CN216253398U - Tin ball and tin paste preventing printing screen - Google Patents
Tin ball and tin paste preventing printing screen Download PDFInfo
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- CN216253398U CN216253398U CN202122857328.3U CN202122857328U CN216253398U CN 216253398 U CN216253398 U CN 216253398U CN 202122857328 U CN202122857328 U CN 202122857328U CN 216253398 U CN216253398 U CN 216253398U
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Abstract
The utility model provides a tin bead-resistant tin paste printing screen which comprises a printing screen body, wherein a plurality of first printing through holes are arranged on the printing screen body at intervals, each first printing through hole is provided with a concave part, each concave part is concave towards the inner side, every two adjacent first printing through holes form a group of first printing through hole groups, and in each group of first printing through hole groups, the two first printing through holes are oppositely arranged. According to the tin bead-preventing tin paste printing screen, the formation of tin beads is avoided through the structure of the first printing through holes; through the arrangement of the second printing through hole, missing printing and less tin are avoided; through setting up the boss, increase the height in steel mesh printing hole to guarantee the tin cream volume of corresponding component, design the structure of third printing through-hole simultaneously, can effectively avoid producing even tin. The tin bead and tin paste preventing printing screen greatly reduces the problems of short circuit and open circuit during welding, thereby ensuring good hardware connection and welding reliability.
Description
Technical Field
The utility model relates to the technical field of surface mounting, in particular to a tin bead and tin paste prevention printing screen.
Background
Surface Mount Technology (SMT) mainly includes: solder paste printing, precision taping, and reflow soldering, wherein the quality of solder paste printing has a great influence on the quality of surface mount products.
The application and coating process of the solder paste can be divided into two modes: one is to use a silk screen as a printing plate to print solder paste on a PCB, is suitable for mass production and application, and is the most common coating mode at present; the other is injection coating and solder paste jet printing, which is a screenless technique.
The printing screen is a mold for printing solder paste. In the SMT process, firstly, printing holes are formed in the corresponding positions of a screen according to the positions of pads on a printed circuit board, then solder paste is coated on the whole screen, then the solder paste is filled in the printing holes of the screen by using a scraper of a printing machine, then the screen is detached from the printed circuit board, so that the solder paste with fixed shape and thickness is left on the pads, then the component is attached to the printed circuit board, pins of the component are in contact with the solder paste, and then the printed circuit board is subjected to reflow soldering of the component in a reflow oven.
The solder ball is formed in the element body or the vicinity of the pad, because the solder paste may be extruded or collapsed beyond the pad for various reasons before soldering, and the solder paste beyond the pad is not melted with the solder paste on the pad and separated during soldering. Most of the tin beading occurs on both sides of the chip component. If the amount of the tin paste on the bonding pad is too large, the pressure when the element is attached can extrude the tin paste below the element body, the tin paste is hot melted during reflow soldering, the melted tin paste is converged into a round ball due to the action of surface energy, the round ball has the tendency of lifting the element, but the force is extremely small, the round ball is extruded to the two sides of the element by the gravity of the element and is separated from the bonding pad, and tin beads can be formed during cooling. If the gravity of the component is high and more solder paste is extruded, a plurality of solder balls are formed.
The appearance of the electronic product is affected by the tin beads around the element, and more importantly, because the density of the components of the printed circuit board is high and the distance between the components is small, the tin beads are likely to fall off when the product is used, so that the short circuit of the components is caused, and the quality and the reliability of the electronic product are affected.
In the process of surface mounting by using a silk screen, aiming at a fine-pitch integrated circuit with the pad pitch less than or equal to 0.2mm, the phenomenon of tin connection paste is easy to occur on the pad of a circuit board by coating tin paste on the silk screen plate, so that the problem of short circuit is caused, and the yield of device welding is influenced.
Some silk screens have too small printing holes, which easily cause missing printing and less tin, and cause insufficient soldering and bridging, and the silk screens have low yield and poor printing quality.
The process of applying solder paste on a PCB substrate, the amount of solder applied is a key factor affecting the quality of the solder, and the amount of solder is determined by the shape and size of the opening design of the screen. The good silk screen opening design and silk screen structure can guarantee good demoulding effect, can not cause welding short circuit, open a way to guarantee good hardware connection and welding reliability.
Therefore, it is desirable to provide a solder ball-proof solder paste printing screen to solve the above-mentioned problems.
SUMMERY OF THE UTILITY MODEL
The utility model provides a tin ball and tin paste printing screen, which aims to solve the problems of tin balls, continuous tin, missing printing and little tin caused by unreasonable opening design of the existing tin paste printing screen in the prior art.
