Solder ball and columnar pin mixed mounting method

Abstract

The present invention enables dissimilar connection members such as solder balls and columnar pins to be mounted on electrodes provided on the surface of a wafer or printed circuit board, and also enables the dissimilar connection members to be reflowed all at once. [Solution] A solder paste containing flux and solder particles is printed only on the pin mounting electrode portion, and heated at a predetermined temperature for a predetermined time to obtain a flat surface of only solder particles on the pin mounting electrode portion.Flux is then printed to a predetermined thickness on the pin mounting electrode portion and the ball mounting electrode portion, a solder ball is mounted on the ball mounting electrode portion via a ball metal mask, and a columnar pin is mounted on the pin mounting electrode portion via a pin metal mask, and these are then reflowed all at once.

Description

[Technical Field]

[0001] The present invention relates to a solder ball and columnar pin mixed mounting method that can mount and mount different types of connecting members, that is, solder balls and columnar pins, on electrodes provided on the same surface of a wafer or printed circuit board. [Background technology]

[0002] The conventional method for mounting this type of solder ball or columnar pin involves applying an adhesive such as flux or solder paste to an electrode portion (hereinafter referred to as the "PAD portion") on the surface of a wafer or printed circuit board (hereinafter referred to as the "work") using a transfer device or screen printer, and then mounting the solder ball or columnar pin on the PAD portion.

[0003] However, with conventional mounting methods for solder balls and columnar pins, it is difficult to mount solder balls and columnar pins on pads located on the same surface of the workpiece due to differences in the properties of the adhesive and the shapes, dimensions, and weights of the solder balls and columnar pins, and so it has been common to mount solder balls and columnar pins using two separate methods: a method for mounting solder balls and a method for mounting columnar pins.

[0004] In the former process, i.e., the "method of mounting solder balls," flux, which acts as an adhesive, is applied to the PAD portion of the workpiece using a transfer device or the like, and then the solder balls are mounted on the PAD portion using a metal foil metal mask specially designed for mounting solder balls, and then reflowed (Patent Document 1). The flux used here has a predetermined adhesiveness and acts as a fixing agent.

[0005] Next, in the latter process, i.e., the "method of mounting pins," a solder paste that acts as an adhesive is applied to the PAD portion of the workpiece using screen printing or the like, and then a metal mask made of metal foil specially designed for mounting columnar pins is used, and the columnar pins are mounted on the PAD portion through the openings in the metal mask, followed by reflow (Patent Document 2). The columnar pins are called Cu-Pins, Cu-Posts, Cu-Columns, etc. and are made of copper or other materials and are formed into a very small cylindrical shape. The adhesive used in the above process may be a material having a predetermined adhesiveness and conductivity, such as the solder paste described above, Cu paste, Ag paste, or the like. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-108908 [Patent Document 2] Japanese Patent Application Publication No. 2024-144328 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0007] However, since the flux and solder paste used as adhesives have different properties, and the solder balls and columnar pins to be mounted on the PAD section have different shapes, dimensions, and weights, conventional mounting methods have had to be carried out separately as a "solder ball mounting method" and a "pin mounting method." Therefore, in the conventional mounting method, the processes from printing flux to mounting the solder balls on the PAD portion of the work and reflowing using the "solder ball mounting method" and the processes from printing solder paste to mounting the columnar pins on the PAD portion of the work and reflowing using the "pin mounting method" had to be carried out separately, which made the process complicated and had the disadvantage of taking time for the processing steps.

