Source: http://patents.com/us-9883586.html
Timestamp: 2019-01-17 01:00:16
Document Index: 342832582

Matched Legal Cases: ['Application No. 14743400', 'Application No. 2014800058161', 'Application No. 2013', 'Application No. 2013', 'Application No. 103102638', 'Application No. 2013']

US Patent # 9,883,586. Wiring substrate for bonding using solder having a low melting point and method for manufacturing same - Patents.com
United States Patent 9,883,586
Tsuchida , et al. January 30, 2018
Wiring substrate for bonding using solder having a low melting point and method for manufacturing same
There is provided a wiring substrate including an electrode including Cu or a Cu alloy, a plating film having a film including at least Pd, formed on the electrode, and a solder which is bonded onto the plating film by heating, has a melting point of lower than 140.degree. C., and includes Pd dissolved therein, a Pd concentrated layer being absent between the solder and the electrode.
Tsuchida; Tetsuyuki (Tokyo, JP), Okubo; Toshikazu (Tokyo, JP), Shohji; Ikuo (Kiryu, JP), Hirata; Akihiro (Kiryu, JP)
Family ID: 1000003092320
14/808,275
US 20150334828 A1 Nov 19, 2015
PCT/JP2014/051581 Jan 24, 2014
Jan 28, 2013 [JP] 2013-013244
Current CPC Class: H05K 1/09 (20130101); B23K 1/0008 (20130101); B23K 1/008 (20130101); B23K 1/0016 (20130101); B23K 1/19 (20130101); B23K 35/262 (20130101); C22C 13/02 (20130101); C25D 7/00 (20130101); H05K 3/10 (20130101); H05K 3/244 (20130101); H05K 2203/043 (20130101); H01L 2924/0002 (20130101); H05K 2201/0341 (20130101); H01L 2924/0002 (20130101); H01L 2924/00 (20130101)
Current International Class: H05K 1/09 (20060101); C22C 13/02 (20060101); H05K 3/24 (20060101); B23K 1/008 (20060101); H05K 3/10 (20060101); B23K 1/19 (20060101); B23K 1/00 (20060101); C25D 7/00 (20060101); B23K 35/26 (20060101)
Field of Search: ;174/257,250,251,255,256,259,261 ;29/825,829,831,846
2013/0077275 March 2013 Kariyazaki
2013/0135834 May 2013 Horikawa
1430465 Dec 2002 CN
1998074 Jul 2007 CN
9-266373 Oct 1997 JP
10-41621 Feb 1998 JP
2001-077290 Mar 2001 JP
2003-174254 Jun 2003 JP
2006-122913 May 2006 JP
2006-339219 Dec 2006 JP
4822526 Nov 2011 JP
200850107 Dec 2008 TW
201107071 Mar 2011 TW
International Search Report dated Mar. 11, 2014 in corresponding international application PCT/JP2014/051581. cited by applicant .
Sandy et al., "Advantages of Bismuth-based Alloys for Low Temperature Pb-Free Soldering and Rework From One Engineer to Another", Indium Corporation Tech Paper, Indium Corporation, Dec. 20, 2012, pp. 1-7. cited by applicant .
Ferrer et al., "57Bi--42Sn--1Ag: A Lead Free, Low Temperature Solder for the Electronic Industry", Hewlett-Packard Company, Sep. 25, 2003, pp. 1-7. cited by applicant .
Romm et al., "Evaluation of Nickel/Palladium-Finished ICs with Lead-Free Solder Alloys", Application Report SZZA024, Texas Instruments, Jan. 2001, pp. 1-17. cited by applicant .
Extended European Search Report dated Aug. 31, 2016 in corresponding European Patent Application No. 14743400.5. cited by applicant .
English translation of Chinese Office Action dated Mar. 13, 2017 in corresponding Chinese Patent Application No. 2014800058161. cited by applicant .
Japanese Office Action dated Dec. 20, 2016 in corresponding Japanese Patent Application No. 2013-013244. cited by applicant .
Translation of Japanese Office Action dated Dec. 20, 2016 in corresponding Japanese Patent Application No. 2013-013244 (Translation of Document AM of the Information Disclosure Statement filed on Mar. 20, 2017). cited by applicant .
Taiwanese Office Action dated Oct. 17, 2017 in corresponding Taiwanese Patent Application No. 103102638. cited by applicant.
