JP2008091838A - Surface mounting substrate and method for mounting component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface mounting substrate and a component mounting method using the substrate for preventing superfluous collapsing of solder at a heat treatment step after component packaging. <P>SOLUTION: The surface mounting substrate 1 includes: substrate electrodes 102-104 formed on a component counter surface portion 1a; wirings 105-107 formed on the surface in a way that they may extend from the substrate electrode; and an insulating surface protective layer 111, in which electrode jointing openings 112-114 are formed so that the substrate electrodes are exposed. The surface protective layer 111 has a through hole portion 115 near to the electrode jointing opening at the component counter surface portion 1a. On the substrate electrode of the substrate, printing agent containing solder and flux is printed, and a component is mounted on the substrate so that the component electrode is located opposite to the substrate electrode, on which printing agent is printed. By heating the substrate, on which the component is mounted, the substrate electrode and the component electrode are jointed with solder. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a surface mounting substrate on which a surface mounting component such as a bare chip component is mounted, and a component mounting method for mounting the surface mounting component on the substrate.

  In recent years, attention has been focused on a method of directly mounting a component such as a bare chip component on a substrate as a component mounting method for a substrate used in an electronic device that is significantly reduced in size and weight. Conventionally, as a component mounting method of this kind, cream solder containing solder and flux is printed on the substrate electrode of the substrate, the component is positioned and mounted on the substrate on which the cream solder is printed, and then the substrate is heated. A method of performing reflow is known (for example, see Patent Document 1).

JP 2001-308268 A

  However, in the conventional component mounting method, when the component is mounted on the substrate on which the cream solder is printed and then heat treatment (reflow) is performed, the solder interposed between the substrate and the component is excessively crushed. There was a point. This excessive crushing of the solder may cause a short circuit between the substrate electrodes adjacent to each other on the substrate, or may cause a change in electrical characteristics by going around to the side of the component where the protective layer of the bare chip component is not formed. It becomes.

  The present invention has been made in view of the above problems, and provides a surface mounting substrate and a component mounting method using the substrate that can prevent excessive crushing of solder due to heat treatment after component mounting. That is.

In order to achieve the above-mentioned object, the invention of claim 1 is directed to a substrate electrode formed on a component-facing surface portion facing a component mounted on the surface, and a wiring formed on the surface so as to extend from the substrate electrode. And an insulating surface protective layer in which an electrode bonding opening is formed so that the substrate electrode is exposed, the surface protective layer being formed on the component facing surface portion. In the vicinity of the electrode bonding opening, a through-hole portion or a thin portion with a reduced thickness is provided.
According to a second aspect of the present invention, in the substrate for surface mounting according to the first aspect, the through-hole portion and the thin portion are formed at positions facing the wiring.
Further, the invention of claim 3 has a substrate electrode group consisting of a plurality of substrate electrodes formed so as to be arranged in a predetermined direction of the component facing surface portion in the surface mounting substrate of claim 1 or 2, The through-hole portion and the thin portion are formed so as to extend along the direction in which the substrate electrodes are arranged in the substrate electrode group.
According to a fourth aspect of the present invention, in the surface mounting substrate according to the first, second, or third aspect, the substrate electrode is formed at a position shifted from the center of the component facing surface portion, and the through-hole portion and the The thin portion is characterized in that it is formed closer to the center than the substrate electrode in the component facing surface portion.
According to a fifth aspect of the present invention, there is provided a substrate electrode formed at a position deviated from the center of a component-facing surface portion on which a component mounted on the surface is opposed, and a wiring formed on the surface so as to extend from the substrate electrode And an insulating surface protective layer in which an opening for electrode bonding is formed so that the substrate electrode is exposed, wherein the wiring is the substrate electrode in the component facing surface portion. It is formed so as to extend from the substrate electrode toward the edge of the component facing surface portion located outside the substrate electrode without passing through the portion on the center side.
According to a sixth aspect of the present invention, a printing agent containing solder and flux is printed on a substrate electrode of a substrate for surface mounting, and the component electrode faces the substrate electrode on which the printing agent is printed. A component mounting method in which a component is mounted on a substrate, and the substrate electrode and the component electrode are joined via the solder by heating the substrate on which the component is mounted. 1, 2, 3, 4 or 5 surface-mounting substrates are used.

