Detailed Description
In order to explain technical contents, achieved objects, and effects of the present invention in detail, the following description is made with reference to the accompanying drawings in combination with the embodiments.
Referring to fig. 2, the SMT mounting process for the LED display screen module of the present invention includes the following steps:
s1, printing an LED surface on one surface of a PCB by using solder paste, then installing an LED element, and connecting the LED element with the LED surface through reflow soldering;
and S2, printing a driving surface on the other surface of the PCB by using solder paste, then installing the electronic component, and connecting the electronic component with the driving surface by reflow soldering.
From the above description, the beneficial effects of the present invention are: the SMT mounting process of the LED display screen module breaks through the traditional process of mounting a driving surface first and then mounting the LED surface, mounting of the LED surface is carried out first and then mounting of the driving surface is carried out, tin paste can be accurately printed at a specified position through printing only according to the opening of a steel mesh related to the LED surface in the mounting process, shrinkage parameters of an LED bonding pad do not need to be measured first as in the traditional process, then an average value is obtained through calculation according to the shrinkage value and then the steel mesh is manufactured, and therefore the printing precision and the reflow soldering quality of the LED surface can be effectively guaranteed, the LED element can be accurately mounted at the specified position through a mounting machine, the problems of mounting offset, flying parts and the like can be avoided, the soldering quality is guaranteed, and the problems of poor soldering such as insufficient soldering, false soldering, offset, poor strength and the like caused by insufficient printing precision and improper mounting of the LED surface are avoided; the assembly precision of the LED display screen module and the mask can be effectively ensured, the LED element is positioned in the middle position, and the problems that the light source is shielded and the LED element falls off due to pressurization are avoided; the whole good display effect of display screen can be guaranteed, and the problems of wavy stripes and uneven brightness in the display process are avoided.
The LED display screen module is prepared by the SMT mounting technology of the LED display screen module.
The LED display screen is assembled by a plurality of LED boxes and is formed, the LED boxes comprise a plurality of display modules, and each display module comprises a face cover, a bottom shell and the LED display screen module arranged between the face cover and the bottom shell.
Further, the SMT mounting process specifically includes the following steps:
s1, printing an LED surface on one surface of a PCB by using solder paste, carrying out SIP inspection, mounting an LED element after the inspection is qualified, connecting the LED element with the LED surface by reflow soldering, and carrying out AOI inspection;
and S2, printing a driving surface on the other surface of the PCB by using solder paste, performing SIP inspection, mounting the electronic component after the inspection is qualified, connecting the electronic component with the driving surface by reflow soldering, performing AOI inspection, and lighting the LED module for detection after the inspection is qualified.
Furthermore, the melting point of the solder paste in the S1 is 100-180 ℃.
Further, when the melting points of the solder pastes used in the S1 and the S2 are different, when the reflow soldering of the S2 is carried out, the LED surface is provided with a jig which is used for preventing the LED element from falling off.
Further, the jig comprises a bottom plate, wherein a plurality of LED limiting grooves which are parallel to each other and are arranged at equal intervals are formed in the bottom plate, and the LED limiting grooves are used for accommodating LED elements.
Furthermore, a plurality of lock catches are arranged on the bottom plate, the lock catches are arranged on the periphery of the LED limiting groove, and the lock catches are used for connecting the bottom plate with the PCB.
Example 1:
referring to fig. 2, the SMT mounting process of the led display screen module includes the following steps:
s1, printing an LED surface on one surface of a PCB by using solder paste, carrying out SIP inspection, mounting an LED element 31 after the inspection is qualified, connecting the LED element 31 with the LED surface by reflow soldering, and carrying out AOI inspection;
s2, printing a driving surface on the other surface of the PCB by using solder paste, carrying out SIP inspection, mounting an electronic component after the inspection is qualified, connecting the electronic component with the driving surface by reflow soldering, carrying out AOI inspection, and lighting the LED module for detection after the inspection is qualified;
wherein the solder pastes used in S1 and S2 are medium-temperature solder pastes with a melting point of 151 ℃.