This application is a continuation application based on a PCT patent application Ser. No. PCT/JP2014/051581, filed Jan. 24, 2014, whose priority is claimed on Japanese Patent Application No. 2013-013244 filed Jan. 28, 2013, the entire contents of which are hereby incorporated by reference.
1. A method for manufacturing a wiring substrate comprising: forming a plating film comprising a film comprising at least Pd on an electrode comprising Cu or a Cu alloy; forming a solder resist layer protecting a portion of the electrode outside of a bonding site of a solder, the solder resist fully covering all side surfaces of the electrode; and bonding, onto the plating film, the solder having a melting point of lower than 140.degree. C. onto the plating film by heating, to uniformly dissolve the Pd in the solder and remove the Pd from the plating film, the bonding the solder onto the plating film by heating being performed under one of the following predetermined thermal conditions: (1) reflow treatment at a time of bonding the solder is performed one to five times under a condition where a peak temperature is 139.degree. C. or higher and 169.degree. C. or lower, a time of maintaining a temperature at 139.degree. C. or higher and 169.degree. C. or lower is shorter than 90 seconds, and a total time of heating treatment including reflow is 300 seconds or shorter, (2) after bonding the solder, a heating treatment of maintaining the temperature at 139.degree. C. or higher and 169.degree. C. or lower for 90 seconds or longer is performed, and (3) reflow treatment at the time of bonding the solder is performed one to five times under a condition where a peak temperature is 139.degree. C. or higher and 169.degree. C. or lower, a total time of heating treatment including reflow is 300 seconds or shorter, and the time of maintaining the temperature at 139.degree. C. or higher and 169.degree. C. or lower is 90seconds or longer.
2. The method for manufacturing a wiring substrate according to claim 1, wherein when the plating film is formed, a thickness of the film comprising Pd is 0.01 .mu.m or more and 5 .mu.m or less.
In addition, as a solder mounting material, solder including no lead (Pb) has been used instead of conventional Sn--Pb based solder that is subject to RoHS restrictions. Particularly, a Sn--Ag--Cu based solder such as Sn-3Ag-0.5Cu has been widely used. However, the use of a Sn--Ag--Cu based solder entails the following disadvantages such as that when a component with a low heat resistance is mounted, thermal degradation of the component occurs because of an increase in reflow temperature or that when the solder is bonded onto a thin substrate, the substrate becomes bent because of heat. Particularly, for using FC-BGA, reflow should be performed multiple times based on, for example, the number of substrates to be laminated, and these disadvantages further limit a mountable component and the thickness of substrate. In addition, an intermetallic compound layer formed in a bonding interface between a plating film and a solder that are formed on an electrode grows thick because of the rise in reflow temperature, and this results in degradation of impact resistance. Thus, it has been required to lower a mounting temperature.
In order to lower a mounting temperature, solder having a low melting point is used. Such solders may include Sn-58 wt % Bi and Sn-57 wt % Bi-1 wt % Ag solders. Sn-58 wt % Bi and Sn-57 wt % Bi-1 wt % Ag solders have a low melting point of 139.degree. C. and a mounting temperature of approximately 170.degree. C. even at the peak. Thus, using these solders may lower the mounting temperature by approximately 60.degree. C. in comparison with other Sn--Ag--Cu based lead-free solders and by approximately 30.degree. C. in comparison with Sn-37 wt % Pb solder.
Sn-58 wt % Bi and Sn-57 wt % Bi-1 wt % Ag, however, are not widely used because of their hard and brittle properties that degrade impact resistance. However, there is an example of improving the ductility of solder by using Sn-57 wt % Bi-0.5 wt % Sb solder where Sb is added to Sn--Bi.
However, the solder includes 80 wt % to 100 wt % of Bi and has a bonding temperature of 270.degree. C. or higher, and thus it is difficult to be used for components with low heat resistance.
The present invention takes into consideration of the above circumstances and provides a wiring substance capable of achieving highly reliable solder mounting even when a solder having a melting point of lower than 140.degree. C. is used and provides a method for manufacturing the same.
According to a first aspect of the present invention, there is provided a wiring substrate including an electrode including Cu or a Cu alloy, a plating film formed on the electrode and including a film including at least Pd, and a solder bonded onto the plating film by heating, having a melting point of lower than 140.degree. C., and including Pd dissolved therein, in which a Pd concentration layer is absent between the solder and the electrode.