  In order to solve the above-described problem of excessive crushing of solder in the heat treatment after component mounting, the present inventors conducted experiments and analyzes on component mounting on a substrate and subsequent heat treatment. As a result, as shown below, it was found that the flux spreading in the gap between the substrate and the component is related to the occurrence of excessive crushing of the solder. The component is mounted on the substrate so that the component electrode faces the substrate electrode on which the printing agent containing solder and flux is printed. When the substrate on which the component is mounted is heated, the printing agent is melted. Here, the flux contained in the printing agent has a melting point lower than that of the solder, and the component facing surface portion of the substrate and the component are close to each other, so that the flux is separated by a capillary phenomenon between the component facing surface portion of the substrate and the component. To expand. With the flux spreading in this way and the attractive force acting between the substrate in contact with the flux and the surface of the component, the component and the substrate can be connected to each other through the flux spreading in the gap without applying external force. A force is generated in a direction in which the two come into close contact with each other. It is considered that the solder of the printing agent sandwiched between the substrate electrode and the component electrode is excessively crushed because the component facing surface portion of the substrate and the component are further brought closer by this adhesion force. The invention of the present application has been made under such experiments and analyses.

In the invention of claim 1, the surface protective layer formed on the surface of the substrate has a through-hole portion or a thin portion with a reduced thickness in the vicinity of the electrode bonding opening in the component facing surface portion. . Since the gap between the surface of the substrate and the surface of the component widens in this through hole or thin portion, the flux spreads due to capillary action in the gap between the component facing surface portion of the substrate and the component during the heat treatment after component mounting. Can be suppressed. Therefore, the adhesive force between the component and the substrate generated by the attractive force between the flux and the substrate and the component can be suppressed.
In the invention of claim 2, the through-hole portion and the thin portion are formed at positions facing the wiring extending from the substrate electrode. At this position, the surface of the surface protection layer is increased by the thickness of the wiring and the gap between the parts tends to be narrowed compared to a location where there is no wiring, so that the flux tends to become a path for spreading the flux. It is possible to avoid the surface of the surface protective layer from becoming higher (a gap between the substrate and the component is reduced) at a position facing the wiring by the through hole portion or the thin portion. Therefore, the spread of the flux due to the capillary phenomenon in the gap between the component facing surface portion of the substrate and the component can be more reliably suppressed.
In the invention of claim 3, the through-hole portion and the thin portion extend along an arrangement direction of a plurality of substrate electrodes constituting the substrate electrode group. As described above, when the through-hole portion extends, the number of the through-hole portions can be reduced and the structure can be simplified as compared with the case where each substrate electrode has the through-hole portion. . In addition, the flux is difficult to spread around the through hole and the like. Therefore, the spread of the flux due to the capillary phenomenon in the gap between the component facing surface portion of the substrate and the component can be more reliably suppressed.
In the invention of claim 4, the through-hole portion and the thin portion are formed closer to the center than the substrate electrode in the component facing surface portion. On the center side of the component facing surface portion, the area where the component and the substrate face each other is wide, and the flux tends to spread. The gap between the surface of the surface protective layer and the component is widened by the through hole portion or the thin portion at the center side of the substrate electrode on the component facing surface portion where the flux is likely to spread. Therefore, the spread of the flux due to the capillary phenomenon in the gap between the component facing surface portion of the substrate and the component can be more reliably suppressed.

