JP2013197273A - Electronic component manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic component manufacturing method which can restrain all of damage to boards, residuals of solder balls, and poor fillet formation even when electronic elements are mounted on a printed wiring board built with a low melting point board such as a PET or PEN by irradiating it with near-infrared laser light from the reverse side of the board.SOLUTION: An electronic component manufacturing method of the present invention involves mounting electronic elements on a printed wiring board built with a board made of resin whose melting point is 280°C or less and having a wiring pattern thereon. The manufacturing method includes a step of supplying solder, a placement step of placing terminals for the electronic elements into position, and a step of soldering the electronic elements to the printed wiring board by irradiating it with near-infrared laser light. In the placement step, the wiring pattern is restricted in width to 2 mm or less within at least 2 mm on both sides in the extension direction of the wiring pattern from the center in width of the terminal, and the shortest distance from an end portion in the width direction on one side of the wiring pattern to the terminal is defined to be 0.5 mm to 1.6 mm.

Description

  The present invention relates to a method for manufacturing an electronic component.

  When an electronic element is mounted on a substrate and a printed wiring board having a wiring pattern on the substrate to obtain an electronic component, a main method for soldering the electronic element to the printed wiring board is a reflow method. This is because an electronic element is mounted on the wiring pattern on the surface of the printed wiring board via solder, and then the printed wiring board is transported into a reflow furnace and hot air at a predetermined temperature is blown to the printed wiring board in the reflow furnace. By attaching, the solder paste is melted and the electronic element is soldered to the printed wiring board. The temperature in the reflow furnace is 280 ° C. or higher.

  In order to automate the soldering in such a reflow furnace, a reel-to-reel system can be used by using a flexible substrate. In that case, as described in Patent Document 1, it is common to use a substrate mainly composed of a polyimide resin. This is because the polyimide resin is a high melting point material exceeding 400 ° C. and has heat resistance sufficient to withstand the temperature in the reflow furnace. That is, in mounting on a flexible substrate by the reflow method, a substrate made of a high heat resistant material having a melting point exceeding 280 ° C. has to be used.

Japanese Patent Application Laid-Open No. 08-222831

  However, polyimide resin is expensive and has high hygroscopicity, which causes fluctuations in electrical characteristics. On the other hand, it is desirable to use a substrate made of a material such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), which has low hygroscopicity and is inexpensive, but these base materials have a melting point of 280 ° C. or lower. Since it is inferior in heat resistance, it is difficult to solder by the reflow method.

  Then, when the present inventors examined, if near infrared laser light with a wavelength of 900-980 nm is irradiated toward the solder from the back surface of a board | substrate, it will consist of materials with melting | fusing point like 280 degrees C or less like PET and PEN. It has been found that electronic devices can be soldered to a printed wiring board using a substrate.

  However, when soldering is performed by irradiating near infrared laser light from the back side of the substrate, the back side of the substrate may be damaged, or some of the solder balls in the solder may remain undissolved, It has been found that a fillet having a good shape that can ensure connection reliability may not be formed. FIGS. 7A to 7C are schematic diagrams showing these problems caused by soldering, all of which are formed on a flexible substrate 524 made of a material having a melting point of 280 ° C. or lower. This is a result of mounting the electronic element 508 on the printed wiring board 522 having 526 through the solder 504 and irradiating the near-infrared laser light from the back surface of the substrate 524 and soldering. FIG. 7A shows a case where the substrate 524 is greatly damaged when the near-infrared laser light is irradiated to the extent necessary to sufficiently melt the solder 504. FIG. 7B shows a case where a part of the solder ball remains as a result of the solder 504 moving on the wiring pattern 526 to the outside of the laser easy heating zone. FIG. 7C shows a case where a fillet having a shape that can sufficiently ensure long-term connection reliability is not formed because the area of the wiring pattern is small and the contact area between the solder and the wiring pattern is narrowed. The long-term connection reliability can be sufficiently secured by the fillet shape in which the fillet is in sufficient contact with the terminal side surface and the contact angle is less than 45 °. Further, in this specification, the contact angle of the fillet means an angle formed by the solder mirror surface at the fillet skirt tip and the wiring pattern.