In order to solve the technical problems, the technical scheme of the utility model is as follows: a solder ball resistant solder paste printing screen comprising: the printing screen comprises a printing screen body, wherein a plurality of first printing through holes are arranged on the printing screen body at intervals, each first printing through hole is provided with a concave part, each concave part is concave towards the inner side, every two adjacent first printing through holes form a group of first printing through hole groups, and in each group of first printing through hole groups, the two first printing through holes are arranged oppositely.
In the tin ball and tin paste preventing printing screen, the first printing through holes longitudinally penetrate through the printing screen body.
In the tin bead-resistant tin paste printing screen, the printing screen body comprises a substrate and at least one boss, the boss is arranged on the substrate, a plurality of second printing through holes are arranged on the substrate at intervals, a plurality of third printing through holes are arranged on the boss at intervals, and the distance between any two adjacent third printing through holes is smaller than 0.2 mm.
In the tin bead and tin paste preventing printing screen, the cross section of the boss is rectangular.
In the tin-bead-preventing tin paste printing screen, the cross section of the second printing through hole is in a T shape with one large end and the other small end, the small end of the second printing through hole is arranged close to the incoming direction of tin paste blade coating, and the large end of the second printing through hole is arranged close to the outgoing direction of the tin paste blade coating.
In the tin bead and tin paste preventing printing screen, the third printing through hole is at least provided with a chamfer.
In the tin ball and tin paste preventing printing screen, the second printing through hole longitudinally penetrates through the substrate, and the third printing through hole longitudinally penetrates through the boss and the substrate.
In the tin bead-proof tin paste printing screen, the inner walls of the first printing through holes, the second printing through holes and the third printing through holes are all provided with nano coatings.
In the tin-bead-preventing tin paste printing screen, the longitudinal section of at least one direction of the second printing through holes is trapezoidal, and the caliber of the second printing through holes is gradually increased from top to bottom.
In the tin ball-preventing tin paste printing screen, the upper part of the longitudinal section of at least one direction of the second printing through holes is trapezoidal, the lower part of the longitudinal section corresponding to the second printing through holes is rectangular, and the caliber of the second printing through holes is gradually increased from top to bottom.
Compared with the prior art, the utility model has the beneficial effects that: according to the tin bead-resistant tin paste printing screen, tin beads are prevented from being formed by the structure with the first printing through holes, missing printing and less tin are avoided by the structure with the second printing through holes, the height of the printing holes of the steel screen is increased by the arrangement of the bosses, so that the tin paste amount of corresponding components is ensured, and meanwhile, the structure with the third printing through holes is designed, so that continuous tin can be effectively avoided. The tin bead and tin paste preventing printing screen greatly reduces the problems of short circuit and open circuit during welding, thereby ensuring good hardware connection and welding reliability.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required in the embodiments are briefly introduced below, and the drawings in the following description are only corresponding to some embodiments of the present invention.
FIG. 1 is a schematic top view of a solder ball-resistant solder paste printing screen according to the present invention.
FIG. 2 is a schematic side view of a solder ball-resistant solder paste printing screen according to the present invention.
FIG. 3 is a schematic top view of the first printing through hole, the boss and the third printing through hole of the solder ball-proof solder paste printing screen according to the present invention
Fig. 4 is a schematic structural diagram of a substrate and a second printing through hole of a solder ball-proof solder paste printing screen according to a first embodiment of the utility model.
Fig. 5 is a schematic structural diagram of a substrate and a second printing through hole of a solder ball-proof solder paste printing screen according to a second embodiment of the utility model.
FIG. 6 is a schematic top view of a boss and a third printing through hole of the solder ball-resistant solder paste printing screen according to the present invention.
Wherein the content of the first and second substances,
1-printing a screen body, 11-first printing through holes, 111-concave parts, 12-substrate, 13-boss, 14-second printing through holes, and 15-third printing through holes.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the present invention, directional terms such as "up", "down", "front", "back", "left", "right", "inner", "outer", "side", "top" and "bottom" are used only with reference to the orientation of the drawings, and the directional terms are used for illustration and understanding of the present invention, and are not intended to limit the present invention.
The terms "first," "second," and the like in the terms of the utility model are used for descriptive purposes only and not for purposes of indication or implication relative importance, nor as a limitation on the order of precedence.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
The tin paste printing screen in the prior art is unreasonable in structure and is easy to generate tin beads, continuous tin, missing prints and few tin.