  In the invention of claim 5, the wiring of the substrate extends from the substrate electrode toward the edge of the component facing surface portion located outside the substrate electrode without passing through the portion of the component facing surface portion that is closer to the center than the substrate electrode. It is formed as follows. By forming the wiring so that it does not pass through the center side portion of the component facing surface portion in this way, compared to the case where the wiring is formed in the center side portion of the component facing surface portion, only the thickness of the wiring is obtained. The gap between the substrate surface and the component surface is wide. Thereby, the spread of the flux by the capillary phenomenon in the clearance gap between the component opposing surface part of a board | substrate and a component can be suppressed. Therefore, the adhesion force between the component and the substrate generated by the attractive force between the flux and the substrate and the component can be suppressed.

  In the invention of claim 6, the substrate of claim 1, 2, 3, 4 or 5 is used as a substrate for surface mounting on which a component is mounted. In the heat treatment after mounting the component on the substrate, it is possible to suppress the spread of the flux due to the capillary phenomenon in the gap between the component facing surface portion of the substrate and the component.

According to the first to sixth aspects of the present invention, in the heat treatment after mounting the component on the substrate, it is possible to suppress the spread of the flux due to the capillary phenomenon in the gap between the substrate and the component. Thereby, the adhesion force between the component and the substrate generated by the attractive force between the flux and the substrate or the component can be suppressed. Therefore, there is an effect that it is possible to prevent the solder of the printing agent sandwiched between the substrate electrode and the component electrode from being excessively crushed.
In particular, according to the second to fourth aspects of the invention, there is an effect that the spread of the flux due to the capillary phenomenon in the gap between the component facing surface portion of the substrate and the component can be more reliably suppressed.

Hereinafter, an embodiment in which the present invention is applied to a component mounting method for mounting a bare chip component on a substrate will be described.
1A and 1B are a plan view and a side view, respectively, of a bare chip component (hereinafter simply referred to as “bare chip”) mounted on a substrate by the component mounting method according to the present embodiment as viewed from the back side. . This bare chip 10 is a bare semiconductor IC chip before sealing with resin. In the bare chip 10, a plurality of partial electrodes 12 a, 12 b, 13 a, 13 b, 14 a, and 14 b bonded to the substrate electrodes on the substrate are formed on the back surface corresponding to the substrate of the chip body 11. In the example of FIG. 1, component electrode groups each including three component electrodes are formed at both ends in the longitudinal direction on the back surface of the chip body 11. A surface protective layer such as oxidation is formed on the front surface 11s and the back surface 11bs of the bare chip 10. On the other hand, the side surfaces 11a, 11b, 11c, and 11d of the bare chip 10 are cut surfaces when cut from a semiconductor substrate such as a semiconductor wafer, and the internal semiconductor material is exposed.

  2A and 2B are a partial plan view and a cross-sectional view, respectively, of the substrate 1 according to the present embodiment as viewed from the surface. FIG. 2B is a cross-sectional view when cut in the longitudinal direction (lateral direction in the drawing) so as to pass through the center of the component facing surface portion 1a of the substrate 1 shown in FIG. The substrate 1 has a plurality of substrate electrodes 102a, 102b, 103a, 103b, 104a, and 104b, a plurality of wirings 105a, 105b, 106a, 106b, 107a, and 107b on a substrate body 101 made of an insulating material. The surface protective layer 111 is provided.

  The plurality of substrate electrodes 102a, 102b, 103a, 103b, 104a, 104b are formed on the component facing surface portion 1a facing the bare chip 10 so as to correspond to the plurality of component electrodes of the bare chip 10 mounted on the surface. ing. The plurality of substrate electrodes are formed at positions shifted from the center of the component facing surface portion 1a. That is, a substrate electrode group composed of three substrate electrodes is formed at each of both end portions in the longitudinal direction of the component facing surface portion 1a.