  Therefore, in view of the above-mentioned problems, the present invention can damage a substrate even when an electronic device is mounted on a printed wiring board using a substrate having a low melting point such as PET or PEN by irradiating near-infrared laser light from the back of the substrate. An object of the present invention is to provide a method for manufacturing an electronic component capable of suppressing both remaining solder balls and defective fillet formation.

  As a result of intensive studies by the present inventors in order to achieve the above object, by optimizing the shape of the wiring pattern around the soldering site, the circuit board has a melting point of 280 ° C. or less without damaging it. The present inventors have found that the solder can be melted, and further, the remaining of the solder balls and poor fillet formation can be sufficiently suppressed, and the present invention has been completed. This invention is based on said knowledge and examination, The summary structure is as follows.

  An electronic component manufacturing method according to the present invention is an electronic component manufacturing method in which an electronic element is mounted on a printed wiring board having a substrate made of a resin having a melting point of 280 ° C. or less and a wiring pattern on the substrate. A method of supplying solder onto the wiring pattern; a mounting step of mounting terminals of the electronic element on the solder; and from the back side of the printed wiring board toward the solder. Irradiating near-infrared laser light to melt the solder, and soldering the electronic element to the printed wiring board. In the placing step, the terminal of the wiring pattern A land portion having a width of 2 mm or less is provided within a range of at least 2 mm on both sides of the wiring pattern in the extending direction from the center of the width in the extending direction, and the wiring pattern on the land portion is provided. Characterized by a 0.5mm~1.6mm the shortest distance to the terminal from one widthwise end portion of the over down.

  In the present invention, in the placing step described above, the circuit may branch from one end in the width direction of the land portion along a direction perpendicular to the extending direction of the wiring pattern. The width of the circuit at the branch position is preferably 1 mm or less.

  In this invention, it is preferable that the terminal step is placed by pressing the terminal against the solder so that the solder is biased toward the one end in the width direction.

  In the present invention, the substrate is preferably long and flexible.

  In the present invention, the terminal arrangement of the plurality of electronic elements is not limited, but in a reel-to-reel type substrate, two terminals of each element are arranged along a direction perpendicular to the longitudinal direction of the substrate. It is preferable to implement as described above.

  According to the present invention, when an electronic device is mounted on a printed wiring board using a substrate having a low melting point such as PET or PEN by irradiating near-infrared laser light from the back surface of the substrate, damage to the substrate, It was possible to suppress both remaining and poor fillet formation.

It is a schematic diagram which shows the apparatus used for the manufacturing method according to this invention. It is a schematic diagram which expands and shows the part of the soldering by laser irradiation in the apparatus shown in FIG. It is a model top view of the wiring pattern around a soldering site | part which shows the manufacturing method of the electronic component according to this invention. (A)-(D) are sectional drawings in the AA position of Drawing 3 (A)-(D), respectively. It is a model top view of the electronic component manufactured by the manufacturing method according to this invention. It is a model top view of the electronic component which has the branch circuit manufactured with the electronic component according to this invention. (A)-(C) are schematic sectional drawings of the soldering part of a comparative example, respectively. 6 is a top view of a wiring pattern in Experimental Example 1. FIG.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.

(Electronic component manufacturing equipment)
With reference to FIG. 1 and FIG. 2, the manufacturing apparatus 100 of the electronic component which can implement this invention is demonstrated. The manufacturing apparatus 100 manufactures an electronic component 112 by mounting the electronic element 108 on a printed wiring board 122 having a substrate 124 and a wiring pattern 126 on the substrate 124. In this specification, in accordance with JIS C 5603 and IEC60914, “printed wiring board” includes a substrate and a wiring pattern formed on the substrate, and does not include an electronic element to be mounted.

  First, the manufacturing apparatus 100 includes a supply device 102 that supplies the solder 104 onto the wiring pattern 126 of the printed wiring board. The supply device 102 is not particularly limited, but is preferably a non-contact dispenser. Although not shown in detail, the non-contact dispenser connects a tank for containing solder, a discharge nozzle for discharging the solder to the printed wiring board from a position separated from the printed wiring board, and the tank and the discharge nozzle. A connecting portion for supplying solder from the discharge nozzle to the discharge nozzle, and a control portion for controlling them. According to the supply device 102, a predetermined amount of solder can be supplied from a position separated from the printed wiring board. Therefore, compared to a device that supplies solder in a state where the printed wiring board and the discharge nozzle are in contact with each other, it is possible to suppress the take-back of the solder and to suppress time loss due to the vertical movement of the discharge head. Moreover, since the discard amount of solder is small, it is preferable from an environmental viewpoint.

