Automatic solder paste printing device and method for BGA chip

Abstract

The embodiment of the invention discloses an automatic solder paste printing device for a BGA chip. The printing device comprises a screen plate, a shape variable part, a scraper and a first shape switching part. When the shape variable piece is in the first shape, at least part is located in the hole. When in the second shape, the shape variable part is located outside the hole. And the scraper is used for scraping the solder paste on the screen plate when the shape variable part is in the first shape, so that the solder paste is leaked to the bonding pad of the BGA chip through the hole, and then a solder paste body is formed on the bonding pad. The first shape switching part is used for driving the shape variable part to be switched from the first shape to the second shape, so that the solder paste can fill a gap formed in the shape variable part in a self-leveling mode, and then the thickness of the solder paste is reduced. The embodiment of the invention provides another solder paste printing mode to realize the thickness difference of the solder paste.

Description

Technical Field

[0001] The present application relates to the technical field of BGA (Ball Grid Array) chip manufacturing, and in particular to an automatic solder paste printing device and method for BGA chips. Background Art

[0002] To increase chip integration, most IC products currently use BGA (Ball Grid Array) packaging. The BGA chip bumping process involves applying a layer of solder paste to the BGA chip's pads using a stencil coating method. Tiny solder balls are then precisely placed onto the corresponding pads. Reflow soldering melts the solder balls and forms a solid bond with the pads. The stencil coating process involves creating multiple holes in a stencil (the hole location and shape are determined by the chip's pad location and size). After aligning the holes with the pads, a printer uses a solder paste scraper to apply pressure to the stencil at a specific angle and speed, depositing solder paste onto the pads beneath the stencil to form a paste layer. The thickness of the solder paste formed by stencil coating is determined by the stencil's thickness. Since the stencil is uniform in thickness, the solder paste is essentially the same across multiple pads.

[0003] To achieve differentiated thickness of the solder paste formed on different pads, the prior art uses a stepped stencil for solder paste printing. Specifically, the amount of solder paste printed is increased by thickening a portion of the stencil, or reduced by thinning a portion of the stencil. Adjusting the thickness of a portion of the stencil creates a stepped shape on the surface of the stencil. If the stepped shape of the stencil is located on the upper surface, it can easily result in the scraper not being able to fit tightly against the stencil. If the stepped shape of the stencil is located on the lower surface, it can easily result in loose contact between the chip and the stencil, thereby affecting the quality of solder paste printing. Summary of the Invention

[0004] The embodiments of the present application provide an automatic solder paste printing device and method for a BGA chip, and provide another solder paste printing method to achieve thickness differentiation of the solder paste.

[0005] In order to solve the above technical problems, the embodiments of the present application disclose the following technical solutions: On the one hand, a BGA chip automatic solder paste printing device is provided, comprising a stencil, a shape-variable member, a scraper, and a first shape-switching member. The stencil is provided with a hole extending through the stencil in the thickness direction. The shape-variable member can selectively be in a first shape and a second shape. In the first shape, at least a portion of the shape-variable member is located in the hole, and in the second shape, the shape-variable member is located outside the hole. The scraper is used to scrape the solder paste on the stencil when the shape-variable member is in the first shape, so that the solder paste leaks through the hole onto the pad of the BGA chip, thereby forming a solder paste body on the pad. The first shape-switching member is used to drive the shape-variable member to switch from the first shape to the second shape, so that the solder paste body can self-level and fill the gap formed at the shape-variable member, thereby reducing the thickness of the solder paste body.

[0006] In addition to or as an alternative to one or more of the features disclosed above, the shape-variable member is connected to the edge of the hole. In the first shape, the shape-variable member protrudes from the edge of the hole toward the center area of the hole and is entirely located in the hole. In the second shape, the shape-variable member is located on the side of the stencil away from the pad in the thickness direction.

[0007] In addition to or as an alternative to one or more of the features disclosed above, in the first shape, the shape-variable member does not protrude from a surface of the stencil on a side facing away from the pad in a thickness direction of the stencil.

[0008] In addition to or as an alternative to one or more of the features disclosed above, the shape-variable member includes a first portion and a second portion. The first portion is in a closed annular shape, surrounding a notch. The second portion is connected between the edge of the hole and the first portion. In the first shape, the notch extends through the first portion in the thickness direction of the mesh.