  The wirings 105a, 105b, 106a, 106b, 107a, and 107b are each formed in a line shape so as to extend from the corresponding substrate electrode. Among these wirings, the wirings 105a, 105b, 107a, 107b connected to the substrate electrodes 102a, 102b, 104a, 104b located at both ends of each substrate electrode group are opposed to the components located outside the substrate electrodes. It is formed so as to extend toward the edge of the surface portion 1a. On the other hand, the wirings 106a and 106b connected to the substrate electrodes 103a and 103b located at the center of each substrate electrode group are formed so as to pass through a portion of the substrate 1 on the component facing surface portion 1a that is closer to the center than the substrate electrode. .

  The surface protective layer 111 covers and protects the substrate body 101 and the wiring, and is formed of, for example, an insulating resist material for photolithography. In the surface protective layer 111, electrode bonding openings 112a, 112b, 113a, 113b, 114a, and 114b are formed on the substrate electrodes so that the substrate electrodes are exposed. The substrate electrode of the substrate 1 and the component electrode of the bare chip 10 are bonded through these electrode bonding openings.

The surface protective layer 111 has through-hole portions (peeled portions) 115a and 115b in the vicinity of the electrode bonding openings 112a, 112b, 113a, 113b, 114a, and 114b in the component facing surface portion 1a. . In the example of FIG. 2, an opening group including three electrode bonding openings is formed at each of both end portions in the longitudinal direction of the component facing surface portion 1 a. Each of the through-hole portions 115a and 115b is formed so as to extend in the vicinity of the center of the corresponding opening group along the arrangement direction of the electrode bonding openings of the opening group.
In the example of FIG. 2, the through-hole portions 115a and 115b are formed. However, a thin portion in which the thickness of the surface protective layer is reduced may be formed.
The through-hole portion and the thin portion can be formed by, for example, uniformly forming the surface protective layer 111 made of the resist material or the like and then partially removing it by etching or the like.

  Further, the substrate 1 is a substrate in which a large number (for example, several tens to several hundreds) of individual substrates 100 having the same shape and circuit specifications having a predetermined function are arranged as shown in FIG. The substrate 1 is separated into individual substrates 100 after the bare chip 10 and the like are mounted and a predetermined function test is performed. Each of the separated individual substrates 100 is used as a circuit module component having a predetermined function.

  Further, the substrate 1 may be one on which components other than the bare chip 10 are mounted. For example, in addition to the bare chip 10, the substrate 1 may be mounted with a resin-coated chip as a surface-mounted resin-coated component. Examples of the resin exterior chip include parts such as a semiconductor IC sealed with a resin, a resistor, and a capacitor.

  As the substrate 1, a substrate as shown in FIG. 4 may be used. In this substrate 1, the wirings 105a, 105b, 106a, 106b, 107a, 107b are formed as follows. That is, not only the wirings 105a, 105b, 107a, 107b but also the wirings 106a, 106b connected to the substrate electrodes 103a, 103b located at the center of each substrate electrode group are more central than the substrate electrodes in the component facing surface portion 1a of the substrate 1. It is formed so as to extend from the respective substrate electrodes 103a and 103b toward the edge of the component facing surface portion 1a located outside thereof without passing through the side portion.

FIG. 5 is a process diagram showing the main part of the component mounting method according to the present embodiment.
In this component mounting method, first, a cream solder printing process (P1) for printing cream solder as a conductive printing agent on the substrate 1 having the above-described configuration before the bare chip 10 is mounted is executed.

  Next, after the cream solder printing process, a component mounting process (P2) for mounting the bare chip 10 on a predetermined position of the substrate 1 is performed by the component mounting apparatus.

  Next, after the component mounting process of the bare chip 10, a reflow process (P3) of heating the substrate is performed. By this reflow process, the solder is melted together with the flux in the printing agent, and the substrate electrode of the substrate 1 and the component electrode of the bare chip 10 are joined via this solder.

  After the reflow process, a flux cleaning process and an underfill process (not shown) are performed as necessary. The underfill process is a process in which a resin as a filler is filled in the gap between the substrate 1 and the bare chip 10.

