JP2005033149A - Method and apparatus for evaluation test of solder wettability of mounting component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus that can precisely measure the solder wettability of a surface-mounting component or the like which has been miniaturized to cope with the miniaturization of electronic/electric products. <P>SOLUTION: A resist film 15 is formed on the upper face of a test jig plate 4 so that solder paste 3, which is printed or applied on the inside of the resist-film pattern 15, can form a sphere without spreading out by wetting when the solder paste is melted. The solder paste 3 is heated to form a melted sphere, and a mounting component 1 is touched to the small solder sphere. The force required to move the mounting component upward by a chuck 2 is detected to find the solder wettability of the mounting component 1. In forming the resist film 15 so that the melted solder may not arbitrarily spread out, the resist film 15 is applied on the outside of a circle located at the center of the test jig plate 4, wherein the diameter of the circle is arbitrarily determined such as 1 mm, 2 mm, or 4 mm, depending on the size of the mounting component to be measured. The quantity of the solder paste 3, which is printed or applied, is determined by considering the size of the melted sphere. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method and an apparatus for evaluating solder wettability of a mounting component used in an electronic / electric product.

  In recent years, as electronic and electrical products such as mobile phones and digital cameras have become more sophisticated, miniaturization has progressed, and along with that, mounting components used in products have also become smaller, and capacitors and resistors such as 1005 and 0603 types have been developed. Has come to be used. It is also extremely important to evaluate solder wetting of a miniaturized mounting component, and various measurement methods are disclosed (for example, see Patent Documents 1, 2, and 3). In addition, lead-free solder used for bonding mounting components to a substrate is in progress. The wettability of printed wiring boards and mounting components and lead-free solder paste is important. Lead-free solder typical tin (Sn) and bismuth (Bi) Sn-Bi eutectic solder on the copper plate Has also been studied in detail (for example, see Non-Patent Document 1).

  In the domestic standards, as a method for evaluating the wettability of solder paste, it is an organization related to the manufacture of electrical and electronic equipment. The Japan Electronic Machinery Manufacturers Association (currently Japan Electronics and Information Industries Association) has a standard (EIAJ ET-7404) Has been enacted. This standard defines the rapid heating test method shown in FIG. 1 and the profile temperature raising test method shown in FIG. The profile test method shown in FIG. 3 is a test method in which the temperature conditions are tested at the same temperature as the actual production line, so that it takes a long time and the wetting output when the solder paste is melted is not stable. For these reasons, the rapid heating test method shown in FIG. 1 is generally used as a simple test method.

  The rapid heating test method of FIG. 1 will be described. (1) is a mounted component, (2) is a mounted component chuck connected to a load meter for measuring the wetting force, (3) is a printed solder paste, (4) is A test jig plate, (5) represents a test jig plate holding mechanism, and (6) represents a molten solder pot. As shown in FIG. 1A, the test method is to print the solder paste (3) on the test jig plate (4) and immerse the mounting component (1) in the solder paste (3) at an arbitrary depth. Next, as shown in FIG. 1B, the melting pot (6) or the sample side is moved, and the test jig plate (4) is immersed in the molten solder. At this time, it is stipulated that the test jig plate (4) must be heated at a heating rate of 70 ° C./second or more.

  FIG. 2 is a waveform of a general wetting output tested by the rapid heating method. In the figure, t0 indicates that when the mounting component is immersed in a solder pot, t1 indicates that the solder paste melts on the mounting component and the wetting occurs. It is when the rise has exceeded zero. According to the standard, the wettability evaluation is performed by measuring the time from t0 to t1 as the time T0 when wetting starts, and measuring the time T1 until reaching t1 to 2 / 3Fmax, and comparing each component relative to the wetness. We are going to evaluate However, in this standard, the temperature rise is 70 ° C./second or more, so the lead-free solder paste has a tin (Sn) + silver (Ag) + copper (Cu) solder and a melting temperature of 217 ° C., and the Sn + Ag solder further Since the temperature becomes high and the solder pot temperature needs to be 245 ° C. to 250 ° C., the time T0 at which wetting begins is 3 seconds or more. The temperature of the test jig plate (4) is affected by heat due to the heat conduction of the test jig plate holding mechanism (5). However, in the JIS C0053 soldering test method (equilibrium method), the sample is immersed in the molten solder and the wetting is evaluated. However, in the explanation II of JIS C0053, the time when wetting starts is preferably 1 to 2.5 seconds. Since solder-plated electronic parts and the like may take 0.3 to 0.6 seconds, it is indicated that the time for starting wetting is preferably 2.5 seconds or less.

