Packaging technology of rectifier bridge
Technical Field
The invention relates to the technical field of rectifier bridges, in particular to a packaging process of a rectifier bridge.
Background
The rectifier bridge is used as a power component, and the bridge circuit mainly comprising four diodes is used for converting input alternating voltage into output direct voltage, so that the rectifier bridge is widely applied to various power supply devices at present.
The current rectifier bridge mainly comprises an aluminum substrate, a plastic package body, a rectifier component and pins, and as disclosed in patent publication No. CN203631532U, the semiconductor rectifier bridge comprises the plastic package body, a frame for fixing a diode and an aluminum substrate, wherein the aluminum substrate is placed on the frame, the frame and the aluminum substrate are connected into a whole through the plastic package body, and the distance between the aluminum substrate and the frame is smaller than 1mm. The patent can effectively reduce the thermal resistance of the semiconductor rectifier bridge, improve the power density of the semiconductor rectifier bridge and have better performance. However, through practical use of the applicant, it is found that the gap between the aluminum substrate and the frame is smaller than 1mm, and epoxy resin fills the area during plastic packaging, so that the power-on capability and the heat conduction effect of the rectifier bridge are not optimal.
Disclosure of Invention
The invention aims to overcome the problems in the prior art and provides a packaging process of a rectifier bridge, wherein a single-sided aluminum-based copper-clad plate is adopted to replace an aluminum substrate in the process of preparing the rectifier bridge, a copper foil design circuit is utilized to directly weld the aluminum-based copper-clad plate and a chip, local copper particles are adopted to serve as the bearing between the chip and the aluminum-based copper-clad plate, and then a gap between the aluminum substrate and the chip is eliminated through solder paste welding, so that better power-on capability and heat dissipation effect can be ensured, and the technical problems of weaker power-on capability and poorer heat dissipation effect of the existing rectifier bridge are effectively solved.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
the packaging process of the rectifier bridge is characterized by comprising the following steps of:
step A: copper foil is thermally pressed on an aluminum substrate to form an aluminum-based copper-clad plate, and then the anode copper foil, the cathode copper foil, the first alternating current copper foil and the second alternating current copper foil which are mutually spaced are formed through corrosion;
and (B) step (B): respectively dispensing solder paste on the positive copper foil, and respectively dispensing solder paste on the first alternating current copper foil and the second alternating current copper foil;
step C: copper particles are respectively fixed on the positive copper foil, the first alternating current copper foil and the second alternating current copper foil through solder paste;
step D: dispensing solder paste on each copper particle again;
step E: the chip is respectively fixed on each copper particle through solder paste;
step F: presetting connection sheet fixing positions corresponding to the chips on the negative copper foil, the first alternating current copper foil and the second alternating current copper foil respectively, and dispensing solder paste on the connection sheet fixing positions and the chips;
step G: fixing connecting pieces between each chip and each connecting piece fixing position through solder paste to form a semi-finished rectifying frame, and then spot solder paste on the end parts of the positive copper foil, the negative copper foil, the first alternating current copper foil and the second alternating current copper foil;
step H: assembling the semi-finished rectifying frame and the lead frame together through the carrier and the end solder paste to form a semi-finished frame;
step I: all solder pastes on the semi-finished product frame are melted into alloy by adopting a high-temperature sintering process, so that welding work is completed;
step J: performing epoxy resin plastic package on the welded semi-finished frame by adopting a high-temperature hot-pressing injection molding process;
step K: plating tin on the surface of the semi-finished product frame after plastic packaging by adopting an electroplating process to obtain a complete rectifier bridge;
step L: dividing the rectifier bridge connected together into independent units by adopting a rib cutting process;
step M: and (3) carrying out parameter test on each rectifier bridge, packaging the rectifier bridges into a warehouse if the rectifier bridges are qualified, and repairing the rectifier bridges if the rectifier bridges are unqualified.
In the step C, copper particles on the positive copper foil are arranged symmetrically up and down, and copper particles on the first alternating current copper foil and copper particles on the second alternating current copper foil are arranged symmetrically up and down.