The real object diagram of the LED surface printed in the step S1 is shown in FIG. 3, and it can be seen that the solder paste is accurately printed on the PCB.
Example 2:
referring to fig. 4-6, the LED display screen is assembled by an LED box body, the LED box body includes a plurality of display modules, and the display modules include a face mask 1, a bottom case 2, and an LED display screen module 3 of embodiment 1 disposed therebetween.
The LED display screen of the embodiment 2 is lightened, the real object image after lightening is shown in figures 7-8, and figures 7 and 8 show the same LED display screen, one is in left view and the other is in right view.
Example 3:
referring to fig. 2, the SMT mounting process of the led display screen module includes the following steps:
s1, printing an LED surface on one surface of a PCB by using solder paste, performing SIP inspection, mounting an LED element 31 after the inspection is qualified, connecting the LED element 31 with the LED surface by reflow soldering, and performing AOI inspection;
s2, printing a driving surface on the other surface of the PCB by using solder paste, carrying out SIP inspection, mounting an electronic component after the inspection is qualified, connecting the electronic component with the driving surface by reflow soldering, carrying out AOI inspection, and lighting the LED module for detection after the inspection is qualified;
wherein the solder pastes used in S1 and S2 are low-temperature solder pastes with a melting point of 100-139 ℃.
Example 4:
referring to fig. 2, the SMT mounting process of the led display screen module includes the following steps:
s1, printing an LED surface on one surface of a PCB by using solder paste, carrying out SIP inspection, mounting an LED element 31 after the inspection is qualified, connecting the LED element 31 with the LED surface by reflow soldering, and carrying out AOI inspection;
s2, printing a driving surface on the other surface of the PCB by using solder paste, carrying out SIP inspection, mounting an electronic component after the inspection is qualified, connecting the electronic component with the driving surface by reflow soldering, carrying out AOI inspection, and lighting the LED module for detection after the inspection is qualified;
wherein the solder paste used in S1 is medium-temperature solder paste with a melting point of 140-180 ℃, and the solder paste used in S2 is high-temperature solder paste with a melting point of 200-230 ℃;
when performing reflow soldering in S2, the LED surface is provided with a jig for preventing the LED element 31 from falling off, referring to fig. 9-12, the jig includes a bottom plate 4, and the bottom plate 4 is provided with a plurality of LED limiting grooves 5 arranged in parallel and at equal intervals, and a plurality of latches 6; the LED limiting groove 5 is used for accommodating the LED element 31, the lock catch 6 is arranged on the periphery of the LED limiting groove 5, and the lock catch 6 is used for connecting the bottom plate 4 with the PCB.
Example 5:
referring to fig. 2, the SMT mounting process of the led display screen module includes the following steps:
s1, printing an LED surface on one surface of a PCB by using solder paste, carrying out SIP inspection, mounting an LED element 31 after the inspection is qualified, connecting the LED element 31 with the LED surface by reflow soldering, and carrying out AOI inspection;
s2, printing a driving surface on the other surface of the PCB by using solder paste, carrying out SIP inspection, mounting an electronic component after the inspection is qualified, connecting the electronic component with the driving surface by reflow soldering, carrying out AOI inspection, and lighting the LED module for detection after the inspection is qualified;
wherein the solder paste used in S1 is medium-temperature solder paste with a melting point of 100-138 ℃, and the solder paste used in S2 is medium-temperature solder paste with a melting point of 140-180 ℃;
when reflow soldering of the S2 is carried out, a jig is arranged on the LED surface and used for preventing the LED element 31 from falling off, the jig comprises a bottom plate 4, and a plurality of LED limiting grooves 5 which are parallel to each other and are arranged at equal intervals and a plurality of lock catches 6 are arranged on the bottom plate 4; the LED limiting groove 5 is used for accommodating the LED element 31, the lock catch 6 is arranged on the periphery of the LED limiting groove 5, and the lock catch 6 is used for connecting the bottom plate 4 with the PCB.
