Patent Description:
A protection circuit module (PCM) is connected to the battery cell to prevent overcharging and overdischarging, or preventing overcurrent from flowing. The PCM continuously detects voltage, current, temperature, etc. of the battery cell, and determines the state of the battery cell using the detected values. And, when overcharge, overdischarge, overcurrent, etc. are detected and it is determined that the battery cell is in an abnormal state, the PCM controls the operation of the battery cell. That is, the PCM stops charging or discharging of the battery cell, or blocks the electrical path.

In connecting the PCM and the battery cell, a bonding method using a laser is used. That is, after disposing the PCM on the lower side of the positive lead part and the negative lead part connected to the battery cell, the laser is irradiated from the upper side. Then, the positive and negative lead parts are welded and joined to the upper part of the PCM by heat by the laser.

Meanwhile, the PCM includes a copper foil connected to or bonded to positive and negative lead parts, a plurality of prepreg layers and a plurality of copper layers stacked on the lower side of the copper foil. In this case, the prepreg layer and the copper layer are alternately stacked.

However, the prepreg layer has a high transmittance with respect to the laser. Accordingly, when a laser is irradiated for bonding, the laser passes through the prepreg layer located below the copper foil, and then is incident on another layer laminated thereunder. Accordingly, when a laser is irradiated for bonding, the laser passes through the prepreg layer located below the copper foil, and then is incident on another layer laminated thereunder.

<CIT> discloses a battery pack including a protection circuit module.

The present invention provides a protection circuit module and a method of bonding a lead part and a protection circuit module capable of preventing the laser irradiated from the upper side from being transmitted to the lower side of the insulating layer.

According to an embodiment of the present invention, a protection circuit module is provided with a printed circuit board connected to a positive lead part and a negative lead part connected to a battery cell, wherein the printed circuit board includes: an upper layer bonded to the anode lead part and the cathode lead part so as to be electrically connected; an intermediate layer including a first insulating layer made of a material containing an epoxy resin and provided below the upper layer; and a laser reflective layer provided between the upper layer and the first insulating layer and reflecting a laser.

The laser reflective layer has a reflectance of <NUM>% or more of a laser having a wavelength of <NUM> to <NUM>.

The laser reflective layer may have a reflectance of <NUM>% or more of a laser having a wavelength of <NUM> to <NUM>.

The laser reflective layer is made of silver (Ag).

The laser reflective layer may be thinner than the upper layer and the intermediate layer.

The upper layer may be made of copper (Cu), wherein the first insulating layer may be made of a material including the epoxy resin and glass fiber.

The intermediate layer includes: second and third insulating layers provided below the first insulating layer; a first metal layer provided between the first insulating layer and the second insulating layer; and a second metal layer provided between the second insulating layer and the third insulating layer.

The second and third insulating layers may be made of a material including an epoxy resin and glass fiber, wherein the first and second metal layers may be made of copper (Cu).

According to an embodiment of the present invention, a bonding method of a lead part and a protection circuit module includes: preparing a printed circuit board including a laser reflective layer of a laser having a wavelength of <NUM> to <NUM> and having a reflectivity of <NUM>% or more; preparing a protection circuit module by mounting a protection circuit element on the printed circuit board; locating the protection circuit module below the lead part connected to an electrode of the battery cell; and bonding the lead part and the printed circuit board by irradiating a laser from an upper side of the lead part.

The preparing of the printed circuit board may include: preparing an upper layer using copper (Cu); preparing a first insulating layer using a material including an epoxy resin; and preparing the laser reflective layer between the upper layer and the first insulating layer.

The preparing of the printed circuit board includes: preparing second and third insulating layers under the first insulating layer; preparing a first metal layer between the first insulating layer and the second insulating layer; and preparing a second metal layer between the second insulating layer and the third insulating layer,.

The preparing of the laser reflective layer includes preparing using silver (Ag).