According to a third aspect of the present invention, a method is provided for manufacturing a wiring substrate including forming a plating film including a film including at least Pd on an electrode including Cu or a Cu alloy, and bonding solder having a melting point lower than 140.degree. C. onto the plating film by heating to dissolve the Pd in the solder.
According to a fourth aspect of the present invention, in the third aspect, the solder is bonded onto the plating film by heating under a predetermined thermal condition that may be one of the following that (1) reflow treatment at the time of bonding the solder is performed under a condition where a peak temperature is 139.degree. C. or higher and the time of maintaining the temperature at 139.degree. C. or higher is less than 90 seconds, and the reflow treatment is performed at least once under the same condition, (2) after bonding the solder, heating treatment of maintaining the temperature at 139.degree. C. or higher for 90 seconds or longer is performed, and (3) the bonding of solder is performed under a condition where reflow treatment performed in which a peak temperature is 139.degree. C. or higher and the time of maintaining the temperature at 139.degree. C. or higher is 90 seconds or longer, is performed at least once.
According to a fifth aspect of the present invention, in the third or fourth aspect, when the plating film is formed, the thickness of the film including Pd may be 0.01 .mu.m or more and 5 .mu.m or less.
According to a wiring substrate and method for manufacturing the same of the present invention, high reliability of solder mounting can be achieved even when a solder having a melting point lower than 140.degree. C. is used.
Also, in the wiring substrate of the present exemplary embodiment, solder (for example, solder layer) including at least Sn and Bi is bonded onto the electrode having the plating film, with a melting point of lower than 140.degree. C. Here, the thickness of the Pd plating film to be stacked and the reflow condition are controlled so as to not form a Pd concentrated layer, which will be described later, between the electrode and the solder, caused by reflow treatment during solder bonding and another heating treatment after thermal bonding by reflow treatment.
Particularly, according to the wiring substrate of the present exemplary embodiment, it is controlled not to form a Pd concentrated layer between the electrode and the solder by any one of the following (1) to (3). (1) Reflow treatment at the time of bonding the solder is performed under a condition where the peak temperature is 139.degree. C. or higher and the time of maintaining the temperature at 139.degree. C. or higher is less than 90 seconds, and the reflow treatment is performed at least once under the same condition. (2) In (1), after bonding the solder, heating treatment of maintaining the temperature at 139.degree. C. or higher for 90 seconds or longer is performed. (3) Reflow treatment at the time of bonding the solder is performed at least once under a condition where a peak temperature is 139.degree. C. or higher and the time of maintaining the temperature at 139.degree. C. or higher is 90 seconds or longer.
The term "Pd concentrated layer" refers to a layer-shaped aggregate of Pd remaining on the interface between a plating film and an intermetallic compound layer formed by solder bonding, because not all Pd is dissolved in a solder when the solder is bonded onto a single layer plating film or a multilayer plating film including a Pd plating film. When a Pd concentrated layer is formed between an electrode and a solder, the Pd concentrated layer may become a cracking point upon impact, and this may degrade reliability of mounting.
The present application provides a thermal condition where the Pd concentrated layer is not formed in a solder bonding process. Particularly, reflow treatment is performed at least once under a condition where a peak temperature is 139.degree. C. or higher and the time of maintaining the temperature at 139.degree. C. or higher is less than 90 seconds. Alternatively. Pd in the plating film is uniformly dissolved in a solder bulk and is removed by heating treatment where the time of maintaining the temperature at 139.degree. C. or higher is 90 seconds or longer, performed after solder bonding. Alternatively, if the reflow treatment during solder bonding is performed under a condition where a peak temperature is 139.degree. C. or higher and the time of maintaining the temperature at 139.degree. C. or higher is 90 seconds or longer, Pd in the plating film may be uniformly dissolved in a solder bulk even by one reflow, so that no Pd concentrated layer may be formed.
The thickness of the Ni plating film 18 is preferably 0.5 .mu.m or greater, more preferably 3 .mu.m to 5 .mu.m.
As long as the thickness of the Ni plating film 18 is the lower limit or greater, the thickness of the plating film 14 to be formed tends to be more uniform. Thereby, the thickness of the intermetallic compound layer 28 that is formed on the bonding interface between the plating film and the solder tends to be more uniform, and impact resistance is improved. Setting the thickness of the Ni plating film to 3 .mu.m to 5 .mu.m may achieve a greater effect. Further, setting the thickness of the Ni plating film 18 to 5 .mu.m or thinner may shorten the plating time.
