JP2003273306A - Lead frame substrate and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent solder or a flux from flowing into an area other than joints when electronic parts, etc., are joined by reflow soldering. <P>SOLUTION: On a substrate on which surface mounting parts are joined by reflow soldering, an oxide film for preventing the flow of solder is formed on an area 12 without the necessity of soldering, which is the area other than that on which the electrodes of the surface mounting parts are mounted. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a board on which electronic parts and the like are mounted, and more particularly to a lead frame board and a manufacturing method capable of preventing a solder flow when soldering electronic parts and the like.

[0002]

2. Description of the Related Art A conventional method of manufacturing a lead frame substrate will be described with reference to FIG. 5. First, a lead frame 1 is formed from a metal plate by etching or punching by a press, and an electronic component having this lead frame pattern is formed. After applying solder to the mounting parts, etc., electronic parts etc. 2 are mounted on this solder applying part, the electronic parts etc. are joined to the lead frame pattern by soldering means such as reflow soldering, and finally the pattern and the outer frame. The hanging pin 3 that connects the two was cut at the cut portion 3a.

However, according to the above method, when soldering an electronic component or the like to the lead frame pattern, solder or flux flows into a portion other than the joint portion of the electronic component or the like, as shown by hatching in FIG. As shown in FIG. 6, a sufficient fillet was not formed in the joint portion of the electronic component or the like, and there was a problem in reliability.

When solder or flux flows into the hanging pin 3, not only the thickness of this portion increases, but also cracks occur in electronic parts, especially thin and weak ceramic capacitors when cutting by pressing. There was also a problem. There is also a method of cutting with a laser as a means of hanging pin cutting other than pressing, but in this case it is necessary to enter the coordinates of the cut part,
If the number of cutting points increases, the work becomes troublesome and the work efficiency deteriorates.

Therefore, in order to deal with this, Japanese Patent Laid-Open No. 5-1
In Japanese Patent No. 67234, a solder resist is formed on the electrode portion except for the soldering portion, a recess in which the solder is placed is press-molded on the electrode portion, or the spread of the solder is prevented at the peripheral portion of the electrode portion. It is described that the groove is press-molded.

As another means, as shown in FIG. 7, a slit 4 is formed in the lead frame pattern,
It has been proposed to prevent the inflow of solder or the like into areas other than the joint.

[0007]

However, the formation of the solder resist requires the addition of a new material, which increases the number of materials. Further, the formation of the recessed portion and the groove portion requires press molding, which is troublesome, and as shown in FIG. 8, hot plate type reflow soldering using the hot plate 5 as a heating source is used for soldering electronic components and the like. When adopted, if the heights of the bottoms of the recesses and the groove 6 are different, the heat from the hot plate 5 may not be uniformly transferred to the recesses 6 and the solder may not melt.

On the other hand, in the proposed example in which the slits for preventing the solder flow are formed, the pattern is inevitably complicated, and accordingly, the die for forming the lead frame by the press is also complicated. The mold becomes expensive.
Moreover, in order to facilitate the penetration of solder, it is necessary to make the width of the slit approximately the same as the plate thickness of the lead frame, which makes it difficult to miniaturize the pattern.

The present invention has been made in view of the above problems, and is a lead frame substrate capable of preventing solder or flux from flowing into a portion other than a joint portion when soldering an electronic component or the like, and its manufacture. The purpose is to provide a method.

[0010]

In order to achieve the above-mentioned object, the present invention sets a first area requiring soldering and a second area not requiring soldering on a component mounting surface. The second region is characterized in that an oxide film forming portion where an oxide film for preventing solder flow is formed and an oxide film non-forming portion where an oxide film is not formed are provided.

Therefore, according to the present invention, since the oxide film is formed, it is possible to prevent the solder and the flux from flowing into a portion other than the joint portion when the electronic parts and the like are joined by the solder. Sufficient fillets can be formed at the joints without any problems in quality and reliability. In addition, since solder or the like does not flow into the hanging pin, the hanging pin can be easily cut by a press, and at that time, cracks do not occur in the mounted electronic parts such as a ceramic capacitor. Furthermore, since it only forms an oxide film,
It is easy to manufacture and does not require any special material, and therefore does not increase the number of materials. Furthermore, since the oxide film plays a role of insulation between electronic components, the components can be arranged in close proximity to each other, and the components can be mounted up to the peripheral edge of the substrate.
It is possible to increase the density of parts and downsize the lead frame pattern. Furthermore, since the lead frame is not provided with recesses or grooves, no unevenness is produced on the lead frame.Therefore, when soldering electronic components, etc., when using hot plate type reflow soldering with a hot plate as a heating source, Since the heat from the hot plate is evenly transferred to the lead frame, there is no risk of non-melting of the solder. Furthermore, since the lead frame is not provided with slits, it is possible to further reduce the size of the pattern.

Further, according to the present invention, an oxide film for preventing a solder flow is formed on a portion of a substrate on which surface mount components are joined by reflow soldering, in which a portion of the surface mount component where electrodes are mounted or a soldering unnecessary portion other than connection terminals is not soldered. Is formed.

