Monday, 5 January 2015

T 1827/12 - Unavoidable impurities



This opposition appeal considered the question whether an amendment extended the scope of protection. Claim 1 of the sole request contained the following features. The amendments are shown with respect to the claim as granted:



A glass article with a metal member joined thereto,
(...)
(c) wherein the two joining planes of the metal member are fixed (...) with a lead-free solder alloy containing Sn as a main component, and
(...)
(e) characterized in that the lead-free solder alloy is an Sn-Ag based alloy that contains 2 to 4 mass% Ag, and a content of other minor components except for Sn and Ag in the Sn-Ag based alloy is 0.5 mass% or lessin which the rest is Sn, and


The opponent objected (amongst other objections) that this amendment broadened the claim after grant. The board did not agree.


Summary of Facts and Submissions
(...)
The patent had been amended in such a way as to extend the protection it conferred (Article 123(3) EPC). Substituting in feature (e) the term "a content of other minor components except for Sn and Ag in the Sn-Ag based alloy is 0.5 mass% or less" from claim 1 as granted for "in which the rest is Sn" extended the scope of the patent as granted. The former term limited the amount of other minor components, such as impurities, in the alloy to up to 0.5 mass%, whereas according to the new wording the amount of impurities could reach higher levels beyond 0.5 mass%. Deletion of the former term therefore broadened claim 1. The patent as granted did not specify what was to be understood by 'other minor components'. These additional minor components had to be interpreted in the patent as granted as any 'other element' within the alloy and included also impurities. It was further common practice for the skilled person that elements in the alloy composition which did not add up together to 0.5 mass% of the alloy were not specified in the composition but just generally referred to as other components. The skilled person knew that impurities had a significant effect on the properties of a metal alloy (see T 184/05), and their concentration level could not be regarded in isolation from the specific examples.
(...)
Reasons for the Decision
2. Extension of scope of protection - Article 123(3) EPC

2.1 The amended European patent according to the sole request does not extend the protection conferred within the meaning of Article 123(3) EPC.

2.2 In its granted version, claim 1 determines the composition of the lead-free solder alloy as including a content of other minor components except for Sn and Ag of 0.5 mass% or less. According to the documents of the present request, the above-mentioned feature of granted claim 1 is replaced by "in which the rest is Sn", and the last two sentences from paragraph [0020] of the description of the granted patent have been deleted, namely: "The Sn-Ag alloy may contain other minor components. In this case it is preferable that the content of the minor components is 0.5 mass% or less".

2.3 Any reference to other minor components has thus been deleted in the description. As agreed by both parties, when explicitly claiming "other minor components" the claimed solder alloy includes any kind of voluntarily added elements as well as unavoidable ones such as impurities, in particular because this term is not further specified in the patent as granted (see paragraph [0020] of the description). Moreover, in the Board's judgment, the sentence in paragraph [0020] that the "Sn-Ag alloy may contain other minor components", i.e. that minor components can be added on purpose or be excluded, would be contradictory if "other minor components" were equated with "impurities", which by nature are unavoidable. By deleting the references to other minor components in paragraph [0020] of the description, which clearly indicated that they were optional components, and by the amendment to claim 1 as granted according to the sole request, the composition of the claimed solder alloy has been restricted to silver, tin and an unavoidable amount of impurities, since it is well known to the skilled person that a solder alloy will never be pure and thus contains unavoidable impurities.

Therefore, with respect to the composition of the alloy solder as granted, the scope of protection of the amended patent according to the sole request has been limited to a lead-free Sn-Ag based solder alloy that contains 2 to 4 mass% of Ag, in which the rest is Sn, further, implicitly, containing an unavoidable amount of impurities.

2.4 In accordance with the respondent's opinion, the range of "0.5 mass% or less" claimed in the granted version for the other minor components included as a lower limit "0.0 mass%" of other minor components. The present request is limited, due to the deletion of other minor components in claim 1 and the definition that "the rest is Sn", to this lower limit, i.e. in this respect the scope of protection has only been restricted compared to the patent as granted.

2.5 It remains to be discussed whether, based on claim 1 and the description of the sole request, the content of unavoidable impurities might include an amount greater than 0.5 mass% of the solder alloy, as alleged by the appellant. Starting from the undisputed understanding of the term "other minor components" in granted claim 1, comprising voluntarily added elements as well as unavoidable impurities, their total content was explicitly restricted to "0.5 mass% or less" in the granted version. In fact, this restriction was deleted in claim 1 according to the sole request. However, as a further limitation claim 1 according to the sole request now specifies a composition "in which the rest is Sn". In the absence of any evidence that a content of impurities in the solder alloy could amount to more than 0.5 mass% without being explicitly mentioned, the Board finds that, on a reasonable interpretation of the subject-matter of claim 1 according to the present sole request, such content of unvoidable impurities higher than 0.5 mass% must be ruled out. A person skilled in the art describing the content of solder alloys would specify an element of which the content is greater than 0.5 mass% of the alloy because it will affect the properties of the alloy. In the Board's judgement, this also applies to a group of elements in the alloy, such as impurities, if their content exceeds 0.5 mass% because such impurity content would have a considerable influence on the properties of a metal alloy, as stated by the appellant himself.

In this context, the appellant cites decision T 184/05, which again refers to decision T 201/83 (OJ EPO 1984, 481) stating (point 12 of the Reasons, last sentence) that "an amendment of a concentration range in a claim for a mixture, such as an alloy, is allowable on the basis of a particular value described in a specific example, provided the skilled man could have readily recognised this value as not so closely associated with the other features of the example as to determine the effect of that embodiment of the invention as a whole in a unique manner and to a significant degree". However, the present application and the specific examples described therein are totally silent with regard to impurities and their concentration range, and only in the general part of the description, as originally filed, is it mentioned that other minor components may - optionally - be included up to a maximum content. Therefore, the the Board finds that the case law referred to by the appellant - which relates to the extraction of a particular value of a concentration range of an alloy from a given example comprising further features - is considered not to be applicable in the present case, which only excludes an optionally mentioned solder alloy component. In particular, the Board finds that deletion of such optional alloy composition with a limited content of other minor components cannot open the door to an interpretation of the claimed subject-matter which would include an unlimited or unreasonable amount of impurities.

Moreover, as argued by the appellant, it was common practice for the skilled person that elements in the alloy composition which do not add up together to 0.5 mass% of the alloy were not specified but just generally referred to as other components. In the absence of any citation of other minor components in claim 1, reading claim 1 with a mind willing to understand (which comprises the term "in which the rest is Sn"), the skilled reader would at the most assume an insignificant amount - far below 0.5 mass% - of unavoidable components such as unavoidable impurities.

2.6 The Board thus cannot see that the European patent has been amended in such a way as to extend the protection it conferred.

This decision has European Case Law Identifier: ECLI:EP:BA:2014:T182712.20140919. The whole decision can be found here. The file wrapper can be found here. Scan by Jamie obtained via Flickr; Original source The Toronto World, May 17, 1902.

No comments :

Post a Comment

Statcounter