According to an embodiment of the present invention, it is possible to suppress or prevent the laser irradiated for bonding the lead part and the protection circuit module from being incident to the intermediate layer of the protection circuit module. Therefore, it is possible to prevent the intermediate layer of the protection circuit module from being damaged by the laser, thereby preventing damage to the protection circuit module by the laser.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and these embodiments are provided to complete the disclosure of the present invention, and to fully inform a person of ordinary skill in the scope of the invention. The drawings may be exaggerated in order to explain the embodiment of the present invention, and like reference numerals in the drawings refer to the same components.

<FIG> is a diagram illustrating a battery pack including a protection circuit module according to an embodiment of the present invention. <FIG> is a diagram conceptually illustrating a state in which a laser is irradiated from the upper side of the lead part in order to connect the lead part and the printed circuit board of the protection circuit module. <FIG> is a diagram illustrating a configuration of a printed circuit board according to an embodiment of the present invention and a state in which a laser is irradiated from an upper side of a lead part in order to connect the printed circuit board and the lead part.

Here, <FIG> and <FIG> are diagrams illustrating a state in which a laser is irradiated from the upper side of the lead part in order to connect the positive lead part and the printed circuit board among the lead parts.

Referring to <FIG>, a battery pack <NUM> according to an embodiment of the present invention includes a case <NUM> having an inner space, a battery cell <NUM> accommodated inside the case <NUM> and charging and discharging electricity, a lead part <NUM> including a positive lead part 1300a and a negative lead part 1300b connected to the battery cell <NUM>, and a protection circuit module <NUM> connected to the positive and negative lead parts 1300a and 1300b.

The case <NUM> includes an internal space that can accommodate the battery cell <NUM>, positive and negative lead parts 1300a and 1300b, and a protection circuit module <NUM>. The shape of the case <NUM> is not particularly limited, and any shape may be provided as long as it has an internal space that can accommodate the battery cell <NUM>, the positive and negative lead parts 1300a and 1300b, and the protection circuit module <NUM>.

The battery cell <NUM> is a means for charging and discharging current, and is a secondary battery. Such a battery cell may be a means including a positive electrode, a negative electrode, an electrolyte, and a separator positioned between the positive electrode and the negative electrode.

The lead part <NUM> is a means for electrically connecting the battery cell <NUM> and the protection circuit module <NUM>, and includes a positive lead part 1300a and a negative lead part 1300b. The positive lead part 1300a electrically connects the positive electrode of the battery cell <NUM> and the protection circuit module <NUM>, and the negative lead part 1300b electrically connects the negative electrode of the battery cell <NUM> and the protection circuit module. The positive and negative lead parts 1300a and 1300b may be made of, for example, nickel (Ni).

The protection circuit module <NUM> is a means commonly referred to as a protection circuit module (PCM). The protection circuit module <NUM> continuously detects the voltage, current, temperature, etc. of the battery cell <NUM>, and determines the state of the battery cell <NUM> using the detected value. And, when overcharge, overdischarge, overcurrent, etc. are detected and it is determined that the battery cell <NUM> is in an abnormal state, the protection circuit module <NUM> controls the operation of the battery cell <NUM>. For example, the protection circuit module <NUM> stops charging or discharging to the battery cell <NUM>, or blocks the electrical path. By the operation of the protection circuit module <NUM>, generation of heat and deterioration of the battery cell <NUM> due to overcharging and overdischarging can be prevented, and a fire can be prevented.

As shown in <FIG>, this protection circuit module <NUM> includes a printed circuit board (PCB) <NUM> connected to the positive and negative lead parts 1300a and 1300b and at least one protection circuit device <NUM> mounted on the printed circuit board <NUM>.

The protection circuit element <NUM> may be a passive or active element including a protection circuit, and may be mounted on or below the printed circuit board <NUM>. In addition, a plurality of protection circuit elements <NUM> may be provided. The protection circuit element <NUM> is provided to protect from the risk of ignition or explosion due to overcharge, overdischarge, heat due to overcurrent, and the like.