  Next, the manufacturing apparatus 100 includes a mounting device 106 that mounts the electronic element 108 on the solder 104. The mounting device 106 is not particularly limited, and for example, a known mounting device such as a chip mounter can be used. In FIGS. 1 and 2, the terminals of the electronic elements are not shown.

  Next, the manufacturing apparatus 100 includes a laser 110. As shown in FIG. 2, the laser 110 irradiates near infrared light from the back surface 122A side of the printed wiring board toward the solder 104 on which the electronic element 108 is placed. The irradiated light passes through the substrate 124 and reaches the wiring pattern 126, heats the wiring pattern 126, and the solder 104 is melted. In this way, the electronic element 108 is soldered to the printed wiring board 122.

  The laser 110 is not particularly limited as long as the wavelength can be set in the range of 900 to 980 nm. For example, a semiconductor laser having a wavelength can be used. In addition, in this specification, “the back surface of the printed wiring board” means that the back surface of the pair of main surfaces of the printed wiring board when the surface on which the electronic element is mounted is the front surface, that is, the electronic device is mounted. It means the surface that does not.

  The manufacturing apparatus 100 may have an inspection apparatus 114. For example, when an LED is used as the electronic element 108, an actual spot check device can be used.

  As shown in FIG. 1, the printed wiring board 122 is stretched between a pair of reels 118 and 120, and the printed wiring board 122 is run between the two reels. A reel-to-reel system in which a plurality of electronic elements 108 are continuously mounted on the plate 122 can be employed.

(Method for manufacturing electronic parts)
Next, a method for manufacturing an electronic component according to an embodiment of the present invention will be described with reference to FIGS. 3 (A) to 3 (D) are schematic top views of the wiring pattern around the soldering site, and FIGS. 4 (A) to 4 (D) are respectively A-A in FIGS. 3 (A) to (D). It is sectional drawing in a position. FIG. 5 is a schematic top view of an electronic component manufactured by the manufacturing method according to the present invention. In the manufacturing method of the present invention, an electronic component 112 is formed by mounting an electronic element 108 on a printed wiring board 122 having a substrate 124 made of a resin having a melting point of 280 ° C. or less and a wiring pattern 126 on the substrate 124. 108 is a manufacturing method.

  Here, the present embodiment is characterized in that the terminal 128 of the electronic element 108 is placed on the wiring pattern 126 so that the shape of the wiring pattern around the soldering site satisfies a predetermined condition. Specifically, in the placement step of placing the terminal 128 of the electronic element 108 on the solder 104, as shown in FIGS. 3B and 4B, one end in the width direction of the wiring pattern 126 is obtained. The terminal 128 is pressed against the solder 104 and placed so that the solder 104 is biased toward the portion 130, and the extension of the wiring pattern 126 is further extended from the center 128 A of the terminal 128 in the extending direction of the wiring pattern 126. A land portion 126A having a wiring pattern 126 with a width W of 2 mm or less is provided within a range of at least 2 mm on both sides in the present direction, and the terminal from the width direction end portion 130 in the direction in which the solder is biased from the terminal on the land portion 126A. The shortest distance D up to 128 is 0.5 mm to 1.6 mm.

  Hereinafter, the technical significance of adopting the above characteristic steps of the present invention will be described with specific examples together with the effects. As described above, the present inventors soldered a substrate made of a material having poor melting point and having a melting point of 280 ° C. or less by irradiating near infrared laser light of 900 nm to 980 nm from the back side of the printed wiring board. I found out that it can be attached. However, such soldering has the problems described above.

