Patent Description:
A junction box for a solar power generation assembly is an important component installed in a solar power generation assembly. It plays a role in providing bypass protection for cells in the assembly and transmitting out power generated by the assembly. A solar power system connects a number of power generation assemblies in series and/or parallel via output cables in the junction boxes of the assemblies as well as connectors to realize power generation in high power, and provide power for users or connects the grid to supply power through power accumulation or inversion.

Principle of bypass protection of cells provided by junction box: The solar power generation assemblies in a solar power station system generate power under normal irradiation of sunlight and output electric energy, but when the sunlight irradiating a location of a power generation assembly is blocked by an object or a shadow of an object, the state of the silicon cell at this location will be changed from a power generation state into a resistance state. Other power generation assemblies connected to the silicon cell in series generate power normally under irradiation of sunlight and current passing the cell in a resistance state will generate large heat, burning down the cell and backing sheet of the assembly. This phenomenon is called hot spots of assemblies. In order to prevent hot spots, a bypass diode is reversely connected in parallel with each silicon cell pack in solar power generation assemblies. When conditions for hot spots appear, the diode is connected in a normal direction and current is output via the bypass diode, thereby protecting the silicon cells from burn-down and the safety of the power generation assembly.

Bypass diodes are designed to be installed inside a junction box. Currently, three bypass diodes are typically installed in a common junction box, and each of them provides bypass protection for one third of the cells in the solar power generation assembly. Therefore, junction boxes for solar power generation assemblies simultaneously have functions of bypass protection and power output.

Over the years, junction boxes have undergone multiple improvements and developments. For example, junction boxes are known from <CIT> and <CIT>.

A junction box made in the prior art typically comprises an individual diode packaging device, a junction box body (box body and box cover), internal copper conducting heat sinks (copper conductors), output cables and connectors. Diodes are assembled by means of buckling or surface-mounted diodes are used, which are assembled by means of reflow soldering to copper conducting heat sinks inside the junction box; and the copper conducting heat sinks assembled with the diodes are installed inside the junction box body by means of hot riveting of plastics. Therefore, the manufacturing and installation processes of the junction box have many steps and are labor consuming.

There is a high access threshold to manufacturing and sale of junction boxes. Currently, IEC-<NUM> standard is executed. Junction boxes produced in the prior art meet with difficulty in solving problems about sealing performance, temperature rise and internal gas expansion.

In the current market, there are many photovoltaic module products packaged with a plurality of diode chips.

The solution is to integrate three diode chips into an injection molding body. It can simplify the process steps of diode soldering and assembly of the junction box manufacturer. However, in terms of structure and application requirements, the module is fixed inside a junction box still by mounting method, sealant still needs to be filled in the inner chamber of the box body after the solar power assembly manufacturer installs the junction box into a power generation assembly, and the product does not have obvious advantages in production and application.

Due to the impact of structure and process on the photovoltaic module, a large packaging volume and different materials, materials will be expanded in case of changes of temperature, generating a stress on the chips and affecting the service life of the product to some extent.

The photovoltaic bypass diode module is fixed and connected to the junction box body via a plastic tray in a buckled manner. As a result, the limited heat dissipation space inside the junction box cannot be effectively utilized, thus limiting the passing capacity of working current. Complex production equipment is required in the production and application of junction boxes to achieve automatic assembly.

Photovoltaic module products have the following defects in actual production and application:.

To address the foregoing problems, the present invention provides a low-pressure chip packaging type junction box for a solar power generation assembly and a processing method thereof, which can solve problems of large stress, high local temperature and uneven heat dissipation of the photovoltaic module, a low utilization rate of the internal heat dissipation space of the junction box and large investment in product development, integrate techniques relating to development and manufacturing of junction boxes with semiconductor packaging techniques to effectively enhance product performance and meanwhile reduce product cost and development cost and increase a degree of product automation.

A technical solution of the present invention: The low-pressure chip packaging type junction box for a solar power generation assembly comprises a box body, N chips, N connection members, and N+<NUM> copper conductors, where N≥<NUM>,.

When N><NUM>, a process connection ring is arranged between at least two copper conductors.

When N><NUM>, connection positions connecting the output end are further arranged on the first and the last copper conductors.