The printed circuit board <NUM> is electrically connected to the positive and negative lead parts 1300a and 1300b, and is connected by a welding method using a laser. When described in more detail with reference to <FIG>, after disposing the positive and negative lead parts 1300a and 1300b on the printed circuit board <NUM>, the laser L is irradiated from the upper side of the positive and negative lead parts 1300a and 1300b. In this case, as the laser L, a laser having a wavelength of <NUM> to <NUM>, more specifically <NUM> to <NUM>, and more specifically <NUM> is used. The positive and negative lead parts 1300a and 1300b are welded, i.e., bonded, to the upper portion of the printed circuit board <NUM> by the thermal energy of the laser L irradiated thereto.

Hereinafter, the printed circuit board <NUM> of the protection circuit module <NUM> according to the embodiment will be described with reference to <FIG>. In this case, the positive lead part 1300a and the negative lead part 1300b connected to the printed circuit board <NUM> are collectively referred to as a lead part <NUM> for convenience of description.

As shown in <FIG>, the printed circuit board <NUM> according to the embodiment includes an upper layer <NUM> and a lower layer <NUM> each made of metal and spaced apart vertically, an intermediate layer <NUM> provided between the upper layer <NUM> and the lower layer <NUM> and including an insulating layer that is light-transmitting, and a laser reflective layer <NUM> positioned between the upper layer <NUM> and the intermediate layer <NUM> to reflect light.

The upper layer <NUM> is electrically connected to, that is, bonded to, the lead parts <NUM>: 1300a and 1300b, and may be a layer constituting a circuit. The upper layer <NUM> is made of a metal having conductivity so as to be electrically connected to the lead part <NUM>. For example, the upper layer <NUM> may be made of copper (Cu), and thus the upper layer <NUM> made of copper (Cu) may be referred to as a copper foil layer. And a protection circuit element <NUM> may be mounted on the upper layer <NUM>, and accordingly, the protection circuit element <NUM> may be electrically connected to the battery cell <NUM> through a circuit, that is, the upper layer <NUM> and the lead part <NUM>. In addition, the thickness of the upper layer <NUM> may be provided to be <NUM> or more, and more specifically, may be provided to be <NUM> or more and <NUM> or less.

On the other hand, when the thickness of the upper layer <NUM> is less than <NUM>, the conductivity of the upper layer <NUM> is low, and electrical connection with the lead part <NUM> may be unstable. In addition, the thickness of the upper layer <NUM> is set to <NUM> or less because sufficient conductivity can be ensured with a thickness of <NUM> or less, and therefore, it is not necessary to make the thickness more than <NUM>.

The lower layer <NUM> is a layer provided under the intermediate layer <NUM>, and may be provided in the same manner as the above-described upper layer <NUM>, and may be a layer constituting a circuit. That is, the lower layer <NUM> may be a copper foil layer made of copper (Cu), and may be provided with a thickness of <NUM> or more, more specifically, a thickness of <NUM> or more and <NUM> or less.

The intermediate layer <NUM> includes a plurality of insulating layers and at least one metal layer. And the insulating layer and the metal layer are alternately or alternately disposed. At this time, an insulating layer is disposed on the top and bottom, and a metal layer is disposed therebetween. And, the insulating layer is provided with a material containing an epoxy resin. Accordingly, the insulating layer has a property that light, that is, a laser L for bonding the lead part <NUM> and the printed circuit board <NUM> to each other, is transmitted. More specifically, the insulating layer may transmit a laser L of a wavelength for bonding the lead part <NUM> and the printed circuit board <NUM> to each other. That is, the insulating layer may transmit a laser of <NUM> to <NUM>, more specifically, a laser of <NUM> more specifically than a <NUM> to <NUM> laser.