  First, the inventors have conceived that the substrate damage shown in FIG. 7A can be solved by making the wiring pattern area around the soldering portion as small as possible. This is because if the area of the wiring pattern is large, the heat dissipation effect in the wiring pattern is large, the solder heating efficiency is deteriorated, and it is necessary to irradiate the solder for a long time or at a high output for melting the solder. As a result of studies by the inventors, heat radiation due to the wiring pattern becomes a problem in the range from the center 128A of the terminal 128 in the extending direction of the wiring pattern 126 to at least 2 mm on both sides in the extending direction of the wiring pattern 126. In addition, it was found that if the wiring pattern has a width W of 2 mm or less within at least the range, damage to the substrate having a melting point of 280 ° C. or less can be remarkably suppressed.

  Moreover, the following knowledge was acquired about the remaining of the solder ball shown in FIG. 7B and the inability to form a fillet having a good shape with which long-term connection reliability shown in FIG. 7C can be obtained.

  The solder 104 is a so-called cream solder, and includes a solder ball, a resin component called a flux, and a solvent. When the solder 104 is irradiated with laser light, first, the flux is reduced in viscosity, and the solder ball is entrained and flows on the wiring pattern (FIG. 4C). Next, it was found that the solder balls located within the easy heating range of the laser irradiation melt and form a fillet, but the solder balls that flowed out of the easy heating range remain without melting and do not form a fillet. When the distance D shown in FIG. 3B is long, this phenomenon occurs, so that solder balls remain as shown in FIG. 7B. Moreover, when the distance D is long, as a result of the solder flowing too much, the fillet is not sufficiently in contact with the side surface of the terminal, and a fillet with long-term connection reliability cannot be formed. According to the study by the present inventors, in the terminal size and the amount of solder used in this embodiment, by setting D to 1.6 mm or less, as shown in FIG. It was found that the fillet was sufficiently in contact with the side surface of the terminal.

  On the other hand, if the distance D is too short, it becomes easy to melt the solder. However, as shown in FIG. 7C, the contact area between the solder and the wiring pattern is reduced, and the contact of the solder is reduced. Since the angle is 45 ° or more, it is impossible to form a fillet with high long-term connection reliability. As a result of investigations by the inventors, in the terminal size and the amount of solder used in the present embodiment, when the distance D is 0.5 mm or more, the contact angle is less than 45 °, and the long-term connection reliability can be obtained. It has been found that fillets can be formed.

  That is, if D is less than 0.5 mm, there is no solder ball remaining, but the contact angle of the fillet becomes 45 ° or more, and long-term connection reliability decreases. If the thickness exceeds 1.6 mm, fillet wetting is not formed and solder balls remain. Based on the above findings, the present inventor has completed the present invention.

  Next, an embodiment according to the method of manufacturing an electronic component of the present invention will be specifically described. First, the printed wiring board 122 is prepared. The printed wiring board 122 includes a substrate 124 and a wiring pattern 126.

  The substrate 124 preferably has a thickness of 10 to 100 μm and a laser transmittance range of 5% or more. The material of the substrate 124 is preferably a resin having a melting point of 220 ° C. to 280 ° C., more preferably 250 ° C. to 280 ° C., for example, PET and / or PEN. Substrates containing PET and / or PEN are subject to large deformations and hydrolysis due to heat in the conventional reflow method. However, according to the present invention, hydrolysis, melting and scorching are suppressed. Can be used. If the substrate 124 is long and flexible, a reel-to-reel mounting device can be used. Thereby, productivity of an electronic component can be improved.

  The wiring pattern 126 is preferably a copper foil having a thickness of 5 μm to 70 μm. This is because if it is thinner than 5 μm, solder balls may be scattered during laser irradiation, and if it is thicker than 70 μm, it may be difficult to melt the solder due to laser irradiation from the back surface.

  Next, the solder 104 is supplied onto the wiring pattern 126 (FIGS. 3A and 4A). As the solder, for example, a known solder such as cream solder or solder paste can be used. The amount of solder supplied can be adjusted as appropriate depending on the terminal shape of the electronic component to be used. For example, when a terminal portion having a depth of 0.2 to 1.5 mm, a width of 1 to 3 mm, and a height of 0.1 to 3 mm is placed on the wiring pattern, 0.01 mg to 5.0 mg is preferable. Further, 0.1 mg to 3.0 mg is preferable.