  FIG. 6 is a schematic configuration diagram illustrating an example of a printing apparatus that can be used in the cream solder printing process. This printing apparatus prints cream solder 3 as a conductive printing agent on a substrate 1 using a printing mask 2 which is a stencil mask made of a plastic material. In this printing apparatus, the printing mask 2 mounted on the frame member 2 b is fixed by a fixing member 4. The substrate 1 is held on the stage 5 so that the electrode formation surface on which the substrate electrode is formed is the upper surface. Driving means for driving the stage 5 is provided on the lower surface of the stage 5. This driving means is configured by using a stepping motor 6 that can rotate forward and backward, and a vertical movement mechanism 7 that includes a ball screw and a nut (not shown) that is rotationally driven by the motor 6. By controlling the rotation of the stepping motor 6, the stage 5 can be driven in the vertical direction, and the substrate 1 can be moved to a printing position in contact with the printing mask 2 or separated from the printing mask 2.

  Above the stage 5 moved to the printing position, filling means for filling the cream solder 3 into the opening 9 of the printing mask 2 is provided. This filling means includes a squeegee 8 as a filling member for imprinting the cream solder 3 into the opening 9 of the printing mask 2, a squeegee drive mechanism (not shown) for driving the squeegee 8 in the left-right direction in the figure by a drive belt or the like. It is comprised by. The printing mask 2 is provided with openings 9 corresponding to the substrate electrodes on the component facing surface where the bare chip 10 is mounted. For example, in the case of a micro print pattern, the opening 9 is a rectangular opening having a diameter of about 100 to 200 μm or a circular opening having a similar diameter.

  Here, when the opening 9 of the printing mask 2 is a square opening, the inner wall surface substantially perpendicular to the substrate surface (upper surface) of the opening 9 is in the squeegee movement direction (A direction in the figure). The downstream side surface located on the downstream side is preferably an inclined surface inclined with respect to the squeegee movement direction A. Of the inner wall surface of the opening 9 of the printing mask 2, the upstream side surface located on the upstream side in the squeegee movement direction (A direction in the figure) is also the same with respect to the squeegee movement direction (A direction in the figure). It is preferable to use an inclined surface. For example, the inclined surface of the printing mask 2 is inclined by approximately 45 degrees with respect to the squeegee movement direction (A direction in the figure).

  The cream solder used when printing using the fine pattern printing mask 2 is preferably, for example, a solder having an average particle size of 10 μm or less and a flux component content of about 11% by mass. .

In the printing apparatus having the above-described configuration, first, the printing mask 2 is fixed by the fixing member 4, and then the motor 6 is rotationally driven to raise the stage 5 holding the substrate 1 and bring it into contact with the printing mask 2. Then, the cream solder 3 is set on the upper surface of the printing mask 2 and the squeegee 8 is moved in the direction of arrow A, whereby the opening 9 of the printing mask 2 is filled with the cream solder 3 and printed.
Next, in a state where the printing mask 2 filled with the cream solder 3 and the substrate 1 are kept in contact with each other, timing of a waiting time set in advance based on the printing conditions is started. Then, in a state where the predetermined waiting time has passed and the tacking force (adhesive force) of the cream solder 3 has been increased, the motor 6 is driven to rotate and the stage 5 is lowered in the direction of arrow B in FIG. The printing mask 2 is separated. By this separation operation, the cream solder 3 including the bonding material is formed on the substrate electrode of the substrate 1.