For the Pd plating film 20, either an electroless plating film or an electrolytic plating film may be used. For an electroless Pd plating film, for example, either a known electroless Pd--P plating film or an electroless pure Pd plating film may be used, and for example, other elements than P may be included therein.
For an electrolytic Pd plating film, any one of a non-bright plating film, a semi-bright plating film, and a bright plating film may be used, and Pd--Ni, Pd--Co, Pd--Cu and Pd--In plating films that are formed with metals different from the eutectoid may be used.
The thickness of the Pd plating film 20 is preferably 0.01 .mu.m or greater and 5 .mu.m or less, more preferably 0.05 .mu.m or greater and 1 .mu.m or less. When the thickness of the Pd plating film is less than 0.01 .mu.m, a Ni/Pd/Au plating film is formed on an electrode including Cu, and by reflow, solder having a melting point lower than 140.degree. C. and configured to include at least Sn and Bi is bonded by heating under a reflow condition such that the temperature of 139.degree. C. or higher lasts shorter than 90 seconds. In this case, when the Pd plating film is completely dissolved in the solder during the heat bonding process, a large amount of Ni under the Pd plating film is brought into dissolution reaction because the Pd plating film is thin. Here, when the Ni plating film is, for example, an electroless Ni plating film constituted with P as eutectoid, a P-rich layer is formed on the bonding interface between the Ni plating film and the solder, and this degrades reliability of mounting. Thus, this case is not preferable.
On the other hand, when the thickness of the Pd plating film 20 is greater than 5 .mu.m, an excessive thermal condition may be required in order to prevent the presence of a Pd concentrated layer.
The thickness of the Au plating film 22 is preferably 0.5 .mu.m or less, more preferably 0.05 .mu.m or less, in order to obtain sufficient solderability. As long as the thickness of the Au plating film 22 is the upper limit or less, segregation of the intermetallic compound on the bonding interface between the plating film 14 and the solder 26 may be readily inhibited, and reliability of solder mounting may be improved.
The solder 26 of the present exemplary embodiment has a melting point of lower than 140.degree. C., and includes at least Sn and Bi. Examples of the solder may include Sn-58 wt % Bi, Sn-57 wt % Bi-1 wt % Ag, Sn-57 wt % Bi-0.5 wt % Sb, and the like.
Thermal condition when the solder 26 is bonded will be described. First, a peak temperature in the reflow condition is maintained to be 139.degree. C. or higher. The time of maintaining the temperature at 139.degree. C. or higher is set to 90 seconds or longer in the case of the thickness of the Pd plating film 18 being 0.1 .mu.m or greater and no Pd concentrated layer is generated between the electrode 12 and the solder 26 in one reflow. In the case that a Pd concentrated layer is removed by heating treatment performed after thermal bonding in one reflow, the time of maintaining the temperature at 139.degree. C. or higher in the reflow is set to shorter than 90 seconds.
When the thickness of the Pd plating film 18 is less than 0.1 .mu.m, it is possible to prevent a Pd concentrated layer from being generated even in one reflow where the time of maintaining the temperature at 139.degree. C. or higher is shorter than 90 seconds.
For example, when the solder 26 is bonded onto a Ni/Pd/Au plating film or a Ni/Pd plating film by heating, an intermetallic compound layer such as (Cu, Ni).sub.3Sn.sub.4 and Ni.sub.3Sn.sub.4 is formed between the electrode and the solder. When the solder 26 is bonded onto a Pd/Au plating film or a Pd plating film by heating, an intermetallic compound layer consisting of Cu.sub.6Sn.sub.5 and Cu.sub.3Sn is formed on the electrode and the solder.
Pd and Au are dissolved in the solder 26 when the solder 26 is bonded by heating. The Pd plating film 20 has a slower dissolving rate than the Au plating film 22 in the solder. Thus, for example, when the solder is bonded onto the Pd plating film 20 having the thickness of 0.1 .mu.m in one reflow performed under a reflow condition where a peak temperature is 139.degree. C. or higher, and the time of maintaining the temperature at 139.degree. C. or higher is shorter than 90 seconds, a Pd concentrated layer is formed on the bonding interface between the plating film 14 and the solder 26, and thus reliability of solder mounting deteriorates. However, when the solder is bonded in one reflow performed under a reflow condition where a peak temperature is 139.degree. C. or higher, and the time of maintaining the temperature at 139.degree. C. or higher is 90 seconds or longer, no Pd concentrated layer is formed between the electrode 12 and the solder 26, and thus reliability of solder mounting improves.