  Next, the terminal 128 of the electronic element 108 is placed on the solder 104 (FIGS. 3B and 4B). The portion of the terminal 128 of the electronic element 108 used in the present invention located on the wiring pattern 122 has a depth of 0.2 to 1.5 mm, a width of 1 to 3 mm, and a height of 0.1 to 3 mm. , The effect of the present invention can be obtained with certainty. Note that the electronic element 108 is more preferably an LED. In the conventional reflow soldering, the entire component is heated, so that the fluorescent agent and internal wiring of the LED are deteriorated and a sufficient lifetime cannot be obtained. However, according to the soldering according to the present invention, This is because a long-life LED component can be manufactured. However, the electronic element 108 is not limited to the LED, but includes a chip capacitor, a chip resistor, a sensor component such as a CCD (charge coupled device), a BGA (ball grid array) of general semiconductor components, a QFP (Quad Flat Package), and a CSP (CSP). (Chip size package) or the like.

  In this specification, a wiring pattern within a range of at least 2 mm on both sides in the extending direction of the wiring pattern 126 from the center 128A in the extending direction of the wiring pattern 126 of the terminal 128 is referred to as a land portion 126A. In the placement step, the terminal 128 is placed so that the width W of the land portion 126A is 2 mm or less. Further, the terminal 128 is placed so that the shortest distance D from one width direction end portion 130 to the terminal 128 on the land portion 126A is 0.5 mm to 1.6 mm. When the terminal 128 is placed on the solder 104, the terminal 128 is soldered so that the solder 104 is biased toward the one end 130 in the width direction of the wiring pattern 126 as shown in FIG. 4B. It is preferable to place it by pressing against 108.

  When the reel-to-reel method is adopted, as shown in FIG. 5, the plurality of electronic elements 108 are arranged so that two terminals 128 of each electronic element 108 are aligned along a direction perpendicular to the longitudinal direction of the substrate 124. In addition, it is preferable to mount on the wiring pattern 126. When the printed wiring board is wound around the reel, the substrate 124 is curved in the longitudinal direction. However, if the printed circuit board is mounted as shown in FIG. 5, peeling of the solder and electronic components from the printed wiring board can be suppressed.

  Next, near infrared laser light is irradiated from the back surface 122A side of the printed wiring board toward the solder 104 to melt the solder 104 (FIGS. 3C and 4C) to form a fillet. Then, the electronic element 108 is soldered to the printed wiring board 122 (FIGS. 3D and 4D). Here, the near-infrared laser light has a wavelength in the range of 900 nm to 980 nm, an output of 15 W or less, an irradiation diameter on the substrate surface of 0.1 mm to 2.0 mm, and once per soldering of one terminal. Irradiate. In the case of the solder amount described above, the general irradiation time is 0.1 to 1.0 seconds.

  Further, as shown in FIG. 6, the circuit 132 can be branched to form, for example, a connection confirmation circuit. In that case, in the mounting process, the circuit 132 branches from the width direction end portion 130 in the direction in which the solder is biased from the terminal in the land portion 126A along the direction perpendicular to the extending direction of the wiring pattern 126. The width at the circuit branch position 134 is preferably 1 mm or less. This is because if it is 1 mm or less, the flow of solder to the branched circuit 132 can be suppressed.

  In order to further clarify the effects of the present invention, comparative evaluations in which experiments of Examples and Comparative Examples described below were conducted will be described.

<Experimental example 1: Evaluation of substrate damage>
(Sample preparation)
A substrate made of PET having a melting point of 255 ° C. (Mitsubishi Resin Co., Ltd .: W400) was used. This substrate has a thickness of 50 μm and has flexibility. First, the copper foil was etched on the substrate by a known method to form a wiring pattern as shown in FIG. Between the pair of 10 mm square copper foils separated by the distance Y shown in Table 1, a wiring pattern with a thickness of 35 μm having a linear copper foil with a width W shown in Table 1 is formed, and printed wiring A plate was made.

  Next, the LED was mounted. Using a non-contact jet dispenser (Musashino Engineering Co., Ltd .: Jet Master), 1.8 mg of cream solder (Senju Metal Industry Co., Ltd .: Eco Solder Paste S70G) was added to the center of the linear copper foil (+ in FIG. 8). ).