  For actual mounted parts, it is known that the starting time of wetting is about 0.5 seconds at most, such as differences in the types of plating of parts, differences in the degree of oxidation, and differences in various solder pastes. Therefore, the time TO at which wetting starts is the time from the time when the sample comes into contact with the molten solder until the point when the solder tries to rise above the surface level of the solder bath. On the other hand, the rapid heating test method is defined as the time from when the test jig plate comes into contact with the solder pot bath surface until the specimen and the solder alloy form a 90 ° contact angle. In the actual measurement of the rapid heating test method, since the solder paste is melted by heating through the test jig plate, the time T0 when wetting starts directly under the influence of the temperature of the test jig plate holding jig. However, it is extremely difficult to determine whether the measured T0 is due to differences in mounted parts or due to heat capacity, heat conduction, etc., although it is a relative comparison.

As an international standard for evaluating the wettability of mounted parts, there is IEC 60068-2-69 (Solderability Testing of Electronic Component for Surface Mount Technology The Thing Bet. Non-patent document 2). In this standard, the solder ball method shown in FIG. 4 is standardized. On the other hand, a solder ball method using solder pellets is also standardized by Japan Electronic Machinery Manufacturers Association as EIAJ ET-7401 as in IEC 60068-2-69. In FIG. 4, (8) is tweezers, (9) is 25 mg or 200 mg solder pellets, (10) is molten pellets, (11) is an aluminum block, (12) is a 2 mm or 4 mm diameter iron core, (13) Represents a heater, and (14) represents a control thermocouple. In the solder ball method, the aluminum block (11) is heated and controlled to an arbitrary temperature such as 235 ° C. or 245 ° C. by the heater (13). Next, a solder pellet (9) having a weight of 25 mg or 200 mg according to the size of the mounted component is placed on the iron core (12). The solder pellet (9) is melted to form a molten solder ball having a diameter of 2 mm or 4 mm as shown in (10). Next, a flux is applied to the mounting component and the solder ball, and the mounting component is immersed in the solder ball in an arbitrary amount, and the wetting force is measured. However, this solder ball method standard is a measurement method using solder pellets and cannot measure solder paste.
JP2001-074630 JP 2002-286612 A JP 2003-168699 A Tanabe Yayoi, Mizutani Seigo, Asagi Zenjiro, Resource Processing Technology, Vol. 48, no. 3, p. 184 (2001) H. Yoshida, M .; E. Warwick, and S.W. P. Hawkins, Inter. Tin Res. Inst. (England), Pub. No. 686.

  Regarding the wettability evaluation test of mounted parts using a solder paste, the only methods standardized by EIAJ ET-7404 are the rapid heating test method and the profile test method. When the test jig plate in the rapid heating test method is immersed and the solder paste is melted, the temperature is unstable due to the heat capacity of the test jig plate and holding metal fittings, although it is necessary to strictly control the temperature. Since the reproducibility of data is poor, the profile method is a test method that tests the temperature conditions at the same temperature as the actual production line, so it takes a long time and the solder paste is melted. There is a problem that the wet output at the time is not stable. It is desired to develop a method and an apparatus that can easily measure without complicated temperature control and that can measure the wetting force between a solder paste and a mounted component at a low cost.