[0009] In addition to or as an alternative to one or more of the features disclosed above, the shape-variable member is made of a shape-memory metal, wherein within a first predetermined temperature range, the shape-variable member is in a first shape, and within a second predetermined temperature range, the shape-variable member is in a second shape, wherein the temperature value in the second predetermined temperature range is greater than the temperature value in the first predetermined temperature range. The first shape-switching member is configured to heat the shape-variable member so that the temperature of the shape-variable member is within the second predetermined temperature range.

[0010] In addition to or as an alternative to one or more of the features disclosed above, the first shape-switching member includes a laser generator, which is configured to emit a laser beam and irradiate the shape-changing member to heat the shape-changing member.

[0011] In addition to one or more of the features disclosed above, or as an alternative, the BGA chip automatic solder paste printing device further includes a second shape switching member, which is used to drive the shape-variable member to switch from the second shape to the first shape.

[0012] In addition to or as an alternative to one or more of the features disclosed above, the shape-shifting member is made of a shape-memory metal, wherein within a first predetermined temperature range, the shape-shifting member is in a first shape, and within a second predetermined temperature range, the shape-shifting member is in a second shape, wherein the temperature value within the second predetermined temperature range is greater than the temperature value within the first predetermined temperature range. The second shape-shifting member is configured to cool the shape-shifting member to maintain the temperature of the shape-shifting member within the first predetermined temperature range.

[0013] In addition to or as an alternative to one or more of the features disclosed above, the second shape-switching member includes a fan configured to blow airflow toward the shape-variable member to cool the shape-variable member.

[0014] In addition to or as an alternative to one or more of the features disclosed above, the BGA chip automatic solder paste printing device further includes a vibration generator, which is used to apply high-frequency vibration to the BGA chip to promote self-leveling of the solder paste.

[0015] In addition to or as an alternative to one or more of the features disclosed above, the automatic solder paste printing device for BGA chips also includes a turntable, which is rotatable and used to carry the BGA chip, and a first working area and a second working area are arranged at intervals in the circumference of the turntable. There are multiple stencils, which are respectively arranged on the turntable and arranged at intervals in the circumference of the turntable. When one stencil is in the first working area, the other stencil is in the second working area; there are multiple shape-variable members, which are respectively arranged on the turntable, and each stencil is correspondingly provided with a predetermined number of shape-variable members; a scraper is arranged in the first working area, and the scraper is used to scrape the solder paste on the stencil located in the first working area; a first shape switching member is arranged in the second working area, and the first shape switching member is used to drive the shape-variable member located in the second working area to switch from a first shape to a second shape.

[0016] In addition to or as an alternative to one or more of the features disclosed above, the BGA chip automatic solder paste printing device further includes a plurality of carriers, each of which is detachably mounted on the turntable and spaced apart circumferentially around the turntable. When one carrier is located in the first working area, another carrier is located in the second working area. The carriers are used to carry the BGA chip and the stencil. The BGA chip and the stencil are respectively mounted on the turntable via the carriers. The stencils correspond one-to-one to the carriers, and each stencil is mounted on a corresponding carrier.

[0017] On the other hand, a method for automatic solder paste printing of BGA chips is also provided, comprising the following steps: When the shape-adjustable member is in a first shape, the scraper scrapes the solder paste on the stencil so that the solder paste leaks through the holes in the stencil onto the pads of the BGA chip, thereby forming a solder paste body on the pads. The holes penetrate the stencil in the thickness direction of the stencil. When in the first shape, at least a portion of the shape-adjustable member is located in the holes. The shape-variable member is driven by the first shape-switching member to switch from the first shape to the second shape, so that the solder paste can self-level and fill the gap formed at the shape-variable member, thereby reducing the thickness of the solder paste. In the second shape, the shape-variable member is located outside the hole.

[0018] One of the above technical solutions has the following advantages or beneficial effects: In an embodiment of the present application, during the scraper scraping the solder paste on the stencil, at least a portion of the shape-variable member is located in the hole, so that the volume of the solder paste formed by leaking through the hole onto the solder pad is smaller than the volume of the hole. After the shape-variable member exits the hole, the solder paste forms a gap at the corresponding variable member. After the solder paste self-levels and fills the gap formed at the shape-variable member, the thickness of the solder paste decreases. In other words, compared to the hole not affected by the shape-variable member, the volume of the solder paste formed at the hole affected by the shape-variable member is reduced, which naturally leads to a reduction in its thickness, thereby achieving thickness differentiation of the solder paste. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings will make the technical solutions and other beneficial effects of the present application apparent.