Hereinafter, the intermediate layer <NUM> will be described in more detail. Referring to <FIG>, the intermediate layer <NUM> includes the uppermost first insulating layer 1412a-<NUM>, and a first metal layer 1412b-<NUM>, a second insulating layer 1412a-<NUM>, a second metal layer 1412b-<NUM>, and a third insulating layer 1412a-<NUM> sequentially stacked from the first insulating layer 1412a-<NUM> to the upper portion of the lower layer <NUM>. Accordingly, the first metal layer 1412b-<NUM> is positioned between the first insulating layer 1412a-<NUM> and the second insulating layer 1412a-<NUM>, and the second metal layer 1412b-<NUM> is provided between the second insulating layer 1412a-<NUM> and the third insulating layer 1412a-<NUM>.

The first and third insulating layers 1412a-<NUM> and 1412a-<NUM> may be prepregs in which an epoxy resin is impregnated into a fiber reinforcement. In this case, the fiber reinforcement may be, for example, fiber glass. In addition, the second insulating layer 1412a-<NUM> may be a material in which epoxy resin-impregnated glass fibers are stacked in multiple layers, that is, FR-<NUM>.

The first and second metal layers 1412b-<NUM> and 1412b-<NUM> may be made of copper (Cu). In addition, the first and second metal layers 1412b-<NUM> and 1412b-<NUM> may have a thickness of <NUM> to <NUM>.

Meanwhile, the first to third insulating layers 1412a-<NUM>, 1412a-<NUM>, and 1412a-<NUM> are materials including an epoxy resin and glass fibers as described above, and these materials have high transmittance of the laser L. That is, the transmittance with respect to the wavelength range of <NUM> to <NUM> of the laser L irradiated for bonding the lead part <NUM> and the printed circuit board <NUM> is high.

Accordingly, when irradiating a <NUM> to <NUM> laser from the upper side of the lead part <NUM> for bonding, the laser L that has passed through the upper layer <NUM> may pass through the first insulating layer 1412a-<NUM>, and then may pass through the lower side thereof. In this case, the first insulating layer 1412a-<NUM> and the plurality of layers stacked thereunder, that is, the first metal layer 1412b-<NUM>, the second insulating layer 1412a-<NUM>, the second metal layer 1412b-<NUM>, and the third insulating layer 1412a-<NUM> may be damaged, and accordingly, the printed circuit board <NUM> may be damaged.

Accordingly, it is necessary to prevent the laser L irradiated to the printed circuit board <NUM> from being incident on the intermediate layer <NUM>. That is, it is necessary to prevent the laser L from being incident on the lower side of the first insulating layer 1412a - <NUM>. In other words, it is necessary to prevent the laser L from being incident or transmitted into the first insulating layer 1412a - <NUM>. More specifically, it is necessary to prevent the laser L from being transmitted below the upper surface of the first insulating layer 1412a-<NUM>.

Accordingly, in the embodiment, a laser reflective layer <NUM> capable of reflecting the laser L is provided between the upper layer <NUM> and the intermediate layer <NUM>. That is, a laser reflective layer <NUM> for reflecting the laser L is provided between the upper layer <NUM> and the first insulating layer 1412a-<NUM>.

The laser reflective layer <NUM> may be provided so that the reflectance of the laser L irradiated for bonding the lead part <NUM> and the printed circuit board <NUM> is <NUM>% or more. That is, the laser reflective layer <NUM> is provided so that the reflectance of the laser L of a wavelength of <NUM> to <NUM> is <NUM>% or more.

The laser reflective layer <NUM> is made of a material including a metal, and is made of silver (Ag). In addition, the thickness of the laser reflective layer <NUM> may be provided with any thickness as long as the reflectance can be <NUM>% or more. In this case, the thickness of the laser reflective layer <NUM> is preferably thinner than that of the upper layer <NUM>, the lower layer <NUM>, and the intermediate layer <NUM>.

Hereinafter, a method of bonding a lead part to a protection circuit module according to an embodiment of the present invention will be described with reference to <FIG>.