  In view of such circumstances, as a result of intensive research, the inventors first made small spheres with solder paste and then melted the solder paste spheres and mounting components according to the solder pellet measurement method defined in IEC 60068-2-69. As a result, the inventors have invented a method for determining the solder wettability of a mounted component. Conventionally, it is known that in the measurement method of the solder ball method, the smaller the solder ball, the larger the wetting force is output due to the surface tension in the same sample. For this reason, IEC 60068-2-69 determines the size of the mounted component and the size of the solder ball. The present invention relates to a method for measuring the wetting force between a solder paste and a mounting component using a solder small ball produced on a test jig plate by changing the size of a molten solder ball according to the size of the mounting component, and Relates to the device.

  Since this invention measures the solderability test of surface-mounted components using various solder pastes as a molten solder ball of a size that matches the solder paste to the mounted components, compared to conventional measuring methods, It is a method that eliminates the influence of heat, and can be easily and accurately measured.

  The best mode for carrying out the present invention will be described with reference to the drawings. FIG. 5 is a plan view (a) and a side view (b) of the sample jig plate used. In FIG. 5B, (4) is a jig plate, and the resist film (15) is formed on the upper surface so that a sphere can be formed without wetting and spreading when the solder paste is melted. This resist film (15) is applied to the outer part of an arbitrary circle such as a diameter of 1 mm, 2 mm or 4 mm in the center of the jig plate in accordance with the size of the mounted component to be measured. The amount of solder paste to be printed is applied by screen printing or roll coater in consideration of the size of the sphere at the time of melting. What is important here is to determine the resist film diameter and the screen size according to the size of the mounted component. FIG. 6 shows an actual measurement procedure. As shown in FIG. 6A, a test jig plate on which a solder paste is printed is placed on an aluminum block that is controlled by heating. The solder paste is melted to form a spherical shape (FIG. 6B). Next, the mounting component is immersed in a solder ball, and the wetting force is measured. FIG. 7 is an explanatory diagram of the waveform of the wetting output. t0 is the time when the mounting component comes into contact with the molten solder ball, t1 is the time when the mounting component and the solder have a contact angle of 90 °, and T1 = t1−t0 is evaluated as the time when wetting begins.

  The method and apparatus for evaluating solder wettability of mounted components according to the present invention can easily and accurately measure the solder wettability of mounted components that are becoming smaller in response to miniaturization of electronic and electrical products in a relatively short time. This method is advantageous in that it can be easily used by simply modifying a conventional apparatus, and its utility value is very high in the industry.

It is a conceptual diagram of the rapid heating test method. It is explanatory drawing of the output waveform of the wetting force using the rapid heating test method. It is a conceptual diagram of a profile test method. It is a conceptual diagram of the solder ball method. It is explanatory drawing of a test jig board. It is explanatory drawing of an actual measuring method. It is explanatory drawing of the output waveform of the wetting force using the solder ball method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface mount component 2 Connection chuck 3 Printed solder paste 4 Test jig board 5 Jig board holding mechanism 6 Molten solder pot 7 Hot plate 8 Tweezers 9 Solder pellet 10 Molten solder ball 11 Aluminum block 12 Iron core 13 Heater 14 Control thermocouple 15 Resist film

Claims (5)

  Evaluation of wettability between solder paste and minute mounting parts was made by contacting the mounting parts with small spherical molten solder formed by melting the lead-free solder on the surface of a test jig equipped with a heating device. Thereafter, a method and an apparatus for measuring solder wettability, wherein a force for pulling up a mounted component is detected.   A resist film is formed on the test jig plate, and solder paste is printed or applied to the test jig plate, and then heated to melt the solder paste to create solder balls, which are mounted components using the molten solder balls. A solder wettability measuring method and apparatus, characterized in that evaluation of solder wettability is performed.   3. The solder wettability according to claim 1, wherein the solder wettability is evaluated by determining a resist film diameter and a solder paste printing amount according to the size of the mounted component to create a molten solder ball. Measuring method and apparatus.   4. The method and apparatus for measuring solder wettability according to claim 1, wherein the mounted component is a surface-mounted component, and the solder paste is lead-free solder. .   3. The method and apparatus for measuring solder wettability according to claim 2, wherein a resist film formed on the test jig plate and a solder paste film are printed or applied by a screen printing method or a roll coating method.

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