[0020] Figure 1 This is a top view of the printing device of the present application in use; Figure 2 yes Figure 1 A schematic diagram of the three-dimensional structure of the printing device shown; Figure 3 This is a schematic diagram of a three-dimensional structure of a printed template installed on a carrier in one embodiment of the present application; Figure 4 yes Figure 3 3D exploded view of the printed template and carrier; Figure 5 yes Figure 3 3D exploded view of the printed template; Figure 6 yes Figure 3 A partial schematic diagram of the E1-E1 section; Figure 7 3D schematic diagram of the loading assembly in one embodiment of the present application; Figure 8 3D schematic diagram of the scraper assembly in one embodiment of the present application; Figure 9yes Figure 8 A top view of the scraper assembly in use; Figure 10 This is a schematic diagram of a local structure of a printing template in one embodiment of the present application; Figure 11 When the shape-variable member is in the first shape, Figure 10 Sectional view of E2-E2; Figure 12 When the shape-variable member is in the second shape, Figure 10 Sectional view of E2-E2; Figure 13 3D schematic diagram of the thickness reduction component in one embodiment of the present application; Figure 14 yes Figure 13 A side view of the thickness reduction assembly shown in use; Figure 15 It is a schematic diagram of forming solder paste on the pad of BGA chip in the printed area; Figure 16 It is a schematic diagram of forming solder paste on the pad of BGA chip in the reduced thickness area; Figure 17 yes Figure 16 E3-E3 cross-section in; Figure 18 This is a flow chart of the automatic solder paste printing method for BGA chips of this application.

[0021] Description of reference numerals: 10-turntable; 20-vibration generator; 30-carrier; 40-printing template; 410-limiting member; 420-screen; 421-hole; 430-shape-variable member; 431-first part; 432-second part; 433-notch; 50-feeding assembly; 510-first conveyor; 520-first driving member; 530-first clamping jaw; 60-scraping assembly; 610-second driving member; 620-third driving member; 630 -scraper; 70-thickness reduction component; 710-fourth driving member; 720-fifth driving member; 730-sixth driving member; 740-first shape switching member; 80-unloading component; 90-BGA chip; 910-soldering pad; 920-tin paste; 920A-first tin paste; 920B-second tin paste; X-longitudinal; Y-horizontal; Z-vertical; Z1-loading area; Z2-printing area; Z3-thickness reduction area; Z4-unloading area. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and beneficial effects of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and specific implementation methods. It should be understood that the specific implementation methods described in this specification are only for the purpose of explaining this application and are not intended to limit this application.

[0023] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, the meaning of "multiple" refers to two or more, unless otherwise clearly and specifically defined.

[0024] The present application provides an automatic solder paste printing device for BGA chips, hereinafter referred to as a printing device. The printing device is used to apply solder paste to the pads 910 of the BGA chip.

[0025] See also Figure 1 and Figure 2 . Figure 1 It is a top view of the printing device of the present application in use. Figure 2 yes Figure 1 Schematic diagram of the three-dimensional structure of the printing device shown. Figure 2 The loading component 50 is omitted.

[0026] The printing device includes a turntable 10, which is rotatably arranged. Specifically, the turntable 10 is rotatably arranged on the machine platform, and the rotation axis of the turntable 10 is parallel to the vertical direction Z.

[0027] The printing device further includes a plurality of vibration generators 20. Each vibration generator 20 is disposed on the turntable 10. The vibration generator 20 is used to generate high-frequency vibration. Figure 1 In the embodiment, there are four vibration generators 20, and the four vibration generators 20 are arranged in a clockwise direction.

[0028] The printing device also includes multiple carriers 30. Each carrier 30 can be removably mounted on the vibration generator 20. The carriers 30 are used to carry BGA chips. The carriers 30 carry the BGA chips along the production line. For example, after solder paste printing is completed, the carriers 30 carry the BGA chips to the automated ball placement device, where solder balls are placed on the pads 910 of the BGA chips.

[0029] See also Figures 3 to 6 . Figure 3 FIG. 4 is a schematic diagram of a three-dimensional structure of a printing template 40 installed on a carrier 30 in one embodiment of the present application. Figure 4 yes Figure 3 A three-dimensional exploded view of the printing template 40 and the carrier 30. Figure 5 yes Figure 3 A three-dimensional exploded view of the printed template 40. Figure 6 yes Figure 3 Partial schematic diagram of the E1-E1 section.

[0030] The printing device further comprises a plurality of printing templates 40 . Figure 1 In the printing device shown, three printing templates 40 can complete the turnover. The printing template 40 can be detachably mounted on the carrier 30. Each carrier 30 can carry multiple BGA chips 90.

