragraph does not in any way exclude, for example:

- a layer between the core and the filler material (such as the "interlayer" of claim 1 of D8/D8WO)

- a layer on the opposite side of the core in the case of a filler material that is present only on one side of the core, e.g. a sacrifical (anode) layer

- a layer on the same side as the filler material but different from the specific layer disclosed in paragraph [0007].

2.4 For the sake of completeness, neither the exemplary embodiments nor Figure 1 of the application as originally filed hint at the new feature.

- Embodiments 61 and 62 (Table 3 on page 26) are the only embodiments that fulfil the requirement of claim 1 that the core contain "at least one of Si, Fe, Cr, Zn or Ti". While it is true that these embodiments do not mention further layers besides a core and a filler material, further features are disclosed in combination. For example, the filler material is clad to only one side of the core (see paragraph [0076] and the last lines of paragraph [0054]). Moreover, all of Si, Fe, Cr, Zn and Ti are present in the core of these embodiments.

- Similarly, Figure 1 discloses a core and a filler material on only one side. Moreover, Figure 1 refers to the specific compositions of the core and the filler material of the examples.

However, claim 1 has not been limited accordingly and, should the specific embodiments or the figure be considered as basis, the amendments would be an intermediate generalisation.

2.5 In addition, the respondent is of the opinion that the mechanism explained in paragraph [0032] of the application as originally filed excluded an intermediate layer, as confirmed by paragraphs [0033] and [0034] of the application as originally filed, stating that the core was clad with a filler material.

However, this argument is not convincing. According to paragraph [0032], Mg is initially present in a limited amount in the core. During heating, it diffuses from the core to the filler.

This mechanism does not exclude intermediate layers per se. Depending on the composition, numerous types of intermediate layers are imaginable that allow for Mg diffusion, depending on the composition, the structure and the thickness of the intermediate layer.

Paragraphs [0033] and [0034] can also not be relied on, in particular since paragraph [0034] discloses a closed core composition ("core having a chemical composition that consists of ..."; emphasis added by the board) that does not comprise Mn or Cu, contrary to claim 1 of the main request. Hence, this paragraph is not directed to the invention of claim 1 in a direct and unambiguous manner.

Similarly, the fact that the core is clad with the filler (paragraph [0034]) does not necessarily mean that the core is directly clad, i.e. without an intermediate layer.

2.6 The respondent further argues that the application as originally filed did not disclose further layers. A sacrificial layer, for example, had nothing to do with the invention, which was about the role of Mg diffusion. The same held for an additional layer on the second side (if the filler material was only clad to the first side of the core material).

However, in the present case, the mere fact that further layers (such as an intermediate layer like that of D8/D8WO) are not explicitly disclosed in the application as originally filed does not mean that the absence of further layers is directly and unambiguously disclosed.

The presence of such additional layers is also not hypothetical, contrary to the respondent's opinion. Thus,

- D8/D8WO discloses an "interlayer" between the core and the filler material (claim 1), and

- it has not been disputed that the application of a sacrificial (anode) layer is frequent in this field. Even if it were acknowledged that the skilled person would not contemplate such a layer on the side with the filler material (since it would have to be removed prior to brazing), they could well contemplate such a layer on the second side of the core.

2.7 In the present case, the replacement of "having" by "consisting of" therefore creates a criticality as to the presence of only the core and the filler material clad to one or both sides of the core which is not present as a sub-combination in the application as originally filed.

Consequently, the main request does not fulfil the requirements of Article 123(2) EPC.

Auxiliary requests

3. Article 123(2) EPC

Since claim 1 of auxiliary requests I and II also requires that the brazing sheet consists of a core and a filler material clad to one or both sides of the core, these requests fail for the same reason as the main request (Article 123(2) EPC).