The following is a preferred embodiment of the present invention to provide a solder ball-proof solder paste printing screen that can solve the above technical problems.
Referring to fig. 1 to 6, fig. 1 is a schematic top view of a solder ball-resistant solder paste printing screen of the present invention, fig. 2 is a schematic side view of the solder ball-resistant solder paste printing screen of the present invention, fig. 3 is a schematic top view of a first printing through hole, a boss, and a third printing through hole of the solder ball-resistant solder paste printing screen of the present invention, fig. 4 is a schematic structural view of a substrate and a second printing through hole of a solder ball-resistant solder paste printing screen of a first embodiment of the present invention, fig. 5 is a schematic structural view of a substrate and a second printing through hole of a solder ball-resistant solder paste printing screen of a second embodiment of the present invention, and fig. 6 is a schematic top view of a boss and a third printing through hole of the solder ball-resistant solder paste printing screen of the present invention; the direction of the arrows in fig. 4 and 5 is the direction of the advancing blade.
In the drawings, elements having similar structures are denoted by the same reference numerals.
The utility model provides a tin bead and tin paste preventing printing screen, which comprises: the printing screen comprises a printing screen body 1, wherein a plurality of first printing through holes 11 are arranged on the printing screen body 1 at intervals, the first printing through holes 11 are provided with concave parts 111, the concave parts 111 are concave inwards, every two adjacent first printing through holes 11 form a group of first printing through hole groups, and in each group of first printing through hole groups, the two first printing through holes 11 are oppositely arranged; the concave part 111 may be arc-shaped or polygonal, according to the actual situation, but is not limited thereto; the calibers of the first printing through holes 11 are consistent up and down, so that the printing screen body 1 can be ensured to be smoothly separated; the existence of the concave part 111 can effectively avoid the generation of tin beads and improve the yield.
In the tin bead and tin paste preventing printing screen, a first printing through hole 11 longitudinally penetrates through a printing screen body 1; it can be understood that the first printing through hole 11 can be disposed on both the substrate 12 and the boss 13, when the first printing through hole 11 is disposed on the substrate 12, the first printing through hole 11 longitudinally penetrates through the substrate 12, and when the first printing through hole 11 is disposed on the boss 13, the first printing through hole 11 longitudinally penetrates through the substrate 12 and the boss 13, it can be understood that the solder paste enters the pad through the first printing through hole 11, and when the printing screen body 1 is detached, the solder paste with fixed shape and thickness is left on the pad.
In the tin ball and tin paste prevention printing screen, the printing screen body 1 comprises a substrate 12 and at least one boss 13, the boss 13 is arranged on the substrate 12, a plurality of second printing through holes 14 are arranged on the substrate 12 at intervals, a plurality of third printing through holes 15 are arranged on the boss 13 at intervals, and the distance between any two adjacent third printing through holes 15 is less than 0.2 mm.
It will be understood that other types of printed through holes may be provided in the base 12 and the boss 13, as the case may be, and are not limited thereto.
Due to the processing requirement of the circuit board, the distance between the third printing through holes 15 is small, so that the amount of solder paste corresponding to the third printing through holes 15 is possibly small, the amount of solder paste in the third printing through holes 15 is increased through the arrangement of the bosses 13, and the stability of the subsequent over-flow welding process is ensured.
Preferably, the printing screen body 1 is a steel screen, and of course, other materials can be selected to make the printing screen body 1, which is determined according to the actual situation and is not limited to this; the base plate 12 is integrally formed with the boss 13.
Generally, the number of the third printing through holes 15 arranged on the boss 13 is greater than 5, the number of the arrangement is determined according to the actual situation, the third printing through holes 15 arranged on the boss 13 form a dense printing through hole set, the number of the bosses 13 is determined according to the actual situation, and the arrangement of the bosses 13 is subject to the condition that the bosses 13 and the movement tracks of the bosses 13 and the scraper do not interfere with each other; the third printing through holes 15 have smaller intervals, so the calibers of the third printing through holes 15 are consistent up and down; thereby ensuring that the printing screen body 1 is smoothly released.
In the tin ball and tin paste preventing printing screen, the cross section of the lug boss 13 is rectangular, so that the space utilization rate of the printing screen body 1 can be improved.
In the tin-bead-preventing tin paste printing screen, the cross section of the second printing through hole 14 is in a T shape with one large end and the other small end, the small end of the second printing through hole 14 is arranged close to the incoming direction of tin paste blade coating, and the large end of the second printing through hole 14 is arranged close to the outgoing direction of the tin paste blade coating, so that the large end of the second printing through hole 14 can contain more tin paste, and the problem that less tin appears at the rear end of the second printing through hole 14 by the tin paste is avoided.