  In the component mounting step, for example, mounting can be performed with a component mounting apparatus using a suction nozzle. In this component mounting apparatus, for example, a bare chip held in a reel cassette or tray as a component holding member is sucked by a suction nozzle, and moved and mounted on a component facing surface portion 1a on which paste solder of the substrate 1 is printed. . The suction nozzle incorporates an elastic member such as a spring, and the impact when the bare chip 10 is sucked by the suction nozzle or when the bare chip 10 sucked by the suction nozzle is mounted on the substrate 1 can be reduced. I am doing so. Further, when the bare chip 10 sucked by the suction nozzle is mounted on the substrate 1, the bare chip 10 can be brought into close contact with the paste solder printed on the substrate 1 with a predetermined pressing force.

  7A to 7C are cross-sectional views of the substrate 1 on which the bare chip 10 is mounted by the component mounting method of the present embodiment. These cross-sectional views are cut in the longitudinal direction (lateral direction in the drawing) so as to pass through the center of the component facing surface portion 1a of the substrate 1 shown in FIG. 2 (a), as in FIG. 2 (b). FIG.

  FIG. 7A is a cross-sectional view of the substrate 1 after paste solder printing. In the substrate 1 before printing, electrode bonding openings 113a and 113b are formed in the surface protective film 111 so that the substrate electrodes 103a and 103b are exposed. Paste solders 3a and 3b are printed so as to fill the electrode bonding openings 113a and 113b of the surface protective film 111, respectively. The heights of these printed paste solders 3 a and 3 b are set higher than the surface of the surface protective layer 111. Further, through-hole portions 115a and 115b are formed in the vicinity of the electrode bonding openings 113a and 113b of the surface protective layer 111 from the center.

  FIG.7 (b) is sectional drawing of the board | substrate 1 after bare chip mounting | wearing. The bare chip 10 is mounted so that the component electrodes 12a are in contact with the paste solders 3a and 3b printed on the substrate 1. When the bare chip 10 is mounted, the bare chip 10 is pressed against the paste solders 3a and 3b, so that the heads of the paste solders 3a and 3b are slightly crushed.

  FIG. 7C is a cross-sectional view of the substrate 1 after reflow. In the reflow process, when the substrate on which the bare chip 10 is mounted is heated under predetermined heating conditions, the solders 301a and 301b and the fluxes 302a and 302b in the paste solders 3a and 3b interposed between the electrodes are melted. Here, since the fluxes 302a and 302b have a lower melting point and higher fluidity than solder, they tend to spread along the gap between the substrate 1 and the bare chip 10 by capillary action. Since the through holes 115a and 115b are formed in the vicinity of the electrode bonding openings 113a and 113b in the substrate 1 according to the present embodiment, the fluxes 302a and 302b that try to spread along the gaps pass through the through holes 115a. 115b.

  As described above, according to the present embodiment, the through holes 115 a and 115 b can suppress the spread of the fluxes 302 a and 302 b due to the capillary phenomenon in the gap between the component facing surface portion 1 a of the substrate 1 and the bare chip 10. Therefore, the adhesive force between the bare chip 10 and the substrate 1 generated by the attractive force between the fluxes 302a and 302b and the substrate 1 and the bare chip 10 can be suppressed. Therefore, it is possible to prevent the solders 301a and 301b sandwiched between the substrate electrode 102 and the component electrodes from being excessively crushed.

In particular, according to the present embodiment, the through-hole portions 115a and 115b are formed at positions facing the wirings 106a and 106b extending from the substrate electrode. By using the through-hole portions 115a and 115b, it is possible to avoid an increase in the surface of the surface protective layer 111 at a position facing the wirings 106a and 106b (a reduction in the gap between the substrate and the component).
Further, the through-hole portions 115a and 115b extend along the direction in which the plurality of substrate electrodes 102a, 102b, 103a, 103b, 104a, and 104b constituting each substrate electrode group are arranged. By extending the through-hole portions 115a and 115b in this way, the number of through-hole portions and the like can be reduced and the configuration can be simplified as compared with the case where each substrate electrode has the above-described through-hole portions. it can. Further, the fluxes 302a and 302b are difficult to spread around the through-hole portions 115a and 115b.
The through-hole portions 115a and 115b are formed on the center side of the component facing surface portion 1a with respect to the substrate electrodes 102a, 102b, 103a, 103b, 104a, and 104b. Thereby, the clearance gap between the surface of the surface protective layer 111 and the bare chip 10 becomes wide in the center side rather than the board | substrate electrode of the component opposing surface part 1a where a flux tends to spread.
As described above, in the heat treatment after component mounting, the spread of the fluxes 302a and 302b due to the capillary phenomenon in the gap between the component facing surface portion 1a of the substrate 1 and the bare chip 10 can be more reliably suppressed.