[0031] The printing template 40 includes a limiting member 410, a stencil 420, and at least one shape-changing member 430 (described in detail below). The stencil 420 is generally flat and has a plurality of holes 421 extending through it along the thickness direction. The stencil 420 is fixed to the limiting member 410. The limiting member 410 is used to limit and cooperate with the carrier 30 so that the stencil 420 is in a predetermined position relative to the BGA chip 90 on the carrier 30. When the printing template 40 is installed on the carrier 30, the stencil 420 covers the BGA chip, and the holes 421 correspond one-to-one with the solder pads 910 on the BGA chip 90. The solder pads 910 leak out through the corresponding holes 421. The printing template 40 (stencil 420) is used to apply solder paste to the solder pads 910 of the BGA chip 90 to form a solder paste body 920.

[0032] See also Figure 1 and Figure 2 The printing device also includes a loading assembly 50, a scraping assembly 60, a thickness reduction assembly 70, and a blanking assembly 80. These assemblies are arranged clockwise around the turntable 10. The locations of the loading assembly 50, scraping assembly 60, thickness reduction assembly 70, and blanking assembly 80 are designated as the loading area Z1, printing area Z2, thickness reduction area Z3, and blanking area Z4, respectively.

[0033] The turntable 10 moves intermittently and rotates at a fixed angle, with a predetermined time interval between each rotation. When the turntable 10 is stationary, the four areas are each provided with a carrier 30. Each rotation of the turntable 10 causes the carrier 30 to switch positions between the four areas.

[0034] The loading assembly 50 is used to install the carrier 30 (carrying the BGA chip) transferred from the previous process onto the vibration generator 20 , and to remove the printed template 40 from the carrier 30 in the unloading area Z4 and install it onto the carrier 30 in the loading area Z1 .

[0035] The scraper assembly 60 is used to scrape the solder paste through the scraper 630 so that the solder paste leaks through the holes 421 on the printing template 40 onto the pads 910 of the BGA chip, thereby forming a solder paste body 920 on the pads 910 .

[0036] The thickness reducing component 70 is used to reduce the thickness of the solder paste 920 on the BGA chip on the carrier 30 .

[0037] The unloading assembly 80 is used to remove the carrier 30 from the vibration generator 20 and transfer it to the next process (such as the ball planting process).

[0038] In the embodiment of the present application, the loading operation, printing operation, thinning operation and unloading operation are performed simultaneously, which can improve work efficiency.

[0039] The specific operations of each area are described in detail below.

[0040] Loading area Z1. See Figure 7 . Figure 7 It is a schematic diagram of the three-dimensional structure of the loading assembly 50 in one embodiment of the present application.

[0041] The loading assembly 50 includes a first conveyor 510, a first drive member 520, and a first gripper 530. The first gripper 530 is disposed at the drive end of the first drive member 520. The first drive member 520 is capable of driving the first gripper 530 to move in three-dimensional space. The first gripper 530 is used to grasp or release an object. In some embodiments, the first drive member 520 includes a first linear motor, a second linear motor, and a third linear motor. The second linear motor is disposed at the drive end of the first linear motor, the third linear motor is disposed at the drive end of the second linear motor, and the first gripper 530 is disposed at the drive end of the third linear motor. The first linear motor is capable of driving the second linear motor to reciprocate in the vertical direction Z. The second linear motor is capable of driving the third linear motor to reciprocate in the horizontal direction Y. The third linear motor is capable of driving the first gripper 530 to reciprocate in the longitudinal direction X. Any two of the vertical direction Z, the horizontal direction Y, and the longitudinal direction X are perpendicular to each other. In other embodiments, the first drive member 520 is a robotic arm.

[0042] The first conveyor 510 is used to transport carriers 30 (carrying BGA chips) from the previous process to the loading area Z1. The first driver 520 drives the first clamping jaw 530 to move the carriers 30 on the first conveyor 510 onto the vibration generator 20 in the loading area Z1. The first driver 520 drives the first clamping jaw 530 to move the printing template 40 from the unloading area Z4 onto the carrier 30 in the loading area Z1.

[0043] Printing area Z2. See Figure 8 and Figure 9 . Figure 8 Schematic diagram of the three-dimensional structure of the scraper assembly 60 in one embodiment of the present application (some parts are omitted to clearly see the scraper 630). Figure 9 yes Figure 8 The scraper assembly 60 is shown in a top view in use.

