JP2000114680A - Mounting circuit board and battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slit which becomes a flux relief section when a lead plate is soldered to a pad electrode on the surface of the pad electrode. SOLUTION: The variation of the peeling strength of a lead plate 50 is reduced and the plate 50 is stably fixed by providing a slit 57 which becomes a flux relief section when the lead plate 50 is soldered to the pad electrode of a mounting substrate 51 on the surface of the pad electrode 55.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounted circuit board and a battery, and more particularly to an improvement of a lead plate mounted on the mounted circuit board for preventing malfunction of a charge / discharge circuit mounted on the battery.

[0002]

2. Description of the Related Art In recent years, various electronic devices have been reduced in size and weight, and a large number of devices that are light and easy to carry even when they are carried have been commercialized. A battery is used for portable equipment because commercial AC cannot be used as a power source for driving. As the battery to be used, a battery having a high energy density that can withstand continuous use for a long time and discharge by a large current is desired.

[0003] Therefore, a pack battery in which a plurality of secondary batteries such as a nickel-cadmium battery and a nickel-hydrogen battery are combined has been widely used. The secondary battery can be repeatedly used by charging and discharging, and a high-voltage or high-capacity power supply can be easily obtained by combining a plurality of the secondary batteries. Further, when the battery packs are combined, the shape is matched to the shape of the battery mounting portion of the electric device, whereby a battery pack suitable for the device can be formed.

[0004] Recently, lithium ion batteries having higher energy density than nickel-cadmium batteries have been developed. However, since a lithium ion battery is liable to be deteriorated when overcharged or overdischarged, a protection circuit for preventing overcharge or overdischarge is required.

[0005] Therefore, in a battery pack containing a lithium ion battery, a printed circuit board or the like constituting a protection circuit is housed together with the battery.

[0006] Japanese Patent Application Laid-Open No. 08-329913 describes the above matters in detail.
This will be described with reference to FIGS. 10 is a box-shaped main body case, and 11 is a lid. The body case 10 and the lid 11 constitute the outer shape of the battery pack. Body case 10
Has a step portion 12 formed in a portion to which the lid 11 is attached, and by attaching the lid 11 thereto, the end face of the main body case 10 and the lid 11 become flat to complete a clean rectangular parallelepiped outer shape. .

A pair of terminal windows 13 are opened in the lateral side plate of the main body case 10, and a rib 1 is formed in the longitudinal side plate.
4 are provided. Of the four corners of the body case 10, two corners on the side of the side plate where the ribs 14 are provided are provided with reverse storage preventing portions 15. The remaining two corners are almost right-angled corners. Reference numeral 20 denotes a prismatic lithium ion battery. The battery 20 has an outer shape in which an electrode portion 22 protrudes from a rectangular outer can 21. The electrode portion 22 is a negative electrode (or a positive electrode), and the outer casing 21 is all a positive electrode (or a negative electrode). Reference numeral 23 denotes insulating paper, which has a hole so that the electrode portion 22 is exposed. The insulating paper 23 is fixed to the battery 20 with a double-sided tape or the like. This insulating paper 23 is used to connect a lead plate 42 (described later) to the electrode portion 2.
2 prevents the short circuit due to the contact between the lead plate 42 and the outer can 21 when welding is performed.

Reference numeral 30 denotes a first printed board, and 31 denotes a second printed board. Each of the two printed boards 30 and 31 has an elongated plate shape, and a circuit element 33 is mounted on a central portion of the first printed board 30 excluding an end region 32. As for the circuit element 33, a tall element and a short element are mixed, and there is a slight space between each element.
The circuit element 33 is connected to the lithium-ion battery 20 to form a protection circuit for protecting the battery from overcharging and overdischarging.

Reference numeral 35 denotes a thermistor whose resistance value changes in accordance with a change in temperature. The thermistor 35 is connected in series with the battery 20 to prevent an excessive current from flowing through the battery 20. The thermistor 35 is insulated from the battery outer can 21 by insulating paper 36. The insulating paper 36 is fixed to the thermistor 35 with a double-sided tape.

