CN211047449U - SMT template - Google Patents
SMT template Download PDFInfo
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- CN211047449U CN211047449U CN201921916837.5U CN201921916837U CN211047449U CN 211047449 U CN211047449 U CN 211047449U CN 201921916837 U CN201921916837 U CN 201921916837U CN 211047449 U CN211047449 U CN 211047449U
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Abstract
The novel SMT template comprises a frame, wherein a plate body is arranged on the inner side of the frame, soldering paste holes are formed in the plate body according to the size of an element pad, the thickness of the plate body is T < W/1.5 when the size of the pad is L > 5W, T < (L W)/[1.32 (L + W) ] when the pad is square or circular, coatings with the thickness of 20-30 nanometers are arranged on the surface of the plate body and the surface of the soldering paste holes, a product circuit board is cleaner and reliable through practice, the soldering paste holes are of special size, tin climbing of the product is better, records printed on a production line continuously for 13 ten thousand times are prevented from falling off through tests, the cost is saved, the frequency of steel mesh cleaning is reduced, and the product through-pass rate is greatly improved.
Description
The technical field is as follows:
the application belongs to the field of electronic component manufacturing, and particularly relates to an SMT (surface mount technology) template for mounting components on an internal circuit board of an electronic detonator.
Background art:
smt (surface Mounted technology), the most popular technique and process in the electronic assembly industry, is surface mount technology. The surface mount device (SMC/SMD, chip component) without pins or short leads is mounted on the surface of a Printed Circuit Board (PCB) or other substrates, and is soldered and assembled by methods such as reflow soldering or dip soldering.
The electronic detonator has extremely high requirement on the yield because of special product types (initiating explosive devices), and needs to reach PPM level, and 3% -5% of the reject ratio of the traditional civil electronic product production line can not meet the requirement.
As the patch elements become smaller, the intervals among the product components of the SMT steel mesh become smaller, and more defects occur. On a PCB production line, the fault distribution is approximately: the welding defects account for more than 75 percent and comprise bridging, insufficient welding, solder balls, tombstoning, insufficient soldering tin, excessive soldering tin and the like; the component errors account for 8% -10%, including polarity reversal, missing discharge, position errors, component errors and the like, and less than 10% of the remaining components are unqualified electrical parameters.
The high-precision chip mounter with the visual detection system and the infrared reflow soldering in the SMT steel mesh process are not main factors influencing the SMT product quality, 60% -90% of product quality defects appearing on a PCB are caused by silk-screen soldering paste, and the soldering paste printing is used as the first process of the SMT steel mesh, influences subsequent processes of chip mounting, reflow soldering, cleaning, testing and the like, and directly determines the reliability of products. Therefore, the screen printing is an important and key link in the SMT process. The method adopts a steel mesh (also called a template) with manufactured SMT, directly contacts the steel mesh with a printed board by a certain method, and when a scraper is pushed forwards on the template at a certain speed and angle, solder paste flows uniformly on the steel mesh and is extruded to be injected into steel meshes. When the steel mesh is separated from the printed board, the solder paste is separated from the steel mesh onto the corresponding pad pattern of the circuit board, thereby completing the printing of the solder paste on the printed board.
In the prior art, an SMT template is not improved to meet the high-precision requirement of the initiating explosive device industry.
The utility model has the following contents:
utility model purpose: the application aims to reduce and eliminate various defects during solder paste printing through improvement of the SMT template, and increase the final yield of products.
The technical scheme is as follows:
an SMT stencil, comprising: comprises a frame; the inner side of the frame is a plate body;
a soldering paste hole is formed in the board body according to the size of the element bonding pad;
the thickness of the plate body is as follows:
when the pad size L > 5W,
T＜W/1.5；
when the bonding pad is in the shape of a square or a circle,
T＜(L*W)/[1.32*(L+W)]；
wherein T is the thickness of the plate body, W is the width of the bonding pad, L is the length of the bonding pad, and when the bonding pad is circular, the values of L and W are the diameter of the bonding pad;
the surface of the plate body and the surface of the soldering paste hole are provided with coatings with the thickness of 20-30 nanometers.
The SMT stencil preferably: the joint of the frame and the periphery of the plate body is provided with a shock absorbing structure. Furthermore, the shock absorbing structure is an elastic connecting piece surrounding the plate body, and the elastic connecting piece is connected with the plate body and the frame.
The SMT stencil preferably: the frame is a square frame made of aluminum materials, and the outer edge of the frame is provided with a positioning groove.