[0044] The scraper assembly 60 includes a second drive member 610, a third drive member 620, scrapers 630 (two in the figure), and a solder paste supply member (not shown). The second drive member 610 is disposed on the machine table. The third drive member 620 is disposed at the driving end of the second drive member 610. The second drive member 610 can drive the third drive member 620 to reciprocate in the vertical direction Z. The third drive member 620 is, for example, a linear motor, and the second drive member 610 is disposed at the moving end of the linear motor. The scraper 630 is disposed at the driving end of the third drive member 620. The third drive member 620 can drive the scraper 630 to reciprocate in the longitudinal direction X. The third drive member 620 is, for example, a cylinder. The scraper 630 is disposed on the piston rod of the cylinder. The scraper 630 can be made of an elastic material. The solder paste supply member is used to supply solder paste.

[0045] When the carrier 30 carrying the BGA chip and the printing template 40 moves to the printing area Z2, the second driving member 610 drives the third driving member 620 downward, causing the scraper 630 to press against the top surface of the printing template 40. The solder paste supply member supplies solder paste to the top surface of the printing template 40. The third driving member 620 drives the scraper 630 to move in the longitudinal direction X, causing the scraper 630 to scrape the solder paste, which then flows through the holes 421 and onto the pads 910, forming a solder paste body 920. In some embodiments, a solder paste recovery member (not shown) is also provided to recover excess solder paste. The second driving member 610 drives the third driving member 620 upward, separating the scraper 630 from the printing template 40 and resetting it in the vertical direction Z. The third driving member 620 drives the scraper 630 to reposition in the horizontal direction Y.

[0046] See also Figure 10 、 Figure 11 and Figure 12 . Figure 10 4 is a schematic diagram of a local structure of the printing template 40 when the shape-variable member 430 is in the first shape in one embodiment of the present application. Figure 11When the shape-variable member 430 is in the first shape, Figure 10 Cross-sectional view of E2-E2. Figure 12 When the shape-variable member 430 is in the second shape, Figure 10 Cross-sectional view of E2-E2.

[0047] As mentioned above, the printing template 40 includes a shape-variable member 430. The shape-variable member 430 can selectively assume a first shape and a second shape. In the first shape, at least a portion of the shape-variable member 430 is located within the hole 421. In the second shape, the shape-variable member 430 is located outside the hole 421.

[0048] When the shape-adjustable member 430 is in the first shape, the scraper 630 scrapes the solder paste on the stencil 420, allowing the solder paste to flow through the holes 421 onto the pads 910 of the BGA chip, thereby forming a body of solder paste 920 on the pads 910. In printing zone Z2, the shape-adjustable member 430 in the printing template 40 on the carrier 30 remains in the first shape. Because a portion of the shape-adjustable member 430 is located within the hole 421, the amount of solder paste filling the hole 421 is less than the volume of the hole 421 (excluding the shape-adjustable member 430).

[0049] The number and location of the shape-variable members 430 are determined as needed. Specifically, in one application scenario, some of the holes 421 of the mesh 420 are provided with shape-variable members 430 , while other holes 421 are not provided with shape-variable members 430 .

[0050] In some embodiments, the shape-variable member 430 is connected to the edge of the hole 421. In a first shape, the shape-variable member 430 protrudes from the edge of the hole 421 toward the center of the hole 421 and is entirely located within the hole 421. In a second shape, the shape-variable member 430 is located on the side of the stencil 420 facing away from the pad 910 in the thickness direction. In other embodiments, the shape-variable member 430 can also be provided independently of the stencil 420. For example, the shape-variable member 430 can be connected to the carrier 30, or can be removably mounted to the carrier 30, or can be fixed to the machine platform.

[0051] In some embodiments, in the first shape, the shape-variable member 430 does not protrude from the surface of the stencil 420 facing away from the pad 910 in the thickness direction of the stencil 420. During the movement of the scraper 630, the shape-variable member 430 does not interfere with the scraper 630, thereby avoiding reducing printing quality.

[0052] In some embodiments, the shape-variable member 430 includes a first portion 431 and a second portion 432. The first portion 431 is a closed ring, defining a gap 433. The second portion 432 is connected between the edge of the hole 421 and the first portion 431. In the first shape, the gap 433 extends through the first portion 431 along the thickness of the mesh 420. The shape-variable member 430 may also employ other structural forms.

[0053] See also Figure 13 and Figure 14 . Figure 13 3D schematic diagram of the thickness reduction component 70 in one embodiment of the present application. Figure 14 yes Figure 13 The thickness reduction assembly 70 is shown in a side view in use.