When N><NUM>, the chips are arranged on two sides of the transverse bar respectively.

Busbar guide holes are arranged on the transverse bar and run through the transverse bar from a back face of the box body; the lower openings of the busbar guide holes are large and the upper openings are small;.

Threading holes corresponding to the busbar through holes are arranged on the lead-out positions of the copper conductors.

The processing method of a low-pressure chip packaging type junction box for a solar power generation assembly comprises the following steps:.

The process connecting structure at step <NUM>) is a process connecting strip, which is located on a transverse bar,.

At step <NUM>), process connecting strips between adjacent copper conductors are cut off by blanking machine.

The process connecting structure at step <NUM>) is a process connection ring;.

A heat sink is further comprised, which is packaged inside epoxy resin adhesive.

The present invention designs the box body of the junction box into a plastic body having one or more adhesive storage slot with an opening top (i.e., accommodation recess); and determines the number of accommodation recesses according to the requirements of the junction box model and the requirements of heat dissipation distribution. For a box body having two or more accommodation recesses, the accommodation recesses are arranged in two lines, a transverse bar is arranged between two lines of accommodation recesses, busbar guide holes are arranged on the transverse bar, and threading holes are arranged on lead-out positions of copper conductors so as to place a busbar according to user's application. This distribution mode enables dispersion of heat sources during work of diodes, makes full use of the limited heat dissipation space in the junction box and reduces mutual impact.

In the present invention, chip installation positions are arranged on copper conductors and lead-out positions are arranged at a top surface of a transverse bar so that local copper conductors carrying diode chips by means of soldering sink through bending to enable the chips and partial copper conductors to be inlaid in corresponding accommodation recesses. Then epoxy resin adhesive with high thermal conductivity and high mechanical strength is potted into the accommodation recesses. After curing, the diode chips are sealed for protection, and the copper conductors are also fixed to the junction box body to form a junction box;.

N+<NUM> copper conductors are connected in series by means of the chips and the connection members. In order to eliminate a pull stress on the chips resulting from relative movement of the copper conductors in the manufacturing process, the present invention designs process connection rings or process connecting strips among copper conductors during punching of the copper conductors so that a plurality of copper conductors temporarily forms an integral body. After chip soldering, potting and curing, the process connection rings or process connecting strips are removed by means of drilling or punching.

The present invention steps over a packaging and manufacturing process of individually packaged diode junction boxes and photovoltaic module junction boxes, and skips work content such as secondary soldering and secondary assembly. The present invention integrates design and manufacturing of junction boxes with semiconductor diode packaging techniques and avoids potential quality hazard of junction box products arising from secondary soldering and installation; greatly raises development speed of junction boxes; saves the processes of mutual running-in and adjustment of the junction box manufacturer and the semiconductor diode packaging manufacturing; and facilitates a more compact structure of the junction box products, more reasonable use of materials, faster development of products, easier realization of automated production, lower product manufacturing cost and stronger market competitiveness.

In the <FIG> denotes a box body, <NUM> denotes an accommodation recess, <NUM> denotes a transverse bar, <NUM> denotes a busbar guide hole, <NUM> denotes a positioning stud, <NUM> denotes a conical blind hole, <NUM> denotes a chip, <NUM> denotes a connection member, <NUM> denotes a copper conductor, <NUM> denotes an installation hole, <NUM> denotes a lead-out position, <NUM> denotes a threading hole, <NUM> denotes a connection position, <NUM> denotes a potting adhesive, <NUM> denotes a process connecting strip, <NUM> denotes a process connection ring, <NUM> denotes a heat sink, <NUM> denotes a copper conductor frame, and <NUM> denotes an ultrasonic bonding tool.

The present invention, as shown in <FIG>, comprises a box body <NUM>, N chips <NUM>, N connection members <NUM> and N+<NUM> copper conductors <NUM>, with N≥<NUM>. At least one accommodation recess <NUM> is arranged at the box body, and a transverse bar <NUM> with a top surface higher than a bottom of the accommodation recess is arranged on the box body;.

Sinking copper conductors are made of red copper, brass or alloy copper through punching and bending. The lower plane after bending is a sinking location. Each copper conductor has one or more sinking location; the sinking locations are distributed on one side or a few sides or at a middle position of the copper conductor.