And C, the copper particles are of square structures, and the outer diameter of the copper particles is larger than or equal to the outer diameter of the chip.
The thickness of the copper particles in step C was 0.2mm.
The high-temperature sintering process in the step I adopts the temperature of 240-360 ℃ for sintering.
The high-temperature hot-pressing injection molding process in the step J adopts the temperature of 175+/-25 ℃ for hot-pressing injection molding.
The invention has the advantages that:
1. according to the invention, a single-sided aluminum-based copper-clad plate is adopted to replace an aluminum substrate in the process of preparing the rectifier bridge, the aluminum-based copper-clad plate and the chip are directly welded by utilizing a copper foil design circuit, local copper particles are adopted as the bearing between the chip and the aluminum-based copper-clad plate, and gaps between the aluminum substrate and the chip are eliminated by solder paste welding, so that better power-on capacity and heat dissipation effect can be ensured, and the rectifier bridge with better quality is obtained.
2. According to the invention, copper particles which are vertically symmetrical relative to a part are added in the process of preparing the rectifier bridge, and no gap exists between the aluminum-based copper-clad plate and the frame, so that better power-on capability and heat dissipation effect can be ensured, and the technical problems of weaker power-on capability and poorer heat dissipation effect of the traditional rectifier bridge are effectively solved.
3. The invention reduces the thermal resistance between the chip and the aluminum-based copper-clad plate and the consistency between products, and can specifically improve the power-on capability range of the products from 10-50A to 10-75A from 0.5-1.0 ℃/W to 0.4-0.5 ℃/W, thereby effectively improving the power-on capability and the heat dissipation effect of the products.
Drawings
FIG. 1 is a schematic diagram of the front view structure of step A;
FIG. 2 is a schematic bottom view of step A;
FIG. 3 is a schematic diagram of the front view structure of step B;
FIG. 4 is a schematic bottom view of step B;
FIG. 5 is a schematic diagram of the front view structure of step C;
FIG. 6 is a schematic bottom view of step C;
FIG. 7 is a schematic diagram of the front view structure of step D;
FIG. 8 is a schematic bottom view of step D;
FIG. 9 is a schematic diagram of the front view structure of step E;
FIG. 10 is a schematic bottom view of step E;
FIG. 11 is a schematic diagram showing the front view structure of step F;
FIG. 12 is a schematic bottom view of step F;
FIG. 13 is a schematic diagram showing the front view structure of step G;
FIG. 14 is a schematic bottom view of step G;
fig. 15 is a schematic diagram of the front view structure after solder paste is dispensed in step G;
FIG. 16 is a schematic bottom view of the solder paste in step G;
fig. 17 is a schematic structural diagram of step H.
Marked in the figure as: 1. the aluminum substrate comprises 2 parts of positive copper foil, 3 parts of first alternating current copper foil, 4 parts of second alternating current copper foil, 5 parts of negative copper foil, 6 parts of solder paste, 7 parts of copper particles, 8 parts of chips, 9 parts of connecting sheets, 10 parts of lead frames.
Detailed Description
Example 1
The invention provides a packaging process of a rectifier bridge, which comprises the following steps:
step A: as shown in fig. 1 and 2, an aluminum substrate 1 and a piece of copper foil are prepared, the piece of copper foil is thermally pressed on the aluminum substrate 1 to form an aluminum-based copper-clad plate, and then a positive copper foil 2, a negative copper foil 5, a first alternating copper foil 3 and a second alternating copper foil 4 which are mutually spaced are formed on the aluminum-based copper-clad plate through corrosion.
And (B) step (B): as shown in fig. 3 and 4, the solder paste 6 is dispensed on the upper and lower portions of the positive electrode copper foil 2, and one end of the first ac copper foil 3 near the negative electrode copper foil 5, and one end of the second ac copper foil 4 near the negative electrode copper foil 5 are dispensed with the solder paste 6.