Example 6:
referring to fig. 2, the SMT mounting process of the led display screen module includes the following steps:
s1, printing an LED surface on one surface of a PCB by using solder paste, performing SIP inspection, mounting an LED element 31 after the inspection is qualified, connecting the LED element 31 with the LED surface by reflow soldering, and performing AOI inspection;
s2, printing a driving surface on the other surface of the PCB by using solder paste, carrying out SIP inspection, mounting an electronic component after the inspection is qualified, connecting the electronic component with the driving surface by reflow soldering, carrying out AOI inspection, and lighting the LED module for detection after the inspection is qualified;
wherein the solder paste used in S1 is low-temperature solder paste with a melting point of 100-138 ℃, and the solder paste used in S2 is high-temperature solder paste with a melting point of 200-230 ℃;
when reflow soldering of the S2 is carried out, a jig is arranged on the LED surface and used for preventing the LED element 31 from falling off, the jig comprises a bottom plate 4, and a plurality of LED limiting grooves 5 which are parallel to each other and are arranged at equal intervals and a plurality of lock catches 6 are arranged on the bottom plate 4; the LED limiting groove 5 is used for accommodating the LED element 31, the lock catch 6 is arranged on the periphery of the LED limiting groove 5, and the lock catch 6 is used for connecting the bottom plate 4 with the PCB.
Comparative example 1:
referring to fig. 1, the SMT mounting process of the led display screen module includes the following steps:
s1, printing a driving surface on one surface of a PCB by using solder paste, carrying out SIP inspection, mounting an electronic component after the inspection is qualified, connecting the electronic component with the driving surface by reflow soldering, carrying out AOI inspection,
s2, printing an LED surface on the other surface of the PCB by using solder paste, carrying out SIP inspection, mounting an LED element after the inspection is qualified, connecting the LED element with the LED surface by reflow soldering, carrying out AOI inspection, and lighting the LED module for detection after the inspection is qualified;
wherein the solder pastes used in S1 and S2 are medium-temperature solder pastes with a melting point of 151 ℃.
The real object diagram of the LED surface printed in step S2 is shown in fig. 13, the obtained LED display screen module is shown in fig. 14,
it can be seen that, in the upper right position of fig. 13, the solder paste is not printed on the designated position, the test is performed during the preparation process, and the PCB boards before and after production shrink 0.108mm inward and shrink 0.033mm downward, so that the printing is shifted, and the solder paste cannot be accurately printed on the designated LED pads.
It can be seen that a problem of poor soldering strength leading to peeling of the LED element occurs in fig. 14.
Comparative example 2:
the LED display screen is assembled by the LED box body to form, the LED box body includes a plurality of display modules, display module includes face guard, drain pan and sets up the LED display screen module of comparative example 1 between the two.
The LED display screen of example 2 is lit, and the actual image after lighting is shown in fig. 15, which shows that there are obvious dark and bright areas.
In summary, the SMT mounting process of the LED display module provided by the present invention breaks through the conventional process of mounting the driving surface first and then mounting the LED surface, and mounting the LED surface first and then mounting the driving surface, and is suitable for mounting when the LED display screen has a small distance and a high requirement for display effect; the SMT mounting technology is provided and used, and the problems that due to shrinkage of a PCB due to passing through a furnace, the printing precision is insufficient, and solder paste cannot be accurately printed on an appointed LED bonding pad are solved; the problems of welding strength of the LED component and welding flatness of the LED surface are solved; the problem that the LED component is not centered when the LED component is connected with the face mask is solved; the problems of poor display effect, wavy stripes and uneven brightness of the whole display screen are solved.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent changes made by using the contents of the present specification and the drawings, or applied directly or indirectly to the related technical fields, are included in the scope of the present invention.