However, when the solder is bonded in one reflow under a reflow condition where a peak temperature is 139.degree. C. or higher, and the time of maintaining the temperature at 139.degree. C. or higher is shorter than 90 seconds, a Pd concentrated layer may be formed between the electrode 12 and the solder 26. In such a case, Pd may be completely dissolved in the solder 26 to remove the Pd layer, by performing repeated reflow or performing heating treatment after bonding at a temperature at 139.degree. C. or higher for 90 seconds or longer. Then, an intermetallic compound layer is uniformly formed on the bonding interface between the plating film 14 and the solder 26, which allows stable bonding, and this improves reliability of solder mounting.
In the process of solder bonding, a solder including at least Sn and Bi, with a melting point of lower than 140.degree. C., described above, is bonded onto the plating film that is on the electrode 12.
Example 1: A flux is applied on the plating film 14 that is formed on the electrode 12, a solder ball constituted with the solder 26 is mounted thereon, and the thermal bonding is performed under a reflow condition where a peak temperature is 139.degree. C. or higher, and the time of maintaining the temperature at 139.degree. C. or higher is shorter than 90 seconds.
Example 2: A solder paste of the solder 26 is printed on the plating film 14, and the thermal bonding is performed under the above-described reflow condition.
In another aspect, only one reflow may be performed under a condition where a peak temperature is 139.degree. C. or higher, and the time of maintaining the temperature at 139.degree. C. or higher is 90 seconds or longer, instead of the above-described reflow condition. By doing this, Pd is completely dissolved in a solder bulk, and thus no Pd concentrated layer is generated.
In yet another aspect, after the solder 26 is bonded, the Pd concentrated layer may be removed by performing heating treatment where the time of maintaining the temperature at 139.degree. C. or higher is 90 seconds or longer.
Electrolytic Cu plating was performed on a copper coated laminate that is made of a glass epoxy resin, having the thickness of 0.8 mm, and the portion out of a pad (having a diameter of 300 .mu.m) is coated with a solder resist (product name: AUS308, manufactured by TAIYO INK MFG. CO., LTD.), to obtain a basic substrate having an electrode 12 consisting of Cu.
The Ni plating film 18 having the thickness of 3 .mu.m was formed on the electrode 12 of the above-mentioned basic substrate, using an electroless Ni plating bath (bath temperature: 81.degree. C.) in which sulfuric acid Ni (20 g/L), sodium hypophosphite (20 g/L) as a reducing agent, lactic acid (30 g/L) as a complexing agent, lead nitrate as a lead salt, and thiourea as a sulfur-based compound were dissolved in water.
Then, the Pd plating film 20 having the thickness of 0.1 .mu.m was formed on the Ni plating film 18, using an electroless Pd plating bath (bath temperature: 43.degree. C.) including Tetraammine Pd (0.8 g/L as Pd), sodium hypophosphite (10 g/L), bismuth nitrate (2 mg/L), and phosphoric acid (10 g/L).
Thereafter, the Au plating film 22 having the thickness of 0.05 .mu.m was formed on the Pd plating film 20, using an electroless Au plating bath (bath temperature: 86.degree. C.) including potassium Au cyanide (1.0 g/L as Au), thiosulfuric acid (1 mg/L), citric acid (25 g/L), and phosphoric acid (10 g/L). Thereby, the plating film 14 in which the electroless Ni plating film/electroless Pd plating film/electroless Au plating film were layered was formed on the electrode 12.
The lead-free Ni plating film 18 having the thickness of 3 .mu.m was formed on the electrode 12 of the basic substrate, using an electroless Ni plating bath (bath temperature: 81.degree. C.) in which sulfuric acid Ni (20 g/L), sodium hypophosphite (20 g/L) as a reducing agent, lactic acid (30 g/L) as a complexing agent, bismuth nitrate as a bismuth salt, and thiourea as a sulfur-based compound were dissolved in water.
Thereafter, the Au plating film 22 having the thickness of 0.05 .mu.m was formed on the Pd plating film 20, using an electroless Au plating bath (bath temperature: 86.degree. C.) including potassium Au cyanide (1.0 g/L as Au), thiosulfuric acid (I mg/L), citric acid (25 g/L), and phosphoric acid (10 g/L). Thereby, the plating film 14 in which the lead-free electroless Ni plating film/electroless Pd plating film/electroless Au plating film were layered was formed on the electrode 12.