8A to 8C are cross-sectional views of the substrate 1 on which the bare chip 10 is mounted by the component mounting method of the comparative example. 8A is a cross-sectional view of the substrate 1 after paste solder printing, FIG. 8B is a cross-sectional view of the substrate 1 after mounting the bare chip, and FIG. 8C is a cross-sectional view of the substrate 1 after reflow. FIG.
Unlike the substrate 1 of the above embodiment, the substrate used in this comparative example does not include the through-hole portions 115a and 115b. In this case, the fluxes 302a and 302b melted in the reflow process shown in FIG. 8C are caused by a capillary phenomenon so that the gap between the surface of the surface protective layer 11 located above the wirings 106a and 106b of the substrate 1 and the bare chip 10 It spreads along. An attractive force is generated between the fluxes 302a and 302b spreading in this way and the surface of the surface protective layer 111 and the bare chip 10 of the substrate 1 in contact with the flux. This attractive force generates a force in a direction in which the substrate 1 and the bare chip 10 are in close contact with each other via the fluxes 302a and 302b spread in the gap without applying a force from the outside. Due to this adhesion, the component facing surface portion 1a of the substrate 1 and the bare chip 10 are closer to each other, so that the solder 301a and 301b sandwiched between the substrate electrodes 103a and 103b and the component electrodes 13a and 13b are excessively crushed. Will be. This excessively crushed solder 301a, 301b may cause a short circuit between the electrodes. Further, if the excessively crushed solders 301a and 301b reach and come into contact with the side surfaces 11a and 11b where the protective layer of the bare chip 10 is not formed, there is a possibility that the electrical characteristics of the bare chip 10 may be changed. .

9A to 9C are cross-sectional views of the substrate 1 according to another embodiment shown in FIG. 9A is a cross-sectional view of the substrate 1 after paste solder printing, FIG. 9B is a cross-sectional view of the substrate 1 after mounting a bare chip, and FIG. 9C is a cross-sectional view of the substrate 1 after reflow. FIG.
When this substrate 1 is used, the fluxes 302a and 302b melted in the reflow process shown in FIG. 9C try to spread along the gap between the substrate 1 and the bare chip 10 by capillary action. Here, the wirings 106a and 106b of the substrate 1 do not pass through the portion of the component-facing surface portion 1a of the substrate 1 that is closer to the center than the substrate electrodes 103a and 103b, and are components located outside the substrate electrodes 103a and 103b It is formed to extend toward the edge of the opposing surface portion 1a. In this way, by forming the wirings 106a and 106b so as not to pass through the central portion of the component facing surface portion 1a, the wiring is formed in comparison with the case where the wiring is formed in the central portion of the component facing surface portion 1a. The gap between the substrate surface (surface of the surface protective layer) and the surface of the bare chip 10 is wide by the thickness. Thereby, the spread of the fluxes 302a and 302b due to the capillary phenomenon in the gap between the component facing surface portion 1a of the substrate 1 and the bare chip 10 can be suppressed. Therefore, the adhesive force between the bare chip 10 and the substrate 1 generated by the attractive force between the fluxes 302a and 302b and the substrate 1 and the bare chip 10 can be suppressed.