[0054] In some embodiments, the thickness reduction component 70 includes a fourth driving member 710, a fifth driving member 720, a sixth driving member 730 and a first shape switching member 740 (six in the figure). The fourth driving member 710 is arranged on the machine. The fifth driving member 720 is arranged at the driving end of the fourth driving member 710. The fourth driving member 710 can drive the fifth driving member 720 to reciprocate in the longitudinal direction X. The sixth driving member 730 is arranged at the driving end of the fifth driving member 720. The fifth driving member 720 can drive the sixth driving member 730 to reciprocate in the vertical direction Z. The first shape switching member 740 is arranged at the driving end of the sixth driving member 730. The sixth driving member 730 can drive the first shape switching member 740 to rotate with the horizontal axis Y as the axis.

[0055] The fourth driving member 710 , the fifth driving member 720 and the sixth driving member 730 cooperate with each other to adjust the position and posture of the first shape switching member 740 .

[0056] The first shape switching member 740 is used to drive the shape-changing member 430 to switch from the first shape to the second shape, so that the solder paste 920 can self-level and fill the gap formed at the shape-changing member 430, thereby reducing the thickness of the solder paste 920.

[0057] In the reduced thickness region Z3, after the shape-variable member 430 switches from the first shape to the second shape, the vibration generator 20 is used to apply high-frequency vibrations to the BGA chip to promote self-leveling of the solder paste 920. Specifically, the vibration generator 20 applies high-frequency vibrations to the carrier 30, thereby applying high-frequency vibrations to the BGA chip and the printing template 40 carried by the carrier 30.

[0058] See also Figure 15 、 Figure 16 and Figure 17 . Figure 15FIG. 1 is a schematic diagram of forming a solder paste 920 on a pad 910 of a BGA chip 90 in a printing area Z2 , wherein the solder paste 920 is highlighted by adding a cross-hatching line. Figure 16 FIG. 1 is a schematic diagram of forming a solder paste 920 on a pad 910 of a BGA chip in a reduced thickness area Z3 , wherein the solder paste 920 is highlighted by adding a cross-hatching line. Figure 17 yes Figure 16 E3-E3 cross-section diagram in.

[0059] Figures 15 to 17 In the embodiment, the first solder paste 920A is formed at the hole 421 where the shape-variable member 430 is not provided, and the second solder paste 920B is formed at the hole 421 where the shape-variable member 430 is provided.

[0060] After shape-adjustable member 430 switches from the first shape to the second shape, the shape of first solder paste 920A remains unchanged, remaining disc-shaped with a thickness of T1. When shape-adjustable member 430 is in the first shape, a portion of the middle of second solder paste 920B is occupied by shape-adjustable member 430, resulting in a discontinuous state. After shape-adjustable member 430 switches from the first shape to the second shape, the shape-adjustable member 430 withdraws, allowing second solder paste 920B to self-level and form a complete disc with a thickness of T2. T2 is less than T1.

[0061] By providing the vibration generator 20 , the flow of solder paste can be accelerated.

[0062] Unloading area Z4. See Figure 1 and Figure 2 The unloading assembly 80 includes a second conveyor, a seventh drive member, and a second clamp. The second clamp is disposed at the driving end of the seventh drive member. The seventh drive member is capable of driving the second clamp to move in three dimensions. The second clamp is used to grasp or release an object. The unloading assembly 80 may be described with reference to the loading assembly 50 described above.

[0063] The seventh drive element drives the second gripper 530 to transfer the printed template 40 from the unloading area Z4 to the carrier 30 in the loading area Z1. The seventh drive element then drives the second gripper to remove the carrier 30 (carrying the BGA chip) from the vibration generator 20 and transfer it to the second conveyor. The second conveyor is used to transport the carrier 30 from the unloading area Z4 to the next process.

[0064] In some embodiments, the shape-adjustable member 430 is made of a shape-memory metal. Within a first predetermined temperature range, the shape-adjustable member 430 assumes a first shape. Within a second predetermined temperature range, the shape-adjustable member 430 assumes a second shape. The temperature within the second predetermined temperature range is greater than the temperature within the first predetermined temperature range. The first shape-switching member 740 is configured to heat the shape-adjustable member 430 to maintain its temperature within the second predetermined temperature range. In some embodiments, the shape-adjustable member 430 is integrally formed with the mesh plate 420, which facilitates manufacturing.

[0065] In some embodiments, the first shape-switching member 740 includes a laser generator configured to emit a laser beam and irradiate the shape-variable member 430 to heat the shape-variable member 430. The fourth driver 710, the fifth driver 720, and the sixth driver 730 cooperate with each other to adjust the angle of the laser light emitted by the laser generator.