In the tin bead-resistant tin paste printing screen, the third printing through holes 15 are at least provided with the chamfer, so that the distance between the adjacent third printing through holes 15 can be ensured, the possibility of forming continuous tin between the adjacent third printing through holes 15 can be reduced, and the yield is improved.
In the tin-bead-preventing tin paste printing screen, the second printing through hole 14 longitudinally penetrates through the substrate 12, and the third printing through hole 15 longitudinally penetrates through the boss 13 and the substrate 12, so that the tin paste respectively enters a welding pad through the second printing through hole 14 and the third printing through hole 15, and when the printing screen body 1 is detached, the tin paste with fixed shape and thickness is left on the welding pad.
In the tin ball and tin paste preventing printing screen, the inner walls of the first printing through hole 11, the second printing through hole 14 and the third printing through hole 15 are all provided with nano coatings; generally, a nano coating is sprayed or coated on the inner walls of the first printing through hole 11, the second printing through hole 14 and the third printing through hole 15 by a spraying or coating method, the thickness of the nano coating is generally 100-500 nm, the nano coating not only can improve the hardness of the printing screen body 1, but also has super-hydrophobicity, so that the residues of solder paste on the first printing through hole 11, the second printing through hole 14 and the third printing through hole 15 can be reduced, and the demolding effect and poor printing can be greatly improved.
Referring to fig. 4, fig. 4 is a schematic structural view of a substrate and a second printing through hole of a solder ball-proof solder paste printing screen according to an embodiment of the utility model.
In the tin ball and tin paste preventing printing screen, the longitudinal section of at least one direction of the second printing through hole 14 is trapezoidal, and the caliber of the second printing through hole 14 is gradually increased from top to bottom; therefore, after the scraper finishes coating the solder paste, the printing screen body 1 can be favorably separated; the longitudinal section of the second printing through hole 14 may be a Y-direction longitudinal section, or a Z-direction longitudinal section, and when the Y-direction longitudinal section of the second printing through hole 14 is trapezoidal, the Z-direction longitudinal section of the second printing through hole 14 may be trapezoidal, the Z-direction longitudinal section of the second printing through hole 14 may also be rectangular, or of course, other shapes may be adopted, based on the fact that the aperture of the second printing through hole 14 is small in top and large in bottom, and the printing screen body 1 is smoothly pulled out; when the Z-direction longitudinal section of the second printing through hole 14 is trapezoidal, the Y-direction longitudinal section of the second printing through hole 14 may be trapezoidal, and the Y-direction longitudinal section of the second printing through hole 14 may also be rectangular, or of course, may have other shapes, based on the fact that the aperture of the second printing through hole 14 is small in top and large in bottom, and the printing screen body 1 is smoothly pulled out.
Referring to fig. 5, fig. 5 is a schematic structural diagram of the substrate 12 and the second printing through holes 14 of the solder ball-proof solder paste printing screen according to the second embodiment of the utility model.
In the second embodiment of the tin ball and tin paste preventing printing screen, the upper part of the longitudinal section of at least one direction of the second printing through hole 14 is trapezoidal, the width of the upper part of the second printing through hole 14 in the corresponding direction is gradually increased from top to bottom, and the lower part of the longitudinal section of the second printing through hole 14 in the corresponding direction is rectangular; therefore, after the scraper finishes coating the solder paste, the separation of the printing screen body 1 can be facilitated, and because the lower part of the longitudinal section of the second printing through hole 14 is rectangular, the phenomenon that the solder paste is not fully filled at the bottom of the second printing through hole 14 due to a small included angle can be avoided, the problem of open circuit is avoided, and the yield is improved; the longitudinal section of the second printing through hole 14 may be a Y-direction longitudinal section, or a Z-direction longitudinal section, and when the upper portion of the Y-direction longitudinal section of the second printing through hole 14 is trapezoidal, the Z-direction longitudinal section of the second printing through hole 14 may be trapezoidal, and the Z-direction longitudinal section of the second printing through hole 14 may also be rectangular, or of course, other shapes may be adopted, based on the fact that the caliber of the second printing through hole 14 is small at the top and large at the bottom, and the printing screen body 11 is smoothly pulled out; when the upper portion of the Z-direction longitudinal section of the second printing through hole 14 is trapezoidal, the Y-direction longitudinal section of the second printing through hole 14 may be trapezoidal, and the Y-direction longitudinal section of the second printing through hole 14 may also be rectangular, or of course, may be in other shapes, based on the fact that the aperture of the second printing through hole 14 is small in the top and large in the bottom, and the printing screen body 1 is smoothly pulled out.