First, a protection circuit module <NUM> including a printed circuit board <NUM> according to the embodiment is prepared. That is, provided is a printed circuit module <NUM> including a printed circuit board <NUM> provided with a laser reflective layer <NUM> having a laser reflectance of <NUM>% or more between the upper layer <NUM> and the intermediate layer <NUM> as including an upper layer <NUM>, an intermediate layer <NUM>, and a lower layer <NUM>, and a protection circuit element <NUM> mounted on the printed circuit board <NUM>.

Then, as shown in <FIG>, the protection circuit module <NUM> is positioned below the lead part <NUM> connected to each of the positive and negative electrodes of the battery cell <NUM> , that is, the positive and negative lead parts 1300a and 1300b.

Thereafter, the laser L is irradiated from the upper side of the positive and negative lead parts 1300a and 1300b as shown in <FIG> and <FIG>. At this time, a laser L having a wavelength of <NUM> to <NUM>, more specifically, a wavelength of <NUM> to <NUM> is irradiated. As a more specific example, a laser L of <NUM> is irradiated.

Accordingly, the laser L is irradiated to the printed circuit board <NUM> of the lead part <NUM> and the protection circuit module <NUM>, and at least a portion of each of the lead part <NUM> and the printed circuit board <NUM> is melted and bonded to each other by the heat of the laser L. That is, at least a portion of the upper layer <NUM> and the lead part <NUM> of the printed circuit board <NUM> is melted and joined.

In this case, the laser L irradiated toward the lead part <NUM> and the printed circuit board <NUM> may pass through the lead part <NUM> and the upper layer <NUM> of the printed circuit board <NUM>. That is, the laser L may be incident into the lead part <NUM> and the upper layer <NUM>. However, the laser L that has passed through the upper layer <NUM> is reflected by the laser reflective layer <NUM> thereunder as shown in <FIG>. Accordingly, the laser L does not pass through the first insulating layer 1412a-<NUM> positioned under the laser reflective layer <NUM>, and thus does not enter the lower side of the first insulating layer 1412a-<NUM>.

More specifically, <NUM>% or more of the laser L that has passed through the upper layer <NUM> is reflected from the laser reflective layer <NUM> and goes out to the upper side of the upper layer <NUM> again. Accordingly, a very small amount of less than <NUM>% of the laser L that has passed through the upper layer <NUM> may be incident on the first insulating layer 1412a-<NUM> after passing through the laser reflective layer <NUM>.

As such, in the embodiment, it is possible to suppress or prevent the laser L irradiated for bonding from being incident to the intermediate layer <NUM>. That is, it is possible to suppress or prevent incident or transmission into the first insulating layer 1412a - <NUM>. Accordingly, it is possible to prevent the intermediate layer <NUM> provided under the upper layer <NUM> from being damaged by the laser L, and for this reason, damage to the printed circuit board <NUM> or the protection circuit module <NUM> by the laser L can be prevented.

Claim 1:
A protection circuit module (<NUM>) provided with a printed circuit board (<NUM>) connected to a positive lead part (1300a) and a negative lead part (1300b) connected to a secondary battery cell (<NUM>),
wherein the printed circuit board (<NUM>) comprises:
an upper layer (<NUM>) bonded to the anode lead part (1300a) and the cathode lead part (1300b) so as to be electrically connected;
an intermediate layer (<NUM>) including a first insulating layer (1412a-<NUM>) made of a material containing an epoxy resin and provided below the upper layer (<NUM>); and is characterised in that it further comprises
a laser reflective layer (<NUM>) provided between the upper layer (<NUM>) and the first insulating layer (1412a-<NUM>) and reflecting a laser;
wherein the laser reflective layer (<NUM>) has a reflectance of <NUM>% or more of a laser having a wavelength of <NUM> to <NUM>; and
wherein the laser reflective layer (<NUM>) is made of silver (Ag).