[0066] In some embodiments, the unloading assembly 80 further includes a second shape-switching element (not shown) configured to drive the shape-variable element 430 from the second shape to the first shape. In embodiments where the shape-variable element 430 achieves shape change through temperature changes, the second shape-switching element includes a fan configured to blow air toward the shape-variable element 430 to cool it. While the shape-variable element 430 can naturally cool to switch to the second shape, the fan accelerates the cooling process, thereby improving production efficiency. The second shape-switching element may be located in the first clamping jaw 530. In the unloading area Z4, after the printing template 40 on the carrier 30 is grasped by the first clamping jaw 530 of the loading assembly 50, the second shape-switching element (e.g., the fan) is activated to drive the shape-variable element 430 from the second shape to the first shape, preparing for the next printing cycle.

[0067] Refer to the following Figure 1 and Figure 2 , introducing the complete workflow of the printing device.

[0068] In the loading area Z1 , the loading assembly 50 installs the carrier 30 (carrying the BGA chip) transferred from the previous process onto the vibration generator 20 , and removes the printed template 40 from the carrier 30 in the unloading area Z4 and installs it onto the carrier 30 in the loading area Z1 .

[0069] In the printing zone Z2 , the scraper assembly 60 prints solder paste onto the pad 910 , wherein the shape-variable member 430 in the printing template 40 is in the first shape.

[0070] In the reduced thickness area Z3 , the first shape switching member 740 drives the shape variable member 430 to switch to the second shape, and the vibration generator 20 applies high-frequency vibration to the carrier 30 .

[0071] In the unloading area Z4 , after the loading assembly 50 removes the printing template 40 from the carrier 30 , the unloading assembly 80 removes the carrier 30 from the vibration generator 20 and transfers it to the next process.

[0072] See also Figure 18 . Figure 18 This is a flow chart of the automatic solder paste printing method for BGA chips of this application.

[0073] The automatic solder paste printing method for BGA chips includes the following steps: S101: When the shape-adjustable member is in a first shape, scraping solder paste on the stencil with a scraper so that the solder paste leaks through the holes in the stencil onto the pads of the BGA chip, thereby forming a solder paste body on the pads. The holes penetrate the stencil in a thickness direction. When in the first shape, at least a portion of the shape-adjustable member is located in the holes. S102: The shape-variable member is driven to switch from the first shape to the second shape by the first shape-switching member, so that the solder paste can self-level and fill the gap formed at the shape-variable member, thereby reducing the thickness of the solder paste. In the second shape, the shape-variable member is located outside the hole.

[0074] The above steps are merely provided to help understand the method, structure, and core concept of the present application. A person skilled in the art may make several improvements and modifications to the present application without departing from the principles of the present application, and such improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A BGA chip automatic solder paste printing device, characterized in that: include: A mesh plate (420), wherein the mesh plate (420) is provided with holes (421) penetrating in a thickness direction thereof; a shape-variable member (430), the shape-variable member (430) being selectively capable of being in a first shape and a second shape, wherein in the first shape, at least a portion of the shape-variable member (430) is located in the hole (421), and in the second shape, the shape-variable member (430) is located outside the hole (421); a scraper (630), the scraper (630) being used to scrape the solder paste on the stencil (420) when the shape-variable member (430) is in the first shape, so that the solder paste leaks through the hole (421) onto the solder pad (910) of the BGA chip, thereby forming a solder paste body (920) on the solder pad (910); A first shape switching member (740) is used to drive the shape-changing member (430) to switch from the first shape to the second shape, so that the solder paste (920) can self-level and fill the gap formed at the shape-changing member (430), thereby reducing the thickness of the solder paste (920).

2. The BGA chip automatic solder paste printing device according to claim 1, characterized in that: The shape-variable member (430) is connected to the edge of the hole (421). In the first shape, the shape-variable member (430) protrudes from the edge of the hole (421) toward the center area of the hole (421) and is entirely located in the hole (421). In the second shape, the shape-variable member (430) is located on the side of the mesh plate (420) that is away from the pad (910) in the thickness direction.

3. The BGA chip automatic solder paste printing device according to claim 2, characterized in that: In the first shape, in the thickness direction of the mesh plate (420), the shape-variable member (430) does not protrude from the surface of the mesh plate (420) on the side facing away from the pad (910).