[0008] The present invention has been made in consideration of the drawbacks of the prior art described above, and aims to provide a solder ball and columnar pin mixed mounting method that enables dissimilar connection components, such as solder balls and columnar pins, to be mounted on a PAD portion provided on the surface of a workpiece, and also enables these dissimilar connection components to be reflowed all at once. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention provides a solder ball and columnar pin mixed mounting method that mounts dissimilar connection members, such as solder balls and columnar pins, on electrodes provided on a workpiece and enables the dissimilar connection members to be reflowed all at once, comprising: a step of printing a solder paste containing flux and solder particles only on the pin mounting electrode portion on which the columnar pin is to be mounted, and then heating the printed circuit board at a predetermined temperature for a predetermined time to obtain a flat surface of only the solder particles in the solder paste on the pin mounting electrode portion; a step of printing flux to a predetermined thickness on the pin mounting electrode portion and the ball mounting electrode portion after the step is completed; a step of using a metal mask for balls, the metal mask having openings formed therein in accordance with the positions of the electrode portions for ball mounting, and mounting the solder balls on the electrode portions for ball mounting through the openings; a step of using a metal mask for pins, the metal mask having openings formed in accordance with the positions of the pin-mounting electrode portions, and mounting the columnar pins on the pin-mounting electrode portions through the openings; It is characterized by comprising: [Effects of the Invention]

[0010] According to the solder ball and columnar pin mixed mounting method of the present invention, it is possible to mount dissimilar connection members, such as solder balls and columnar pins, on a PAD section provided on a workpiece, and to reflow the dissimilar connection members all at once, which has the advantage of simplifying the processing steps and enabling the dissimilar connection members to be mounted and reflowed in a short time. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a plan view showing a workpiece to which a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention is applied; [Figure 2] 1 is a side view showing a state in which balls and columnar pins are mounted on a workpiece by a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention; [Figure 3] 1A and 1B are cross-sectional views illustrating a solder paste printing step in a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention. [Figure 4] 1 is a plan view of a main part shown for explaining a solder paste printing step in a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention; FIG. [Figure 5] 1 is a cross-sectional view of a main part for explaining a solder paste heating step in a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention; [Figure 6] 1 is a plan view of a main part for explaining a state in which solder particles in a solder paste are smoothed by a solder paste heating step in a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention; FIG. [Figure 7] 7 is a plan view of a main part for explaining a state in which the solder particles in the solder paste are smoothed by a solder paste heating process in a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention, and is an enlarged partial view of FIG. [Figure 8] 1 is a cross-sectional view of a main part for explaining a flux printing step in a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention; [Figure 9] 1 is a plan view of a main part for explaining a state in which a ball is mounted on a ball pad portion by a ball mounting step in a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention. FIG. [Figure 10] 1 is a plan view of a main part for explaining a state in which balls are mounted on PAD portions by a ball mounting step in a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention; FIG. [Figure 11]1 is a cross-sectional view of a main part for explaining a step of mounting a columnar pin in a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention; [Figure 12] FIG. 10 is a plan view of a main part for explaining a state in which solder balls are mounted on ball PAD portions in a solder ball mounting process and columnar pins are mounted on PAD portions in a columnar pin mounting process in a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention. [Figure 13] FIG. 10 is a cross-sectional view of a main part showing a state in which a columnar pin is mounted on a PAD portion by a columnar pin mounting process in a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention, and a solder ball is mounted on a ball PAD portion by a solder ball mounting process, and the two-type connection member is reflowed all at once. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing a workpiece to which a solder ball and columnar pin mounting method according to an embodiment of the present invention is applied. In FIG. 1, reference numeral 1 denotes a workpiece (wafer or printed circuit board), and three rows of pad portions (electrode portions) are provided around the outer side surface of the workpiece 1. In this embodiment, the PAD in the innermost row is the PAD section 2 for mounting balls (sometimes simply referred to as PAD section 2), the PAD section in the next middle row is the PAD section 3 for mounting balls (sometimes simply referred to as PAD section 3), and the PAD section in the outermost row (on the outer periphery of the work 1) is the PAD section 4 for mounting pins (sometimes simply referred to as PAD section 4). In the case of FIG. 1, electronic components and the like (not shown) are mounted within the area surrounded by the PAD section 2, the middle row PAD section 3, and the outer row PAD section 4 of the workpiece 1.