Therefore, according to the present invention, when the surface mount components are joined by the reflow soldering, the solder and the flux are prevented from flowing into a portion other than the joint portion. Therefore, a sufficient fillet is formed in the joint portion. It can be formed without any problems in quality and reliability. Also, since solder or the like does not flow into the hanging pins, the hanging pin can be easily cut by pressing, and at that time, cracks do not occur in the surface-mounted components such as mounted ceramic capacitors. . Further, since only the oxide film is formed, it is easy to manufacture, and no special material is required. Therefore, the number of materials is not increased. Furthermore, since the oxide film plays a role of insulation between electronic components and the like, the components can be arranged in close proximity to each other, and the components can be mounted up to the peripheral edge of the substrate. The size of the lead frame pattern can be reduced. Furthermore, since the lead frame is not provided with recesses or grooves, no unevenness is produced on the lead frame.Therefore, when soldering electronic components, etc., when using hot plate type reflow soldering with a hot plate as a heating source, Since the heat from the hot plate is evenly transferred to the lead frame, there is no risk of non-melting of the solder.
Furthermore, since the lead frame is not provided with slits, it is possible to further reduce the size of the pattern.

Further, according to the present invention, after the lead frame is oxidized by heating to form an oxide film on the entire surface of the lead frame, the oxide film in the first region and the oxide film non-forming portion or the surface mount component is formed. It is characterized in that the oxide film on the portion on which the electrode is mounted and the connection terminal is removed.

Therefore, according to the present invention, since the lead frame is simply heated to remove the oxide film in a predetermined portion, the solder flow preventing means can be easily obtained.

Furthermore, according to the present invention, an oxide film is formed on the entire surface of the oxide film forming portion of the second region or the soldering unnecessary portion, and the first region is a portion where an electrode of a surface mount component is mounted. It is conceivable that an oxide film is formed only around the electrode mounting portion, or that an oxide film is formed only around the electrode mounting portion of the surface mount component.

Therefore, according to the present invention, since only the oxide film in the first region is removed, the substrate can be easily manufactured.

[0018]

DETAILED DESCRIPTION OF THE INVENTION A lead frame substrate according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a lead frame 10. In the figure, the white part excluding the shaded portion shows the first region 11 where soldering is required, and the shaded portion shows the second region 12 where soldering is not required.

The second region 12 is provided with an oxide film forming portion 12a in which an oxide film for preventing solder flow is formed and an oxide film non-forming portion (not shown) in which an oxide film is not formed, which will be described later. There is.

The first region 11 shows a portion where the electrodes of the surface mount component 13 are mounted, and solder is applied to this portion. No surface mount component is mounted in the second region 12. Therefore, no solder is applied to this area.

A connection terminal may be formed on the peripheral portion of the second region 12, but no oxide film is formed on this connection terminal. The aforementioned oxide film non-forming portion (not shown) means this connection terminal.

FIG. 2 shows a state in which the actual surface component 13 is joined to the lead frame pattern by reflow soldering. In the figure, the black part shows the solder after the reflow soldering.

As described above, the solder after the reflow soldering does not flow into the second region 12 where the oxide film is formed. Therefore, as shown in FIG. 3, a sufficient fillet 14 is formed. Further, since it does not flow into the hanging pin 15 which connects the pattern and the outer frame, the hanging pin can be easily cut by pressing. that time,
No cracks are generated in the surface mount component.

FIG. 4 shows another embodiment. In the first embodiment, the oxide film is formed over the entire surface of the second region 12 (excluding the terminal when the connection terminal is formed), but in the second embodiment, the surface mount component 13 is formed. An oxide film is formed only around the portion where the electrodes are mounted. The other configuration is the same as that of the first embodiment, and thus the description thereof is omitted.

Next, a method of manufacturing the lead frame substrate according to the present invention will be described. First, a lead frame is formed by etching or punching with a press from a metal plate such as copper or a copper alloy which is easily oxidized.

Either by placing the lead frame in a constant temperature bath at about 200 ° C. or by directly mounting it on a hot plate heated at about 200 ° C.
The lead frame is heated to oxidize the entire surface of the lead frame to form an oxide film.

The second region 12 (excluding the terminal when the connection terminal is formed) where soldering is not required is masked with photoresist or the like, and the first region 11 (the connection terminal is formed) by etching. In that case, the oxide film is removed from (including the terminal).

By this method, a fine circuit pattern of about several microns can be formed, and thereby a metal substrate that can be mounted at high density can be formed.

[0030]

According to the present invention, the component mounting surface is provided with a first region where soldering is required and a second region where soldering is not required, and the second region is provided with oxidation for preventing solder flow. Since the oxide film forming part where the film is formed and the oxide film non-forming part where the oxide film is not formed are provided, when soldering electronic parts etc. with solder, it is possible to prevent solder and flux from flowing into parts other than the bonding part. As a result, a sufficient fillet can be formed at the joint, and no problem occurs in quality and reliability.

Further, since solder or the like does not flow into the hanging pin, the hanging pin can be easily cut by pressing, and at the same time, cracks may be generated in the mounted electronic parts such as ceramic capacitors. There is no.

