DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1-3, 6-7, 14 and 16-17 are rejected under 35 U.S.C. 103 as being unpatentable over Kitajima et al. (US 6184475, hereafter “Kitajima”) in view of Applicant-admitted prior art (AAPA, see specification) & Yoshikawa et al. (US 10213879, “Yoshikawa”).
Regarding claim 1, Kitajima discloses a method of soldering of printed circuit boards using a solder bath of solder alloy (fig. 27- step 14, col. 18, lines 45-52), the method comprising initially introducing a Bi-containing solder alloy (col. 2, lines 15-38; claims 1-2) to the solder bath. Kitajima teaches that solder alloy melting temperature increases with increasing Bi content and therefore, Bi content is adjusted to control the melting temperature of the solder (figs. 1-2; col. 10, lines 26-29) - exemplary solder alloys includes approximately 46-55 wt% Bi (claims 1-2). Kitajima further teaches that satisfactory properties of tensile strength and elongation are obtained when the Bi content exceeds about 5 wt% but smaller than 60 wt% (col. 10, lines 15-51). In this manner, Kitajima teaches adjusting the Bi content in the solder alloy.
Kitajima does not disclose replenishing the solder bath with additional solder (Sn or Sn-Bi alloy). However, the concept of refilling/replenishing the solder bath is known in the art. Applicant’s original specification admits (AAPA) that a technique of replenishing solder bath to maintain solder alloy composition has been known in the prior art (JP 3312618) (see Background- [0007])- in this case, solder alloy with certain Cu content is additionally supplied to the solder bath so that the molten solder in the bath can be returned to a predetermined Cu content [0007]. Similarly, Yoshikawa discloses a solder supplying method comprising initially introducing a Bi-containing solder alloy (see table 1 solder alloy examples) to a solder bath (col. 8, lines 38-45; col. 9, lines 10-12), and then replenishing with solder alloy to maintain a desired composition when the bath composition changes due to usage (col. 8, lines 40-50) – the replenishing step meets supplying an additionally supplied solder including Sn-Ag-Bi solder alloy (claims 1-2). Yoshikawa teaches a low-Bi solder alloy with Bi content in a range of 0.1-0.8% for enhancing thermal fatigue resistance (col. 5, lines 20-29), which is lower than initial Bi content (46-55 wt%) in the solder alloy of Kitajima. Accordingly, the Bi content in the solder is an adjustable variable for achieving art-recognized results of melting temperature, desired mechanical properties such as tensile strength & elongation (as taught by Kitajima) and thermal fatigue resistance (as taught by Yoshikawa), and thus is a result-effective variable.
Given teachings of Kitajima, AAPA & Yoshikawa, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to replenish the solder bath with a Bi-solder alloy to adjust the Bi content of the Bi-containing solder alloy (46-55% Bi) in the method of Kitajima through process optimization, since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art. MPEP 2144.05 (II). Hence, Kitajima as modified in light of AAPA & Yoshikawa discloses initially introducing a Bi-containing solder alloy (46-55 wt% Bi) to a solder bath and then replenishing with a lower Bi (e.g. 0.1-0.8 wt%) Sn-Ag-Bi solder alloy, thereby adjusting the Bi content in the solder bath so as to maintain desired bath composition with a motivation of obtaining target mechanical properties such as tensile strength, elongation and fatigue resistance in the soldered joints of printed circuit boards.
As to claim 2, Kitajima discloses that the Bi-containing solder alloy contains at least indium In (figs. 1-2). Yoshikawa discloses that Bi-containing solder alloy and the additionally supplied solder each contain at least one of Ag, In and Zn (fig. 3; col. 11, lines 6-32).
As to claims 3 and 14, Kitajima discloses that the Bi-containing solder alloy is an Sn-Bi solder alloy (figs. 1-2). Yoshikawa also discloses Sn-Bi-Ag solder alloy (fig. 3; col. 11, lines 6-32).
As to claims 6-7 and 16-17, Kitajima as modified by Yoshikawa above encompasses supplying additional solder adjusting the Bi content in the solder bath to maintain desired content with a motivation of obtaining target mechanical properties such as tensile strength, elongation and fatigue resistance in the soldered joints of the circuit boards/substrates. Accordingly, it would have been obvious to one of ordinary skill in the art to supply the additional solder based on a Bi content in the solder bath at given time in the soldering method of Kitajima in order to ensure that desired and consistent amount or concentration of solder alloy is maintained through the flow soldering process of large number of circuit boards/substrates.
Claims 4-5, 8-13, 15 and 18-19 are rejected under 35 U.S.C. 103 as being unpatentable over Kitajima, AAPA & Yoshikawa as applied to claim 1-3 above, and further in view of Ojima et al. (US 7628308, hereafter “Ojima”).