The lead-free Ni plating film having the thickness of 3 .mu.m was formed on the electrode 12 of the basic substrate, using an electroless Ni plating bath (bath temperature: 81.degree. C.) in which sulfuric acid Ni (20 g/L), sodium hypophosphite (20 g/L) as a reducing agent, lactic acid (30 g/L) as a complexing agent, bismuth nitrate as a bismuth salt, and thiourea as a sulfur-based compound were dissolved in water.
Thereafter, the Au plating film having the thickness of 0.05 .mu.m was formed on the Ni plating film, using an electroless Au plating bath (bath temperature: 86.degree. C.) including potassium Au cyanide (1.0 g/L as Au), thiosulfuric acid (1 mg/L), citric acid (25 g/L), and phosphoric acid (10 g/L). Thereby, the plating film in which the lead-free electroless Ni plating film/electroless Au plating film were layered was formed on the electrode 12.
The Pd plating film 20 having the thickness of 2.7 .mu.m was formed on the electrode 12 of the basic substrate, using an electroless Pd plating bath (bath temperature: 43.degree. C.) including Tetraammine Pd (0.8 g/L as Pd), sodium hypophosphite (10 g/L), bismuth nitrate (2 mg/L), and phosphoric acid (10 g/L).
Thereafter, the Au plating film 22 having the thickness of 0.06 .mu.m was formed on the Pd plating film 20, using an electroless Au plating bath (bath temperature: 86.degree. C.) including potassium Au cyanide (1.0 g/L as Au), thiosulfuric acid (1 mg/L), citric acid (25 g/L), and phosphoric acid (10 g/L). Thereby, the plating film 14 in which the electroless Pd plating film/electroless Au plating film were layered was formed on the electrode 12.
The Pd plating film having the thickness of 2.7 .mu.m was formed on the electrode 12 of the basic substrate, using an electroless Pd plating bath (bath temperature: 43.degree. C.) including Tetraammine Pd (0.8 g/L as Pd), sodium hypophosphite (10 g/L), bismuth nitrate (2 mg/L), and phosphoric acid (10 g/L). Thereby, the plating film 14 with the single-layer electroless Pd plating film was formed on the electrode 12.
The plating film 14 of a multilayer structure was formed on the electrode 12 of the basic substrate such that the thickness of the Ni plating film 18 is 4.4 .mu.m, the thickness of the Pd plating film 20 is 0.33 .mu.m, and the thickness of the Au plating film 22 is 0.07 .mu.m, using a Ni sulfamate plating bath (bath temperature: 50.degree. C.) including Ni sulfamate (600 g/L), Ni chloride (5 g/L), and boric acid (40 g/L), a commercialized Pd plating bath (bath temperature: 25.degree. C.), and a bright Au plating bath (bath temperature: 60.degree. C.) including cyanide Au potassium (10 g/L), potassium monohydrogen phosphate (45 g/L), and a chelating agent (45 g/L).
A solder ball made of Sn-58 wt % Bi, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the above-described pre-substrate 1, and reflow was preformed five times under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Example 1 was obtained. 10 specimens of Example 1 were manufactured.
A solder ball made of Sn-58 wt % Bi, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 1, and reflow was preformed once under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Comparative Example 1 was obtained. Ten specimens of Comparative Example 1 were manufactured.
A solder ball made of Sn-57 wt % Bi-0.5 wt % Sb, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 1, and reflow was preformed five times under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Example 2 was obtained. Ten specimens of Example 2 were manufactured.
A solder ball made of Sn-57 wt % Bi-0.5 wt % Sb, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 1, and reflow was preformed once under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Comparative Example 2 was obtained. 10 specimens of Comparative Example 2 were manufactured.
A solder ball made of Sn-58 wt % Bi, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 2, and reflow was preformed five times under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Example 3 was obtained. Ten specimens of Example 3 were manufactured.
A solder ball made of Sn-58 wt % Bi, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 2, and reflow was preformed once under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Comparative Example 3 was obtained. Ten specimens of Comparative Example 3 were manufactured.
A solder ball made of Sn-57 wt % Bi-0.5 wt % Sb, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 2, and reflow was preformed five times under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Example 4 was obtained. Ten specimens of Example 4 were manufactured.