As shown in <FIG> and <FIG>, when there is only one chip, chip installation positions are arranged on one of the two copper conductors, and lead-out positions are arranged on both of the copper conductors;.

When N=<NUM>, one node is formed; or when N><NUM>, N+<NUM> nodes are formed;
The installation positions at the copper conductors, the chips and the connection members are potted, fixed and packaged within the accommodation recess by means of a potting adhesive <NUM>, and the lead-out positions of the copper conductors are located above the transverse bar and higher than a top surface of the potting adhesive.

A process connecting strip <NUM> is arranged between adjacent copper conductors so that a plurality of copper conductors temporarily forms an integral body to eliminate a pull stress on the chips resulting from relative movement of the copper conductors in the manufacturing process.

When N><NUM>, a process connection ring <NUM> is arranged between at least two copper conductors so that a plurality of copper conductors temporarily forms an integral body to eliminate a pull stress on the chips resulting from relative movement of the copper conductors in the manufacturing process.

When N><NUM>, connection positions connecting the output end are further arranged on the first and the last copper conductors. When N=<NUM>, a connection position connecting the output end is arranged on one copper conductor; and typically, when there is only one chip, a combined use is needed.

A clearance is arranged between copper conductors, which are electrically connected by means of chips and connection members, wherein the first copper conductor has an anode cable lead-out end and the last copper conductor has a cathode cable lead-out end, and the anode cable lead-out end and the cathode cable lead-out end are both arranged outside the box body;.

Busbar guide holes <NUM> are arranged on the transverse bar <NUM> and run through the transverse bar from a back face of the box body; and the lower openings of the busbar guide holes are large and the upper openings are small to play a guiding role and facilitate placement of a busbar;
Threading holes <NUM> corresponding to the busbar guide holes are arranged on the lead-out positions <NUM> of the copper conductors.

Threading holes and solder pads for customer's installation and soldering of a busbar are arranged on upper-layer stepped planes (i.e. lead-out positions) of sinking copper conductors; for copper conductors with one sinking location, threading holes and solder pads for customer's installation and soldering of a busbar are arranged on one side of the copper conductors; for copper conductors with two or more sinking locations, threading holes and solder pads for customer's installation and soldering of a busbar are arranged in the middle of the copper conductors.

The process connecting structure at step <NUM>) is a process connecting strip, which is located on a transverse bar and connected between lead-out positions of adjacent conductors,.

The present invention reserves a space on the transverse bar of the box body to punch and remove connecting strips after curing of epoxy resin in the accommodation recess.

The present invention arranges positioning studs matched with process connection rings of copper conductors inside accommodation recesses of the box body, and arranges conical blind holes corresponding to the positioning studs on a back face of the box body to play a guiding role to accurately remove the process connection rings by means of drilling.

Claim 1:
A low-pressure chip packaging type junction box for a solar power generation assembly, comprising a box body (<NUM>), N chips (<NUM>), N connection members (<NUM>) and N+<NUM> copper conductors (<NUM>), with N≥<NUM>, wherein,
at least one accommodation recess (<NUM>) is arranged at the box body (<NUM>), and a transverse bar (<NUM>) with a top surface higher than a bottom of the accommodation recess (<NUM>) is arranged on the box body (<NUM>);
N of the N+<NUM> copper conductors (<NUM>) correspond to the N chips (<NUM>) one to one, chip installation positions are arranged at N copper conductors (<NUM>), and the N+<NUM> copper conductors (<NUM>) are provided with lead-out positions positioned at a top surface of the transverse bar (<NUM>);
chips (<NUM>) are soldered and fixed to the installation positions at the copper conductors (<NUM>) and are connected to connection positions of adjacent copper conductors (<NUM>) via connection members (<NUM>);
the N+<NUM> copper conductors (<NUM>) are connected in series by means of the chips (<NUM>) and the connection members (<NUM>) and form a bypass circuit with an output end;
the installation positions at the copper conductors (<NUM>), the chips (<NUM>) and the connection members (<NUM>) are potted, fixed and packaged within the accommodation recess (<NUM>) by means of a potting adhesive, and the lead-out positions of the copper conductors (<NUM>) are located above the transverse bar (<NUM>) and higher than a top surface of the potting adhesive.