Further, since only the oxide film is formed, it is easy to manufacture, and no special material is required. Therefore, the number of materials is not increased. Furthermore, since the oxide film plays a role of insulation between electronic components and the like, the components can be arranged in close proximity to each other, and the components can be mounted up to the peripheral edge of the substrate. The size of the lead frame pattern can be reduced.

Furthermore, since the lead frame is not provided with recesses or grooves, no unevenness is produced on the lead frame. Therefore, hot plate type reflow soldering using a hot plate as a heat source is employed for soldering electronic components and the like. In doing so, the heat from the hot plate is evenly transferred to the lead frame, so there is no risk of solder non-melting. Furthermore, since the lead frame is not provided with slits, it is possible to further reduce the size of the pattern.

Further, according to the present invention, in a substrate for joining surface mounting components by reflow soldering, an oxide film for preventing solder flow is formed on a portion of the surface mounting component where electrodes are mounted or a portion where soldering is unnecessary except for connection terminals. As a result, solder and flux are prevented from flowing into the parts other than the joint when the surface mount components are joined by reflow soldering.Therefore, a sufficient fillet can be formed in the joint. It can be done without any problems in quality and reliability.

Also, since solder or the like does not flow into the hanging pins, the hanging pins can be easily cut by pressing, and at the same time, cracks are generated in the surface-mounted components such as the mounted ceramic capacitors. Never. Furthermore, since it only forms an oxide film, it is easy to manufacture and does not require any special material.
Therefore, the number of materials is not increased.

Furthermore, since the oxide film plays a role of insulating between electronic parts and the like, the parts can be arranged in close proximity to each other, and the parts can be mounted up to the peripheral edge of the substrate. It is possible to increase the density and reduce the size of the lead frame pattern.

Furthermore, since the lead frame is not provided with recesses or grooves, no unevenness is produced on the lead frame. Therefore, hot plate type reflow soldering using a hot plate as a heat source is adopted for soldering electronic components and the like. In doing so, the heat from the hot plate is evenly transferred to the lead frame, so there is no risk of solder non-melting. Furthermore, since the lead frame is not provided with slits, it is possible to further reduce the size of the pattern.

Further, according to the present invention, an oxide film is formed on the entire surface of the lead frame by oxidizing the lead frame by heating, and then the oxide film in the first region and the oxide film non-forming portion or the electrode of the surface mount component. In order to remove the oxide film on the mounting portion and the connection terminal, the solder flow preventing means can be easily obtained by simply heating the lead frame to remove the oxide film on the predetermined portion.

[Brief description of drawings]

FIG. 1 is a plan view of a lead frame substrate according to the present invention before mounting surface mount components.

FIG. 2 is a plan view of the same after mounting the surface mount components.

FIG. 3 is also an enlarged view showing the fillet of FIG.

FIG. 4 is a plan view of the lead frame substrate according to another embodiment after mounting the surface mount components.

FIG. 5 is a plan view showing a conventional solder flow state.

FIG. 6 is also an enlarged view showing the fillet with insufficient solder in FIG. 5;

FIG. 7 is a plan view showing another conventional example.

FIG. 8 is an explanatory view of soldering a board manufactured by a conventional example by reflow soldering.

[Explanation of symbols]

10 lead frame 11 First area 12 Second area 12a Oxide film forming part 13 Surface mount components

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yuzo Matsushita             Shiokyo-ku, Kyoto-shi, Kyoto Prefecture             801 Kudo-cho Omron Co., Ltd. (72) Inventor Seiji Oka             Shiokyo-ku, Kyoto-shi, Kyoto Prefecture             801 Kudo-cho Omron Co., Ltd. F term (reference) 5F067 AA16 BB00 DD10 DF20

Claims (6)

[Claims] 1. A first region requiring soldering and a second region not requiring soldering are set on a component mounting surface, and an oxide film for preventing solder flow is formed in the second region. A lead frame substrate comprising an oxide film forming portion and an oxide film non-forming portion on which an oxide film is not formed. 2. An oxide film for preventing solder flow is formed on a portion of a surface-mounted component to be joined by reflow soldering, in a portion where the electrode is mounted or a portion of the surface-mounted component that does not require soldering except a connection terminal. Lead frame board characterized by. 3. An oxide film is formed on the entire surface of the lead frame by oxidizing the lead frame by heating, and then an oxide film in the first region and the oxide film non-forming portion or an electrode of the surface mount component is mounted. A method for manufacturing a lead frame substrate, characterized in that an oxide film on a portion and a connection terminal is removed. 4. The lead frame substrate according to claim 1, 2 or 3, wherein an oxide film is formed on the entire surface of the oxide film forming portion of the second region or the soldering unnecessary portion. 5. The lead frame substrate according to claim 1, wherein the first region is set to a portion where an electrode of a surface mount component is mounted, and an oxide film is formed only around the electrode mounting portion. The manufacturing method. 6. The lead frame substrate according to claim 2, wherein an oxide film is formed only around a portion of the surface-mounted component on which an electrode is mounted, or the manufacturing method thereof.