The advantages and effects are as follows: the circuit board of the product is cleaner, and the reliability is improved; the special size of the soldering paste hole ensures that the tin climbing of the product is more full; the test shows that the records printed continuously for 13 ten thousand times on the production line do not fall off, so the cost is saved; the frequency of cleaning the steel mesh is reduced; the product first pass rate is greatly improved.
Description of the drawings:
FIG. 1 is a schematic illustration of the present application;
the figure is marked with: 1, an outer frame; 2, a shock absorbing structure; 3, a plate body; 4 solder paste apertures.
The specific implementation mode is as follows:
the technical idea of the application is that tin climbing is full, a circuit board of a product is cleaner, and the yield of the product is increased through the tin paste holes with special sizes on the template and the nano coating on the surface of the plate body.
The key point of the application is that the thickness of the welded welding pad is determined through the size of the welded welding pad, and the specific thickness is determined through the following formula:
when the pad size L > 5W,
T＜W/1.5；
when the bonding pad is in the shape of a square or a circle,
T＜(L*W)/[1.32*(L+W)]；
wherein T is the thickness of the board body, W is the width of the bonding pad, L is the length of the bonding pad, and when the bonding pad is circular, L and W are the diameters of the bonding pad.
I.e. the template thickness and pad size described in this application, correspond to the mathematical relationship of the above equation.
Example 1
In the embodiment, the pad has a long and narrow size, the length L is 6mm, and the width W is 1 mm;
the thickness of the template is 0.67mm, and the surfaces of the plate body and the surfaces of the soldering paste holes are provided with coatings with the thickness of 20 nanometers.
The periphery of the plate body is provided with a rubber shock absorption structure, and the periphery of the outer frame is provided with a positioning groove.
In the total 15000 experiments and patch production, tin climbing is obviously full, demoulding is clean, and tin hanging is not generated. The template is clean in the whole process of operation, and does not need to be cleaned.
Example 2
In the embodiment, the bonding pad is square, and the side length is 5.15 mm;
the thickness of the template is 1.95mm, and the surfaces of the plate body and the surfaces of the soldering paste holes are provided with plating layers with the thickness of 30 nanometers.
The periphery of the plate body is provided with a rubber shock absorption structure, and the periphery of the outer frame is provided with a positioning groove.
In 20000 experiments and patch production, tin climbing is obviously full, demoulding is clean, and tin hanging is not generated. The template is clean in the whole process of operation, and does not need to be cleaned.
Claims (4)
1. An SMT stencil, comprising: comprising a frame (1); the inner side of the frame (1) is provided with a plate body (3);
a soldering paste hole (4) is formed in the board body (3) according to the size of the element bonding pad;
the thickness of the plate body (3) is as follows:
when the pad size L > 5W,
T＜W/1.5；
when the bonding pad is in the shape of a square or a circle,
T＜(L*W)/[1.32*(L+W)]；
wherein T is the thickness of the plate body, W is the width of the bonding pad, L is the length of the bonding pad, and when the bonding pad is circular, the values of L and W are the diameter of the bonding pad;
the surface of the plate body (3) and the surface of the soldering paste hole (4) are provided with coatings with the thickness of 20-30 nanometers.
2. An SMT stencil according to claim 1, wherein: the joint of the periphery of the frame (1) and the plate body (3) is provided with a shock absorbing structure.
3. An SMT stencil according to claim 2, wherein: the shock-proof structure is an elastic connecting piece surrounding the plate body (3), and the elastic connecting piece is connected with the plate body (3) and the frame (1).
4. An SMT stencil according to claim 1, wherein: the frame (1) is a square frame made of aluminum materials, and the outer edge of the frame is provided with a positioning groove.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921916837.5U CN211047449U (en) | 2019-11-08 | 2019-11-08 | SMT template |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921916837.5U CN211047449U (en) | 2019-11-08 | 2019-11-08 | SMT template |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN211047449U true CN211047449U (en) | 2020-07-17 |
Family
ID=71536988
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201921916837.5U Active CN211047449U (en) | 2019-11-08 | 2019-11-08 | SMT template |
Country Status (1)
| Country | Link |
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| CN (1) | CN211047449U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115709349A (en) * | 2021-08-20 | 2023-02-24 | 北京小米移动软件有限公司 | Tin powder, preparation method of tin powder, tin paste, welding method of circuit board and circuit board |
-
2019
- 2019-11-08 CN CN201921916837.5U patent/CN211047449U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115709349A (en) * | 2021-08-20 | 2023-02-24 | 北京小米移动软件有限公司 | Tin powder, preparation method of tin powder, tin paste, welding method of circuit board and circuit board |
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