  Next, the terminal of the LED element (Samsung: 5630) was mounted on the cream solder using a mounter (Okuhara Electric Co., Ltd .: tabletop mounter). At this time, the terminal was pressed against the solder and placed so that the cream solder was biased toward one side in the width direction of the wiring pattern. The terminal portion on the wiring pattern was 0.4 mm × 1.3 mm × 0.25 mm (depth × width × height). The shortest distance D from the end in the width direction in the direction in which the solder was biased from the terminal to the terminal was fixed at 1.6 mm. Next, using a semiconductor laser with a wavelength of 920 nm (manufactured by Hamamatsu Photonics: LD irradiation device 15W type), the laser output is adjusted to 12.5 W, the irradiation diameter on the substrate surface is adjusted to 0.4 mm, and printed wiring Soldering was performed by irradiating laser light from the back side of the plate toward the solder until the solder melted.

(Evaluation)
In Examples and Comparative Examples, substrate damage was evaluated. When the substrate has a damage of 25 μm or more, it is shown in Table 1 as x, and when there is no damage, it is shown as ◯. There was no substrate damage when the wiring pattern was 2 mm within the range of 2 mm (land part) on both sides of the wiring pattern extending direction from the center of the width of the terminal in the extending direction of the wiring pattern. When there was a part exceeding 2 mm in width, substrate damage occurred. In either case, there was no remaining solder balls or defective fillet formation.

<Experimental example 2: Evaluation of fillet shape and solder ball remaining>
(Sample preparation)
A flexible substrate made of PET having a melting point of 255 ° C. and having a thickness of 50 μm (Mitsubishi Resin Co., Ltd .: W400) was used. First, a copper foil was etched on a substrate by a known method to form a wiring pattern made of a copper foil having a length of 100 mm, a width of Table 2 and a thickness of 35 μm, and a printed wiring board was produced.

  Next, the LED was mounted. 1.8 mg of cream solder (Senju Metal Industry Co., Ltd .: Eco Solder Paste S70G) was supplied onto the wiring pattern on the printed wiring board using a non-contact jet dispenser (Musano Engineering Co., Ltd .: Jet Master).

  Next, the terminal of the LED element (Samsung: 5630) was mounted on the cream solder using a mounter (Okuhara Electric Co., Ltd .: tabletop mounter). At this time, the terminal was pressed against the solder and placed so that the cream solder was biased toward one side in the width direction of the wiring pattern. The terminal portion on the wiring pattern was 0.4 mm × 1.3 mm × 0.25 mm (depth × width × height). The shortest distances D from the terminals in the width direction in the direction in which the solder is biased from the terminals to the terminals are as described in Table 2, respectively. Next, using a semiconductor laser with a wavelength of 920 nm (manufactured by Hamamatsu Photonics: LD irradiation device 15W type), the laser output is adjusted to 12.5 W, the irradiation diameter on the substrate surface is adjusted to 0.4 mm, and printed wiring Soldering was performed by irradiating laser light from the back side of the plate toward the solder until the solder melted.

(Evaluation)
The fillet shape was evaluated visually and with a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd .: automatic contact angle meter). Table 2 shows the case where the fillet is in contact with almost the entire side surface of the terminal having a height of 0.25 mm and the contact angle is less than 45 °, and “X” otherwise. Table 2 shows the results of microscopic observation of the presence or absence of remaining solder balls. Further, Table 2 shows the presence or absence of damage of 25 μm or more on the substrate.

  When the distance D was 0.5 mm to 1.6 mm, the fillet shape was good, and no solder balls remained. When the distance D was 1.85 mm or more, part of the solder flowed out of the easy heating zone, and the solder balls remained. In this connection, the fillet shape has a low long-term connection reliability as shown in FIG. When the distance D was 0.4 mm, no solder balls remained, but the fillet contact angle stood up and the fillet shape became a shape with low long-term connection reliability as shown in FIG. When the width W of the wiring pattern was 2 mm or less, there was no substrate damage.