A solder ball made of Sn-57 wt % Bi-0.5 wt % Sb, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 2, and reflow was preformed once under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Comparative Example 4 was obtained. Ten specimens of Comparative Example 4 were manufactured.
A solder ball made of Sn-58 wt % Bi, with a diameter of 350 .mu.m, was mounted on the plating film of the pre-substrate 3, and reflow was preformed five times under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Comparative Example 4-1 was obtained. Ten specimens of Comparative Example 4-1 were manufactured.
A solder ball made of Sn-58 wt % Bi, with a diameter of 350 .mu.m, was mounted on the plating film of the pre-substrate 3, and reflow was preformed once under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Comparative Example 4-2 was obtained. Ten specimens of Comparative Example 4-2 were manufactured.
A solder ball made of Sn-57 wt % Bi-0.5 wt % Sb, with a diameter of 350 .mu.m, was mounted on the plating film of the pre-substrate 3, and reflow was preformed five times under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Comparative Example 4-3 was obtained. Ten specimens of Comparative Example 4-3 were manufactured.
A solder ball made of Sn-57 wt % Bi-0.5 wt % Sb, with a diameter of 350 .mu.m, was mounted on the plating film of the pre-substrate 3, and reflow was preformed once under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Comparative Example 4-4 was obtained. Ten specimens of Comparative Example 4-4 were manufactured.
A solder ball made of Sn-58 wt % Bi, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 4, and reflow was preformed five times under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Example 5 was obtained. Ten specimens of Example 5 were manufactured.
A solder ball made of Sn-58 wt % Bi, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 4, and reflow was preformed once under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Comparative Example 5 was obtained. Ten specimens of Comparative Example 5 were manufactured.
A solder ball made of Sn-57 wt % Bi-0.5 wt % Sb, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 4, and reflow was preformed five times under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Example 6 was obtained. Ten specimens of Example 6 were manufactured.
A solder ball made of Sn-57 wt % Bi-0.5 wt % Sb, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 4, and reflow was preformed once under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Comparative Example 6 was obtained. Ten specimens of Comparative Example 6 were manufactured.
A solder ball made of Sn-58 wt % Bi, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 5, and reflow was preformed five times under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Example 7 was obtained. Ten specimens of Example 7 were manufactured.
A solder ball made of Sn-58 wt % Bi, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 5, and reflow was preformed once under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Comparative Example 7 was obtained. Ten specimens of Comparative Example 7 were manufactured.
A solder ball made of Sn-57 wt % Bi-0.5 wt % Sb, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 5, and reflow was preformed five times under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Example 8 was obtained. Ten specimens of Example 8 were manufactured.
A solder ball made of Sn-57 wt % Bi-0.5 wt % Sb, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 5, and reflow was preformed once under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Comparative Example 8 was obtained. Ten specimens of Comparative Example 8 were manufactured.
A solder ball made of Sn-58 wt % Bi, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 6, and reflow was preformed five times under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Example 9 was obtained. Ten specimens of Example 9 were manufactured.
A solder ball made of Sn-58 wt % Bi, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 6, and reflow was preformed once under a condition where the peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Comparative Example 9 was obtained. Ten specimens of Comparative Example 9 were manufactured.
A solder ball made of Sn-57 wt % Bi-0.5 wt % Sb, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 6, and reflow was preformed five times under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Example 10 was obtained. 10 specimens of Example Ten were manufactured.
A solder ball made of Sn-57 wt % Bi-0.5 wt % Sb, with a diameter of 350 m, was mounted on the plating film 14 of the pre-substrate 6, and reflow was preformed once under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 60 seconds. Thereby, a wiring substrate of Comparative Example 10 was obtained. Ten specimens of Comparative Example 10 were manufactured.
A solder ball made of Sn-58 wt % Bi, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 1, and reflow was preformed once under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 90 seconds. Thereby, a wiring substrate of Example 11 was obtained. Ten specimens of Example 11 were manufactured.
A solder ball made of Sn-57 wt % Bi-0.5 wt % Sb, with a diameter of 350 .mu.m, was mounted on the plating film 14 of the pre-substrate 1, and reflow was preformed once under a condition where a peak temperature was 169.degree. C. and the time of maintaining the temperature at 139.degree. C. or higher was 90 seconds. Thereby, a wiring substrate of Example 12 was obtained. Ten specimens of Example 12 were manufactured.