The two substrates 30, 31 and the thermistor 3
5 and the width of the insulating paper 36 are the same as the thickness of the battery 20, and the substrates 30, 31 and the thermistor 35 are
Is not viewed from the thickness of the battery 20. Therefore, the inner dimension of the thickness of the main body case 10 is substantially the same as the thickness of the battery 20, and it is not necessary to further increase the thickness.

Reference numeral 40 denotes a first lead plate, and reference numeral 41 denotes a second lead plate. 42 is the electrode section 22 and the thermistor 3
5 is a lead plate for connecting the lead plate 5 to the lead plate 5. First lead plate 40
Are a first printed circuit board 30 and a second printed circuit board 31
And are connected. The second lead plate 41 connects the second printed circuit board 31 and the battery outer can 21. With these lead plates, the thermistor 35 and the first
And the second printed circuit board 31 is disposed along the side surface in the lateral direction of the battery 20. Then, the second lead plate 41 is further bent and connected to the outer can 21 on the side facing the first printed circuit board 30.

The lead plate 41 includes a thermistor 35,
It is electrically connected to the battery outer can 21 via the first printed board 30 and the second printed board 31. On the other hand, the lead plate 42 is electrically connected to the electrode portion 22 different from the outer can.

[0013]

However, when a lithium battery is used as a battery, the greatest advantages are high energy density and high voltage, so that it can be widely used in mobile phones and notebook computers. It is known that there is a problem with safety.

Particularly, charging and discharging are problematic, and the mechanical strength of the lead plate needs to be sufficiently high. Also, the lead plate 41,
41 was made of Ni because it was welded to the outer can 21 and the electrode cap 22 with a spot welder. However, Ni has poor wettability with solder, and it is difficult to control the amount of solder between the Ni lead and the pad electrode. Therefore, there is a problem that the peel strength of the bonding portion varies greatly and very weak ones are generated.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems. First, a slit serving as a flux escape portion when a lead plate and the pad electrode are soldered to the surface of the pad electrode is provided. This can be solved by providing.

Secondly, the lead plates are arranged on the pad electrodes provided with slits on the surface thereof at a large interval on a side of the mounting substrate and at a small interval at an end located on the mounting substrate. The problem is solved by being fixed by soldering.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below.

According to the present invention, as shown in FIG.
1, the electrode portion 22 is a negative electrode (or a positive electrode), and the outer can 21 is entirely a positive electrode (or a negative electrode). And on the surface of this outer can 21,
A mounting substrate such as a printed substrate 31, 31, a ceramic substrate, a metal substrate, or a flexible substrate is mounted, and a lead plate made of Ni extended from the mounting substrate is connected to the outer can 21 and the electrode portion 22 with the spot welder and the like. Welded.

Hereinafter, the mounted circuit board 51 to which the lead plate 50 is attached will be described with reference to FIG. First, the mounting circuit board 51 is preferably made of an insulating material itself such as a printed board, a ceramic board, and a flexible sheet. However, a metal substrate may be used as long as an insulating sheet is interposed between the outer can and the mounting substrate. In the case of a metal substrate, the effect is great if the mounting surface and the outer can face each other and the back surface is oriented so as to face the external atmosphere because the metal substrate itself shields external noise. Further, even if heat is generated in a circuit mounted thereon, the metal substrate functions as a heat radiating substrate or a heat sink, and is effective in preventing ignition.

As described above, a pattern 52 (wiring, solder pad, bonding pad, etc.) made of copper foil is formed on the mounting board 51, and an active element (here, a semiconductor element such as an IC or a discrete element) is formed thereon. ) 53 and passive elements (here, chip capacitors, chip resistors, etc.) 54 are electrically connected. These constitute a protection circuit that protects the battery from overcharge and overdischarge.

In the vicinity of the mounting circuit board 51, N
The i-lead plate 50 is connected to the pad electrode 55 via the solder 56.

A feature of the present invention is that a slit 57 is provided on the surface of the pad electrode 55 as a flux escape portion when the lead plate 50 and the pad electrode 55 are fixed by soldering.