[0013] 2 is a cross-sectional view taken along line AA' in FIG. 1, showing a state in which solder balls and columnar pins are mounted on a workpiece by a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention. 2, solder balls 6, 6 are mounted on the inner row pad portion 2 and the middle row pad portion 3 of the workpiece 1. Pillar pins 7, 7 are mounted on the outer row pad portions 4, 4.

[0014] As shown in FIG. 2, solder balls 6, 6 are mounted on PAD sections 2, 3, and pillar pins 7, 7 are mounted on PAD section 4, which are realized by a solder ball and pillar pin mixed mounting method according to an embodiment of the present invention. Therefore, the gist of the solder ball and columnar pin mixed mounting method will be described below. This mixed mounting method is composed of the following steps a to e. [Step a] A process in which a solder paste containing flux and solder particles is printed only on the pin mounting PAD portion 4 on which the columnar pin 7 is mounted, and then heated at a predetermined temperature for a predetermined time, thereby obtaining a flat surface of the solder particles in the solder paste on the pin mounting PAD 4. [Step b] After the above steps are completed, a step of printing flux to a predetermined thickness on the pin mounting pad portion 4 and the ball mounting pad portions 2 and 3. [Step c] A step of using a metal mask for balls, which has openings formed in accordance with the positions of the ball mounting pads 2, 3, and mounting the solder balls 6, 6 on the ball mounting pads 2, 3 through the openings. [Step d] A step of mounting the columnar pins 7 on the pin mounting pads 4 through the openings using a pin metal mask having openings formed in accordance with the positions of the pin mounting pads 4. [Step e] A step of performing a collective reflow process in which the solder balls 6, 6 are mounted on the ball mounting pads 2, 3 and the pillar pin 7 is mounted on the pin mounting pad 4.

[0015] Next, an embodiment of the present invention will be described in detail. <Process a> First, the step a will be described with reference to FIGS. FIG. 3 is a cross-sectional view illustrating a solder paste printing step in the solder ball and columnar pin mixed mounting method according to the embodiment of the present invention. 3, the workpiece 1 is sucked and placed on a suction jig 5. A metal mask 8 for printing solder paste (hereinafter also referred to as the printing metal mask 8) is placed on the workpiece 1. Solder paste 9 is placed on the printing metal mask 8, and the solder paste 9 is printed on the pin pad portion 4 by sliding a squeegee 10 over the printing metal mask 8. Here, the printing metal mask 8 has printing openings 11, 11, ... that are aligned with the positions of the PAD portions 4, 4, ..., so that the solder paste 9, 9, ... is printed on the PAD portions 4, 4, ..., but the solder paste 9 is not printed on the PAD portions 2 and 3. The solder paste 9 used here is a mixture of flux and solder particles, and is made of a material that has a certain level of adhesiveness and is conductive, so it can be used sufficiently as an adhesive.

[0016] FIG. 4 is a plan view of a main part shown for explaining a state in which solder paste has been printed on a pad portion by a solder paste printing step in a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention. 4, reference numerals 9a, 9a,... indicate solder paste layers printed on the pads 4, 4,... of the work 1. Also, the state is shown in which no solder paste is printed on the pads 2, 2,... and the pads 3, 3,... of the work 1.