  In the above embodiment, the case where the bare chip 10 is mounted on the substrate 1 has been described. However, the present invention is not limited to the bare chip 10 and can also be applied to the case where other components are mounted. Further, the arrangement and number of substrate electrodes of the substrate 1 that can provide the present invention are not limited to the above-described embodiment.

(A) is the top view which looked at the bare chip mounted on a board | substrate with the component mounting method which concerns on this embodiment from the back surface. (B) is a side view of the bare chip. (A) is the partial top view which looked at the board | substrate concerning this embodiment from the surface. (B) is sectional drawing of the board | substrate. The top view of the whole board | substrate. The partial top view which looked at the board | substrate concerning other embodiment from the surface. (B) is sectional drawing of the board | substrate. Process drawing which shows the principal part of the component mounting method which concerns on this embodiment. The schematic block diagram which shows an example of the printing apparatus which can be used at a cream solder printing process. (A)-(c) is sectional drawing of the board | substrate in each process of the component mounting method which concerns on this embodiment, respectively. (A)-(c) is sectional drawing of the board | substrate in each process of the component mounting method which concerns on a comparative example, respectively. (A)-(c) is sectional drawing of the board | substrate in each process of the component mounting method which concerns on other embodiment, respectively.

Explanation of symbols

1 substrate 1a component facing surface portion 3 (3a, 3b) cream solder 301a, 301b solder 302a, 302b flux 10 bare chip 11 chip body 12a, 12b component electrode 13a, 13b component electrode 14a, 14b component electrode 101 substrate body 102a, 102b substrate Electrode 103a, 103b Substrate electrode 104a, 104b Substrate electrode 105a, 105b Wiring 106a, 106b Wiring 107a, 107b Wiring 111 Surface protective layer 112a, 112b Electrode bonding opening 113a, 113b Electrode bonding opening 114a, 114b Electrode bonding opening 115a, 115b Through hole

Claims (6)

A substrate electrode formed on a component-opposing surface portion facing a component mounted on the surface, a wiring formed on the surface extending from the substrate electrode, and an electrode bonding opening so that the substrate electrode is exposed A surface-mounting substrate having an insulating surface protective layer formed,
The substrate for surface mounting, wherein the surface protective layer has a through-hole portion or a thin portion with a reduced thickness in the vicinity of the electrode bonding opening in the component facing surface portion. The substrate for surface mounting according to claim 1,
The substrate for surface mounting, wherein the through hole portion and the thin portion are formed at positions facing the wiring. The substrate for surface mounting according to claim 1 or 2,
A substrate electrode group comprising a plurality of substrate electrodes formed so as to be aligned in a predetermined direction of the component facing surface portion;
The surface-mounting substrate, wherein the through-hole portion and the thin portion are formed so as to extend along an arrangement direction of the substrate electrodes in the substrate electrode group. In the substrate for surface mounting according to claim 1, 2, or 3,
The substrate electrode is formed at a position shifted from the center of the component facing surface portion,
The substrate for surface mounting, wherein the through-hole portion and the thin portion are formed closer to the center side than the substrate electrode in the component facing surface portion. A substrate electrode formed at a position shifted from the center of the component-facing surface portion facing the component mounted on the surface, wiring formed on the surface extending from the substrate electrode, and the substrate electrode exposed A substrate for surface mounting provided with an insulating surface protective layer having an electrode bonding opening formed thereon,
The wiring is formed so as to extend from the substrate electrode toward the edge of the component facing surface portion located outside the substrate electrode without passing through a portion of the component facing surface portion that is closer to the center than the substrate electrode. A substrate for surface mounting, characterized in that A printing agent containing solder and flux is printed on the substrate electrode of the substrate for surface mounting, and the component is mounted on the substrate so that the component electrode faces the substrate electrode on which the printing agent is printed, A component mounting method for joining the substrate electrode and the component electrode through the solder by heating the substrate on which the component is mounted,
A component mounting method, wherein the substrate for surface mounting according to claim 1, 2, 3, 4 or 5 is used as the substrate.

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