Hereinafter, the reason for providing the slit 57 will be described. That is, the lead plate 50 needs to be bent as shown in FIG. 5 and needs peeling strength in the direction of arrow Y shown in FIG.

Here, the reason why the peeling strength is not stable is that the flux component does not come out of the pad electrode 55 when the solder is fixed, and there is a portion where the solder is not fixed and becomes a cavity.

Therefore, in the present invention, as described above, the slit 57 is provided on the surface of the pad electrode 55 so that the flux component easily comes out of the pad electrode 55 through the slit 57 when the solder is fixed, so that the solder is not fixed. The peeling strength is stabilized by minimizing the portion that becomes a cavity with.

FIGS. 2 and 3 are views showing an example of the slit 57. FIG. 2A shows a cross-shaped slit 57A provided on the surface of the pad electrode 55, and FIG. 2C, a slit 57C is provided so as to divide the surface of the pad electrode 55 into four parts, and FIG. 2D and FIG. Slits 57D and 57E are provided in the vertical and horizontal directions so as to divide the surface into two. Further, FIGS. 3B and 3C show a plurality of slits 57F parallel or oblique to the surface of the pad electrode 55. , 57G
Shows the state provided with.

The structure of the slit 57 of the present invention is not limited to these, but can be variously changed.
5 The surface may be half-etched to form a concave portion. If there is no possibility that the solder will penetrate to the back surface and cause insulation failure, the slit may be penetrated.

By adopting the above-described structure in which the slits serving as the flux release portions are provided, for example, the cleaning efficiency in the case of performing the flux cleaning can be improved.

Hereinafter, another embodiment of the present invention will be described.

A feature of another embodiment of the present invention is that the lead plate 50 is thicker on the side of the mounting board as shown in FIG. 4 on the pad electrode 55 provided with the slit 57 on the surface. At the end located on the mounting board, the solder is fixed so as to be arranged at a small interval.

Hereinafter, an experiment shown in FIG. 5 according to another embodiment of the present invention was performed.

The size of the pad electrode for soldering is 4 mm.
× 4 mm, the size of the lead plate is 4 mm × 40 mm,
The thickness was 0.15 mm. FIG. 5 shows a conventional type in which the lead plate and the pad electrode are parallel to each other without inclination.
The experiment was conducted with three types of a slope A type in which solder was fixed to the lower right as shown in the lower left of FIG. Here, the amount of solder is controlled by the number of solder shots, and is 2.9 mm per shot. The Ni lead has no pretreatment and the pull direction is 9
0 degree vertical direction, the pulling speed is 30 mm / min, and the measurement temperature is about 20 degrees.

In the table of FIG. 5, the peeling strength increases as the number of shots increases from the left to the four types without tilt. That is, as the amount of solder increases, the peeling strength increases. Also, the gradient B has a strength about twice that of the gradient A.

Further, a, b, c, d, and e after the numeral indicate a destruction mode, where a is between Ni and solder, b is solder, and c is between solder and pad electrode (land). Where d is between the pad and the glass epoxy substrate, and e indicates that the glass epoxy substrate is broken.

From the above experimental results, two things can be said.

As the amount of solder increases, the peeling strength increases.

When peeling, if the solder portion serving as a fulcrum is thick, the stress concentrated on the fulcrum will be dispersed.

By setting the slope B, the peeling strength can be increased.

Here, the portion corresponding to the end portion (short side B, C) of the mounting circuit board in FIG. 1, that is, the portion indicated by the arrow E in FIG. Do more.

From the above experimental results, it has been proved that the effect of increasing the peeling strength by making the solder in the portion indicated by arrow E in FIG. 4 larger than the solder amount in the portion indicated by arrow D in FIG.

Therefore, in another embodiment of the present invention, the lead plate 50 is thick on the side of the mounting board on the pad electrode 55 provided with the slit 57 described in one embodiment, By fixing the solder at the upper end portion so as to be arranged at a small interval, the state of the fixed solder can be stabilized.