[0017] FIG. 5 is a cross-sectional view of a main part for explaining a solder paste heating step in the solder ball and columnar pin mixed mounting method according to the embodiment of the present invention. In the printing process described above, solder paste layers 9a are printed on the pad portions 4 of the workpiece 1. The workpiece 1 is placed in a heating device to heat the solder paste layers 9a. This heating is carried out at a temperature at which the flux in the solder paste layers 9a becomes fluid, flattens, and finally volatilizes, but at a temperature at which the solder particles in the solder paste layers 9a do not melt. Specifically, the solder paste layers 9a are heated in a heating device at a predetermined temperature, for example, 100°C, for a predetermined time, for example, 30 seconds, causing the flux components in the solder paste layers 9a to liquefy and flatten, after which they volatilize. As a result, on the PAD portions 4, 4,..., the flux components in the solder paste layers 9a, 9a,... are liquefied and flattened, and the solder particles are also flattened.The flux is then heated further and volatilizes, and the solder particles in the solder paste layers 9a, 9a,... are left unmelted on the pin PAD portions 4, 4,..., resulting in flat surfaces 9c, 9c,... of flattened solder particles. Then, when the heating step of the solder paste is completed, the workpiece 1 is cooled.

[0018] Fig. 6 is a plan view of a main part showing a state in which the flux in the solder paste has been volatilized by a workpiece heating process and the solder particles have been smoothed and flattened in an embodiment of the present invention. Fig. 7 is a further enlarged plan view of Fig. 6 showing a state in which the solder particles in the solder paste have been smoothed and flattened in a solder paste heating process in an embodiment of the present invention. As shown in these figures, on the PAD portions 4, 4,... of the work 1, solder particle flat surfaces 9c, 9c,... are shown, which are solder particles that have remained in the solder paste layers 9a, 9a,... and have been flattened into a film. Also, it is shown that the solder paste 9 is not printed on each of the pad portions 2, 2, . . . and each of the pad portions 3, 3, .

[0019] <Process b> FIG. 8 is a cross-sectional view of a main part for explaining a flux printing step in the embodiment of the present invention. 8, a flux printing metal mask 12 is placed on the workpiece 1. This flux printing metal mask 12 has openings 13 aligned with the positions of the pads 2, 2,..., the pads 3, 3,..., and the pads 4, 4,... On the flux printing metal mask 12, flux 14 is printed all at once on the pads 2, 2,..., the ball pads 3, 3,..., and the pads 4, 4,..., using a squeegee 15. At this time, it is desirable that the amount of printed flux be such that it covers each of the PAD portions 2, 2,..., each of the PAD portions 3, 3,..., and each of the PAD portions 4, 4,... of the workpiece 1. Note that reference numeral 14a indicates a layer of flux printed on each of the PAD portions 2, 2,..., each of the PAD portions 3, 3,..., and each of the PAD portions 4, 4,...

[0020] <Process c> FIG. 9 is a cross-sectional view illustrating a ball mounting step in the solder ball and columnar pin mixed mounting method according to the embodiment of the present invention. 9, a solder ball mounting metal mask 16 is placed on the workpiece 1. This solder ball mounting metal mask 16 has openings 17 that match the positions of the pad portions 2, 2,... and pad portions 3, 3,... The solder ball mounting metal mask 16 is placed on the workpiece 1 in a state where it is aligned so that the openings 17 match the positions of the pad portions 2, 2,... and pad portions 3, 3,... Solder balls 17, 17, ··· are mounted on the pads 2, 2, ··· and pads 3, 3, ··· through the openings 17, 17, ··· of the solder ball mounting metal mask 16 arranged in this manner. The solder ball mounting metal mask 16 does not have openings at the positions of the pads 4, 4, . . . , so that the solder balls 6, 6, . . . are mounted only on the pads 2, 2, . . . and pads 3, 3, . . .

[0021] FIG. 10 is a plan view of a main part for explaining a state in which balls are mounted on PAD portions in a ball mounting step in a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention. 10 shows a state in which solder balls 6 are mounted on pads 2, 2,... and pads 3, 3,... on the work 1. Naturally, solder balls 6 are not mounted on pads 4, 4,... on the work 1.