Step C: as shown in fig. 5 and 6, four copper particles 7 are prepared, and the four copper particles 7 are fixed on the positive electrode copper foil 2, the first ac copper foil 3, and the second ac copper foil 4, respectively, by the solder paste 6. Since the solder paste 6 has viscosity, the preliminary fixation of the copper particles 7 can be achieved after the copper particles 7 are placed on the solder paste 6.
Preferably, the copper particles 7 on the positive copper foil 2 are arranged vertically symmetrically, and the copper particles 7 on the first alternating current copper foil 3 and the copper particles 7 on the second alternating current copper foil 4 are arranged vertically symmetrically. The copper particle 7 is square structure, and the thickness of copper particle 7 is 0.2mm, and the external diameter of copper particle 7 is greater than or equal to the external diameter of chip 8.
Step D: as shown in fig. 7 and 8, solder paste 6 is again dispensed onto each copper particle 7, and the solder paste 6 is used to connect the copper particle 7 and the chip 8.
Step E: as shown in fig. 9 and 10, four chips 8 are fixed to each copper particle 7 by solder paste 6.
Step F: as shown in fig. 11 and 12, the connection pad fixing positions corresponding to the chips 8 are preset on the negative copper foil 5, the first alternating current copper foil 3 and the second alternating current copper foil 4, and the solder paste 6 is dispensed on the connection pad fixing positions and the chips 8.
Step G: as shown in fig. 13 to 16, the connection pieces 9 are respectively fixed between the chips 8 and the connection piece fixing positions by solder paste 6 to form a semi-finished rectifying frame, and solder paste 6 is respectively dispensed at the end of the positive copper foil 2, the end of the negative copper foil 5, the end of the first alternating current copper foil 3 and the end of the second alternating current copper foil 4.
Since the number of the chips 8 is four and the number of the copper foils is four, the number of the connection pieces 9 is also four to better connect the respective components together.
Step H: as shown in fig. 17, the semi-finished rectifying frame and the lead frame 10 are assembled together by the carrier and the end solder paste 6 to constitute a semi-finished frame.
It should be noted that, in order to improve the production efficiency, the present step is to assemble a plurality of semi-finished rectifying frames with the lead frame 10, so as to complete the production of a plurality of rectifying bridges at one time.
Step I: all the solder paste 6 on the semi-finished frame is melted into alloy by adopting a high-temperature sintering process, and the welding work is completed.
The high-temperature sintering process in the step I adopts the temperature of 240-360 ℃ for sintering.
Step J: and (5) performing epoxy resin plastic package on the welded semi-finished frame by adopting a high-temperature hot-pressing injection molding process.
The high-temperature hot-pressing injection molding process in the step J adopts the temperature of 175+/-25 ℃ for hot-pressing injection molding.
Step K: and (3) adopting an electroplating process to tin-plate the surface of the semi-finished product frame after plastic packaging to obtain the complete rectifier bridge.
Step L: and the rectifier bridge connected together is divided into independent units by adopting a rib cutting process.
Step M: and (3) carrying out parameter test on each rectifier bridge, packaging the rectifier bridges into a warehouse if the rectifier bridges are qualified, and repairing the rectifier bridges if the rectifier bridges are unqualified.
In summary, the invention adopts the local copper particles 7 as the bearing between the chip 8 and the aluminum-based copper-clad plate, and eliminates the gap between the aluminum substrate 1 and the chip 8 by welding the solder paste 6, thereby ensuring better power-on capability and heat dissipation effect and further obtaining a rectifier bridge with better quality.
Example 2
In this embodiment, the rectifying bridge product obtained by the process of the present invention is tested for power-on capability and heat dissipation effect, and the semiconductor rectifying bridge disclosed in the patent document with publication number CN203631532U is used as a comparative example for equivalent test, and specific test results are as follows:
the test results show that the rectifier bridge obtained by the invention has better power-on capability and heat dissipation effect.
While the invention has been described with reference to certain embodiments, it is understood that any feature disclosed in this specification may be replaced by alternative features serving the equivalent or similar purpose, unless expressly stated otherwise; all of the features disclosed, or all of the steps in a method or process, except for mutually exclusive features and/or steps, may be combined in any manner.