4. The BGA chip automatic solder paste printing device according to claim 2, characterized in that: The shape-variable member (430) comprises: A first portion (431), wherein the first portion (431) is in a closed ring shape and is surrounded by a gap (433); a second portion (432), the second portion (432) being connected between an edge of the hole (421) and the first portion (431); Wherein, in the first shape, the notch (433) passes through the first portion (431) in the thickness direction of the mesh plate (420).

5. The BGA chip automatic solder paste printing device according to claim 1, characterized in that: The shape-changing member (430) is made of shape memory metal. Within a first predetermined temperature range, the shape-changing member (430) is in the first shape. Within a second predetermined temperature range, the shape-changing member (430) is in the second shape. The temperature value within the second predetermined temperature range is greater than the temperature value within the first predetermined temperature range. The first shape switching member (740) is used to heat the shape-changing member (430) so that the temperature of the shape-changing member (430) is within the second predetermined temperature range.

6. The BGA chip automatic solder paste printing device according to claim 5, characterized in that: The first shape switching member (740) includes a laser generator, which is used to emit a laser beam and irradiate the shape-changing member (430) to heat the shape-changing member (430).

7. The BGA chip automatic solder paste printing device according to claim 1, characterized in that: Also includes: A second shape switching member is provided, wherein the second shape switching member is used to drive the shape-changing member (430) to switch from the second shape to the first shape.

8. The BGA chip automatic solder paste printing device according to claim 7, characterized in that: The shape-changing member (430) is made of shape memory metal. Within a first predetermined temperature range, the shape-changing member (430) is in the first shape. Within a second predetermined temperature range, the shape-changing member (430) is in the second shape. The temperature value within the second predetermined temperature range is greater than the temperature value within the first predetermined temperature range. The second shape switching member is used to cool the shape-changing member (430) so that the temperature of the shape-changing member (430) is within the first predetermined temperature range.

9. The BGA chip automatic solder paste printing device according to claim 8, characterized in that: The second shape-switching member includes a fan, and the fan is used to blow airflow toward the shape-changing member (430) to cool the shape-changing member (430).

10. The BGA chip automatic solder paste printing device according to claim 1, characterized in that: Also includes: A vibration generator (20) is used to apply high-frequency vibration to the BGA chip to promote the self-leveling of the solder paste (920).

11. The automatic solder paste printing device for BGA chips according to any one of claims 1 to 10, characterized in that: Also includes: A turntable (10), the turntable (10) being rotatably arranged and used to carry the BGA chip, with a first working area and a second working area being arranged at intervals in the circumferential direction of the turntable (10); Wherein, there are multiple stencils (420), and the multiple stencils (420) are respectively arranged on the turntable (10) and arranged at circumferential intervals on the turntable (10). When one stencil (420) is located in the first working area, another stencil (420) is located in the second working area. There are multiple shape-variable members (430), and the multiple shape-variable members (430) are respectively arranged on the turntable (10). Each stencil (420) is correspondingly provided with a predetermined number of shape-variable members (430). The scraper (630) is arranged in the first working area, and the scraper (630) is used to scrape the solder paste on the stencil (420) located in the first working area. The first shape switching member (740) is arranged in the second working area, and the first shape switching member (740) is used to drive the shape-variable member (430) located in the second working area to switch from the first shape to the second shape.

12. The BGA chip automatic solder paste printing device according to claim 11, characterized in that: Also includes: A plurality of carriers (30), wherein the plurality of carriers (30) are detachably arranged on the turntable (10) and are arranged at intervals in the circumferential direction of the turntable (10); when one carrier (30) is located in the first working area, another carrier (30) is located in the second working area; the carrier (30) is used to carry the BGA chip and the stencil (420); the BGA chip and the stencil (420) are respectively arranged on the turntable (10) through the carriers (30); The mesh plates (420) correspond to the carriers (30) in a one-to-one manner, and each mesh plate (420) is arranged on the corresponding carrier (30).

13. A BGA chip automatic solder paste printing method, characterized in that: The steps include: When the shape-adjustable member is in a first shape, the scraper scrapes the solder paste on the stencil so that the solder paste leaks through the holes in the stencil onto the pads of the BGA chip, thereby forming a solder paste body on the pads. The holes penetrate the stencil in the thickness direction of the stencil. When in the first shape, at least a portion of the shape-adjustable member is located in the holes. The shape-variable member is driven by the first shape switching member to switch from the first shape to the second shape, so that the solder paste can self-level and fill the gap formed at the shape-variable member, thereby reducing the thickness of the solder paste. In the second shape, the shape-variable member is located outside the hole.

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