As to claims 4-5, 10-13, 15 and 19, examiner first notes that any interval or timing meets broad feature of “predetermined” intervals or timing. Yoshikawa teaches replenishing solder to the solder bath during flow soldering (col. 8, lines 40-48), but appears to be silent with respect to the replenishing solder being same as the initial composition or supplying amount. Nonetheless, such options concerning replenishing solder are within common knowledge of ordinary artisan and known in the art. Ojima is directed to method of replenishing a solder bath during soldering so as to maintain the surface level of molten solder in the bath (abstract). Ojima teaches that during flow soldering, solder consumed includes portions adhered to the printed circuit boards and a portion discharged to the exterior of the bath/tank as dross, and consequently, additional solder alloy in an amount substantially equal to the lost amount of these portions is supplied to the solder bath (col. 3, lines 21-26); a replenishment solder alloys having the same composition as the initial composition of the solder alloy is supplied so that fluctuations in the solder bath composition can be minimized (col. 3, lines 50-56). Ojima further teaches that the replenishment solder alloy is charged in the same or greater proportion than the rate of the decrease in consumed solder in the bath as soldering progresses, thereby controlling the concentration of oxidation suppressing element within a prescribed range and reducing dross (col. 4, lines 1-37). Accordingly, one of ordinary skill in the art would have found it obvious to supply additional amounts of Bi-containing solder being same as the initial composition and supply replenishing solder alloy in amount equal to consumed solder alloy in the solder bath in the method of Kitajima, AAPA & Yoshikawa with motivation(s) to maintain the surface level of molten solder and minimize fluctuations in the solder bath composition, as suggested by Ojima.
As to claims 8-9 and 18, Kitajima as modified by Yoshikawa above encompasses supplying additional solder adjusting the Bi content in the solder bath to maintain desired content with a motivation of obtaining target mechanical properties such as tensile strength, elongation and fatigue resistance in the soldered joints of the circuit boards/substrates. Accordingly, it would have been obvious to one of ordinary skill in the art to supply the additional solder based on a Bi content in the solder bath at given time in the soldering method of Kitajima in order to ensure that desired and consistent amount or concentration of solder alloy is maintained through the flow soldering process of large number of circuit boards/substrates.
Response to Amendment and Arguments
Applicant's amendment and arguments filed 8/5/26 have been fully considered. The amendment(s) overcomes 112 indefinite rejections from previous office action. New ground(s) of prior art rejection based on new reference of Ojima has been set forth above in light of amended claims 4-5 and 8-19 and thus, Applicant’s arguments concerning these amended claims are moot.
Regarding claim 1, Applicant argues that Bi is rarely used in electrode plating and not typically used in substrates so as to leach into the solder bath. A skilled person familiar with the cited art would assume that the Bi content in the solder bath remains constant.
In response, examiner respectfully disagrees with notion that Bi remains constant in the solder bath. In fact, it is common knowledge to skilled artisan that solder bath composition changes (even if slightly) during flow soldering, and this is evidenced by teachings of Yoshikawa (col. 8, lines 40-50). Applicant’s above argument concerning Bi’s absence in electrode plating or leaching into the solder bath appears to be misguided and not relevant since the rejection never stated that Bi is used in the substrate or leaches into the solder bath. This line of argument is not persuasive.
Applicant further argues that if Bi were consumed in the solder bath containing an Sn-Ag-Bi solder alloy, a person of skill in the art will focus on the Bi content and therefore, introduce a solder alloy with the same composition as the one in the solder bath, or a solder alloy with a higher Bi content. This differs significantly from claimed invention introducing a low-Bi solder alloy which contains a lower Bi than the solder alloy in the solder bath.
In response, examiner submits that adjustment of Bi content in solder alloy of the solder bath is art-recognized result-effective variable as explained in the combination of Kitajima, AAPA & Yoshikawa, which encompasses introducing solder alloy having any Bi content, including lower, higher or same as that of the initial Bi-containing solder. One of ordinary skill would be motivated to adjust the Bi content in the solder bath with replenishing solder alloy in order to maintain desired solder bath composition and achieve targeted mechanical properties such as tensile strength, elongation and fatigue resistance in the soldered joints. Examiner points out that amended claim 4 in fact recites introducing a solder alloy with the same composition as the initial Bi-containing solder and so this approach seems conventional to one of ordinary skill in the art, as recognized in the argument above. Attention is also drawn to newly cited reference of Ojima, which teaches supplying replenishment solder alloy(s), including same composition as the initial composition of the solder alloy, to the solder bath so that fluctuations in the solder bath composition can be minimized.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Inquiry
Any inquiry concerning this communication or earlier communications from the examiner should be directed to DEVANG R PATEL whose telephone number is (571) 270-3636. The examiner can normally be reached on Monday-Friday 8am-5pm, EST.
To schedule an interview, Applicant is encouraged to use the USPTO Automated Interview Request (AIR) at https://www.uspto.gov/patents/laws/interview-practice. Communications via Internet email are at the discretion of Applicant. If Applicant wishes to communicate via email, a written authorization form must be filed by Applicant: Form PTO/SB/439, available at www.uspto.gov/patent/patents-forms. The form may be filed via the Patent Center and can be found using the document description Internet Communications, see https://www.uspto.gov/patents/apply/forms. In limited circumstances, the Applicant may make an oral authorization for Internet communication. See MPEP § 502.03.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Keith Walker can be reached on 571-272-3458. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
Information regarding the status of an application may be obtained from the Patent Center. For more information, see https://patentcenter.uspto.gov. For questions, technical issues or troubleshooting, please contact the Patent Electronic Business Center at ebc@uspto.gov or 1-866-217-9197 (toll-free).
/DEVANG R PATEL/
Primary Examiner, AU 1735
Prosecution Insights