TABLE-US-00001 TABLE 1 Evaluation results of reliability Specimen of solder mounting Time of Rate of each failure mode (%) Type of Number maintaining Solder + Bonding plating of 139.degree. C. or Solder IMC IMC strength film Type of solder reflow higher (s) failure failure failure (N) Example 1 Electroless Sn--58wt%Bi 5 300 40 60 0 4.854 Ni/Pd/Au Comparative Electroless Sn--58wt%Bi 1 60 0 70 30 4.627 Example 1 Ni/Pd/Au Example 2 Electroless Sn--57wt%Bi--0.5wt%Sb 5 300 80 20 0 4.826 Ni/Pd/Au Comparative Electroless Sn--57wt%Bi--0.5wt%Sb 1 60 10 80 10 4.464 Example 2 Ni/Pd/Au Example 3 Lead-free Sn--58wt%Bi 5 300 70 30 0 5.117 electroless Ni/Pd/Au Comparative Lead-free Sn--58wt%Bi 1 60 0 80 20 4.310 Example 3 electroless Ni/Pd/Au Example 4 Lead-free Sn--57wt%Bi--0.5wt%Sb 5 300 70 30 0 4.846 electroless Ni/Pd/Au Comparative Lead-free Sn--57wt%Bi--0.5wt%Sb 1 60 50 50 0 4.802 Example 4 electroless Ni/Pd/Au Comparative Lead-free Sn--58wt%Bi 5 300 20 80 0 4.961 Example 4-1 electroless Ni/Au Comparative Lead-free Sn--58wt%Bi 1 60 70 30 0 5.116 Example 4-2 electroless Ni/Au Comparative Lead-free Sn--57wt%Bi--0.5wt%Sb 5 300 30 70 0 4.888 Example 4-3 electroless Ni/Au Comparative Lead-free Sn--57wt%Bi--0.5wt%Sb 1 60 60 40 0 5.059 Example 4-4 electroless Ni/Au
TABLE-US-00002 TABLE 2 Evaluation results of Specimen reliability of solder Number Time of maintaining mounting Type of plating film Type of solder of reflow 139.degree. C. or higher (s) Bonding strength (N) Example 5 Electroless Pd/Au Sn--58 wt % Bi 5 300 5.410 Comparative Electroless Pd/Au Sn--58 wt % Bi 1 60 3.570 Example 5 Example 6 Electroless Pd/Au Sn--57 wt % Bi--0.5 wt % Sb 5 300 4.902 Comparative Electroless Pd/Au Sn--57 wt % Bi--0.5 wt % Sb 1 60 3.374 Example 6 Example 7 Electroless Pd Sn--58 wt % Bi 5 300 4.681 Comparative Electroless Pd Sn--58 wt % Bi 1 60 4.272 Example 7 Example 8 Electroless Pd Sn--57 wt % Bi--0.5 wt % Sb 5 300 4.969 Comparative Electroless Pd Sn--57 wt % Bi--0.5 wt % Sb 1 60 4.275 Example 8 Example 9 Electrolytic Sn--58 wt % Bi 5 300 5.270 Ni/Pd/Au Comparative Electrolytic Sn--58 wt % Bi 1 60 4.712 Example 9 Ni/Pd/Au Example 10 Electrolytic Sn--57 wt % Bi--0.5 wt % Sb 5 300 4.983 Ni/Pd/Au Comparative Electrolytic Sn--57 wt % Bi--0.5 wt % Sb 1 60 4.414 Example 10 Ni/Pd/Au Example 11 Electroless Ni/Pd/Au Sn--58 wt % Bi 1 90 5.599 Example 12 Electroless Ni/Pd/Au Sn--57 wt % Bi--0.5 wt % Sb 1 90 5.522
As seen from Table 2, when using the plating film of multilayer structure consisting of electroless Pd/Au plating, the plating film of single layer consisting of electroless Pd plating, and the plating film of multilayer structure consisting of electrolytic Ni/Pd/Au, the specimens after 5 times reflow have higher solder bonding, and exhibit higher reliability of solder mounting compared with Comparative Examples corresponding to the each Example. Also, as shown in Examples 11 to 12, in the case where the time of maintaining the temperature at 139.degree. C. or higher is set to 90 seconds, even though reflow is performed only once, the increase in bonding strength is recognized compared with Comparative Examples 1 and 2.
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