[0022] <Process d> FIG. 11 is a cross-sectional view of a main part for explaining a step of mounting a columnar pin in a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention. In FIG. 11, a pin mounting metal mask 18 is placed on the workpiece 1, and columnar pins 7, 7, . . . are placed on the pin mounting metal mask 18 and mounted on the pad sections 4, 4, . The mounting metal mask 18 has openings 19 aligned with the positions of the pads 4. In addition, recesses 20 of a predetermined area are formed on the work 1 side of the mounting metal mask 18 by half etching or the like to match the positions of the solder balls 6 already mounted on the pads 2 and 3 in step c so as not to come into contact with them. At this time, it is desirable to make the height of the solder balls 6 lower than the height of the columnar pins 7. Using such a pin mounting metal mask 18, the pin mounting metal mask 18 is aligned, and the columnar pins 7 are mounted on the pad portions 4 through the openings 19 of the pin mounting metal mask 18.

[0023] FIG. 12 is a plan view of a main part for explaining a state in which solder balls are mounted on ball PAD portions in a solder ball mounting process and columnar pins are mounted on PAD portions in a columnar pin mounting process in a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention. Figure 12 shows the state in which solder balls 6, 6, ... are mounted on PAD portions 2, 2, ... and PAD portions 3, 3, ... of work 1, and the state in which columnar pins 7, 7, ... are mounted on PAD portions 4, 4, ... of work 1.

[0024] <Process e> FIG. 13 is a cross-sectional view of a main part showing a state in which, in a solder ball and columnar pin mixed mounting method according to an embodiment of the present invention, solder balls are mounted on ball PAD portions in a solder ball mounting process, columnar pins are mounted on PAD portions in a columnar pin mounting process, and these are reflowed all at once. 13, solder balls 6 are mounted on the pads 2, 2, and 3, 3 of the work 1, and post pins 7 are mounted on the pads 4, 4, of the work 1, and then the work 1 is turned upside down. This causes the post pins 7 to be adjusted to be more vertical, and also adjusts the positions of the solder balls 6, 6, etc. The reference numeral 22 denotes a spacer, which is a member for keeping the workpiece 1 at a fixed distance from the base 23. In the state shown in FIG. 13, the solder balls 6, 6, ··· and the columnar pins 7, 7, ··· can be reflowed all at once.

[0025] According to the solder ball and columnar pin mixed mounting method of the embodiment of the present invention, it is possible to mount dissimilar connection members, such as solder balls and columnar pins, on a PAD portion provided on a workpiece, and to reflow the dissimilar connection members all at once, which has the advantage of significantly simplifying the processing steps and enabling the dissimilar connection members to be mounted and reflowed in a short time. It should be noted that various modifications are possible within the scope of the present invention. [Explanation of symbols]

[0026] 1 Work 2,3 Ball mounting pad 4-pin mounting pad 5. Suction jig 6 solder balls 7 Post pin 8 Metal mask for solder paste printing 9. Solder paste 13 Metal mask for flux printing 14 Flux 16 Metal mask for solder ball mounting 18-pin mounting metal mask

Claims

[Claim 1] A solder ball and columnar pin mixed mounting method that mounts dissimilar connection members, such as solder balls and columnar pins, on electrodes provided on a wafer or a printed circuit board and enables the dissimilar connection members to be reflowed all at once, comprising: a step of printing a solder paste containing flux and solder particles only on the pin mounting electrode portion on which the columnar pin is mounted, and then heating the printed circuit board at a predetermined temperature for a predetermined time to obtain a flat surface of only the solder particles in the solder paste on the pin mounting electrode portion; a step of printing flux to a predetermined thickness on the pin mounting electrode portion and the ball mounting electrode portion after the step is completed; a step of using a metal mask for balls, the metal mask having openings formed in accordance with the positions of the electrode portions for ball mounting, and mounting the solder balls on the electrode portions for ball mounting through the openings; a step of using a metal mask for pins, the metal mask having openings formed in accordance with the positions of the pin-mounting electrode portions, and mounting the columnar pins on the pin-mounting electrode portions through the openings; 1. A solder ball and columnar pin mixed mounting method comprising:

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