<Experimental example 3: Branch circuit width evaluation>
(Sample preparation)
A flexible substrate made of PET having a melting point of 255 ° C. and having a thickness of 50 μm (Mitsubishi Resin Co., Ltd .: W400) was used. First, the copper foil is etched on the substrate by a known method to have a copper foil wiring pattern having a width W of 2 mm, and one of the land portions is perpendicular to the extending direction of the wiring pattern. A circuit was branched from the end in the width direction, a wiring pattern having a thickness of 35 μm was formed in the shape of FIG. 6 with a width at the branching position of the circuit being 0.9 mm, and a printed wiring board was manufactured.

  Next, the LED was mounted. 1.8 mg of cream solder (Senju Metal Industry Co., Ltd .: Eco Solder Paste S70G) was supplied onto the wiring pattern on the printed wiring board using a non-contact jet dispenser (Musashino Engineering Co., Ltd .: Jet Master).

  Next, an LED element (Samsung: 5630) was placed on the cream solder using a mounter (Okuhara Electric Co., Ltd .: tabletop mounter). At this time, the terminal was pressed against the solder so that the cream solder was biased toward the end in the width direction having the branch circuit of the wiring pattern. The terminals on the wiring pattern were 0.4 mm × 1.3 mm × 0.25 mm (depth × width × height). The distance D was 1.6 mm. Next, using a semiconductor laser with a wavelength of 920 nm (manufactured by Hamamatsu Photonics: LD irradiation device 15W type), the laser output is adjusted to 12.5 W, the irradiation diameter on the substrate surface is adjusted to 0.4 mm, and printed wiring Soldering was performed by irradiating a laser beam once for 0.5 seconds toward the solder from the back side of the plate.

(Evaluation)
The presence or absence of remaining solder balls was evaluated by microscopic observation. The solder did not flow out to the branched circuit, the solder balls did not remain, and the solder could be soldered with a fillet with a shape that could ensure long-term connection reliability. There was no substrate damage.

  According to the present invention, when an electronic device is mounted on a printed wiring board using a substrate having a low melting point such as PET or PEN by irradiating near-infrared laser light from the back surface of the substrate, damage to the substrate, It is possible to provide a method for manufacturing an electronic component capable of suppressing both remaining and defective fillet formation.

DESCRIPTION OF SYMBOLS 100 Electronic component manufacturing apparatus 102 Supply apparatus 104 Solder 106 Mounting apparatus 108 Electronic element 110 Laser 112 Electronic component 114 Inspection apparatus 116 Line 118 Reel 120 Reel 122 Printed wiring board 122A Back surface of printed wiring board 124 Substrate 126 Wiring pattern 126A Land part 128 terminal 128A terminal width center 130 one width direction end 132 branched circuit 134 circuit branch position

Claims (5)

An electronic component manufacturing method for mounting an electronic element on a printed wiring board having a substrate made of a resin having a melting point of 280 ° C. or lower and a wiring pattern on the substrate,
Supplying solder onto the wiring pattern;
A placement step of placing the terminals of the electronic elements on the solder;
To the solder from the back side of the printed wiring board, irradiating near infrared laser light, melting the solder, and soldering the electronic element to the printed wiring board;
Have
In the previous placement process,
From the center of the width of the terminal in the extending direction of the wiring pattern, within a range of at least 2 mm on both sides of the extending direction of the wiring pattern, a land portion having a width of 2 mm or less is provided for the wiring pattern.
The method of manufacturing an electronic component, wherein a shortest distance from one end in the width direction of the wiring pattern to the terminal on the land portion is set to 0.5 mm to 1.6 mm. In the previous placement process,
The method of manufacturing an electronic component according to claim 1, wherein the terminal is pressed against and placed on the solder so that the solder is biased toward the one end in the width direction. In the previous placement process,
A circuit branches from one end in the width direction of the land portion along a direction perpendicular to the extending direction of the wiring pattern,
The method for manufacturing an electronic component according to claim 1, wherein a width of the circuit at a branch position is 1 mm or less.   The method of manufacturing an electronic component according to claim 1, wherein the substrate is long and flexible.   5. The method of manufacturing an electronic component according to claim 4, wherein the plurality of electronic elements are mounted such that two terminals of each element are aligned along a direction perpendicular to a longitudinal direction of the substrate.