The working principle of the utility model is as follows:
coating solder paste on the front end of the substrate 12, and scraping the solder paste by a scraper in sequence from front to back to cover the substrate 12 with the solder paste, so that the solder paste enters the bonding pad through the second printing through hole 14, and if the substrate 12 is provided with the first printing through hole 11, the solder paste also enters the bonding pad through the first printing through hole 11;
coating solder paste on the front end of the boss 13, and scraping the solder paste by a scraper in sequence from front to back to cover the boss 13 with the solder paste, so that the solder paste enters the bonding pad through the third printing through hole 15, and if the substrate 12 is provided with the first printing through hole 11, the solder paste also enters the bonding pad through the first printing through hole 11;
the sequence of the scraper blade coating of the substrate 12 and the boss 13 is determined according to actual conditions, the substrate 12 can be blade coated first and then the boss 13 can be blade coated, the boss 13 can be blade coated first and then the substrate 12 can be blade coated, and blade coating can also be simultaneously performed.
Thus, the operation of the solder ball-proof solder paste printing screen of the preferred embodiment is completed.
In summary, although the present invention has been described with reference to the preferred embodiments, the above-described preferred embodiments are not intended to limit the present invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, therefore, the scope of the present invention shall be determined by the appended claims.
Claims (10)
1. A tin ball and tin paste preventing printing screen is characterized by comprising: the printing screen comprises a printing screen body, wherein a plurality of first printing through holes are arranged on the printing screen body at intervals, each first printing through hole is provided with a concave part, each concave part is concave towards the inner side, every two adjacent first printing through holes form a group of first printing through hole groups, and in each group of first printing through hole groups, the two first printing through holes are arranged oppositely.
2. The anti-stiction solder paste printing screen according to claim 1, wherein the first printing through holes penetrate the printing screen body longitudinally.
3. The tin ball and tin paste printing screen as claimed in claim 1, wherein the printing screen body comprises a substrate and at least one boss, the boss is arranged on the substrate, a plurality of second printing through holes are arranged on the substrate at intervals, a plurality of third printing through holes are arranged on the boss at intervals, and the distance between any two adjacent third printing through holes is less than 0.2 mm.
4. The anti-stiction solder paste printing screen according to claim 3, wherein the cross-section of the bosses is rectangular.
5. The tin-bead-proof tin paste printing screen as claimed in claim 3, wherein the cross section of the second printing through hole is in a T shape with one large end and the other small end, the small end of the second printing through hole is arranged close to the direction of tin paste scraping, and the large end of the second printing through hole is arranged close to the direction of the tin paste scraping.
6. The anti-stiction solder paste printing screen according to claim 3, wherein the third printing through holes are provided with at least one chamfer.
7. The anti-stiction solder paste printing screen of claim 3, wherein the second printing through hole penetrates the substrate longitudinally and the third printing through hole penetrates the boss and the substrate longitudinally.
8. The anti-beading solder paste printing screen of claim 3, wherein the inner walls of the first printing through holes, the second printing through holes and the third printing through holes are all provided with nano-coatings.
9. The anti-beading solder paste printing screen according to claim 3, wherein the second printing through holes have a trapezoidal longitudinal section in at least one direction, and the diameter of the second printing through holes is gradually increased from top to bottom.
10. The tin ball and tin paste printing screen as claimed in claim 3, wherein the upper part of the longitudinal section of the second printing through hole in at least one direction is trapezoidal, the lower part of the longitudinal section corresponding to the second printing through hole is rectangular, and the caliber of the second printing through hole is gradually increased from top to bottom.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122857328.3U CN216253398U (en) | 2021-11-19 | 2021-11-19 | Tin ball and tin paste preventing printing screen |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122857328.3U CN216253398U (en) | 2021-11-19 | 2021-11-19 | Tin ball and tin paste preventing printing screen |
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| Publication Number | Publication Date |
|---|---|
| CN216253398U true CN216253398U (en) | 2022-04-08 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202122857328.3U Active CN216253398U (en) | 2021-11-19 | 2021-11-19 | Tin ball and tin paste preventing printing screen |
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| CN (1) | CN216253398U (en) |
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2021
- 2021-11-19 CN CN202122857328.3U patent/CN216253398U/en active Active
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