As described above, solder is applied with solder cream or the like on the pad electrodes 55 arranged on the front or back of the mounted circuit board, the pad electrodes 55 of the mounted circuit board and the lead plate 50 are overlapped, and heat is applied to apply heat. Although pressure melting is performed, since the slit 57 is provided, the flux component easily comes out of the pad electrode 55 through the slit 57, and a material having a small variation in peeling strength can be realized.

The battery in which the thus-completed mounted circuit board is mounted on the outer can is mounted on the main body case as required, and the lid is fitted thereto, thereby forming a product.

[0044]

According to the present invention, firstly, by providing a slit on the surface of the pad electrode as a flux escape portion when the lead plate and the pad electrode are fixed by soldering, variation in peeling strength is reduced. Thus, the lead plate can be fixed in a stable state.

Second, the lead plate is solder-fixed so that it is thick on the side of the mounting substrate and thin at the end located on the mounting substrate, so that the lead plate can be arranged in a parallel manner. Can further improve the strength.

[Brief description of the drawings]

FIG. 1 is a view of a mounting board attached to a battery of the present invention.

FIG. 2 is a view showing a slit shape formed on a pad electrode surface of FIG. 1;

FIG. 3 is a view showing a slit shape formed on a pad electrode surface of FIG. 1;

FIG. 4 is a diagram illustrating the relationship between the mounting board and the lead plate of FIG. 1;

FIG. 5 is a diagram illustrating the results of a peeling test of a lead plate.

FIG. 6 is an assembly view of a conventional battery.

FIG. 7 is a diagram when a battery is mounted on a main body case.

[Explanation of symbols]

 Reference Signs List 50 Ni lead plate 51 Mounting substrate 52 Conductive pattern 53 Active element 54 Passive element 55 Pad electrode 56 Solder 57 Slit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E317 AA07 AA11 CC02 CC15 CD34 GG05 GG07 5E344 AA02 AA22 BB02 BB06 BB13 CC23 CD14 DD02 EE17 EE26 5H020 AA01 AS14 BB03 DD02 DD07 DD20 5H030 AA09 AA10 AS11

Claims (6)

[Claims] 1. A mounting having a pad electrode provided on the surface of a mounting substrate (or the back surface of a mounting substrate) on which circuit elements are mounted and capable of being fixed by solder, and a lead plate connected to the pad electrode via solder. A circuit board, wherein a slit is provided on a surface of the pad electrode. 2. A mounting having a pad electrode provided on the front surface (or the back surface) of a mounting substrate on which a circuit element is mounted and capable of being fixed by solder, and a lead plate connected to the pad electrode via solder. In the circuit board, the lead plates are arranged on the pad electrodes provided with slits on the surface thereof, so that the lead plates are thick on the side of the mounting substrate and thin at the end located on the mounting substrate. A mounting circuit board, which is fixed by soldering. 3. The mounting circuit board according to claim 1, wherein the slit serves as a flux release portion when the lead plate and the pad electrode are fixed by soldering. 4. A protruding electrode portion having a polarity; a rectangular outer can that serves as an electrode having a different polarity from the electrode portion; and a battery circuit disposed on the surface of the outer can, wherein the circuit for the battery is formed on the surface. A battery comprising: a mounted mounting substrate; a pad electrode provided around the front surface of the mounting substrate (or the back surface of the mounting substrate); and a lead plate connected to the pad electrode via solder. A battery, wherein a slit is provided on a surface of the pad electrode. 5. A protruding electrode portion having a polarity; a rectangular outer can which is an electrode having a different polarity from the electrode portion; and a battery circuit disposed on the surface of the outer can, wherein the circuit for the battery is formed on the surface. A battery comprising: a mounted mounting substrate; a pad electrode provided around the front surface of the mounting substrate (or the back surface of the mounting substrate); and a lead plate connected to the pad electrode via solder. The lead plate was solder-fixed on the pad electrode provided with a slit on its surface such that the lead plate was thick on a side of the mounting substrate and thin at an end located on the mounting substrate. A battery comprising: 6. The battery according to claim 4, wherein the slit serves as a flux release portion when the lead plate and the pad electrode are fixed by soldering.