Method for forming solder contact pins

Abstract

A plurality of solder contact pins are formed on the contact pad layout of the substrate. [Solution] The contact pad layout comprises a plurality of contact pads (5), and the method includes the steps of: a) arranging a plurality of first solder balls (2) at a plurality of placement positions of the placement layout of a transfer tool (1); b) positioning the transfer tool (1) facing a substrate (6) so that the plurality of first solder balls (2) are associated with the plurality of contact pads (5); c) positioning the plurality of first solder balls (2) on the plurality of contact pads (5); and d) melting the plurality of first solder balls (2) and releasing the plurality of first solder balls (2) from the transfer tool (1) onto the plurality of contact pads (5) so as to form a plurality of solder bumps (2a) on the plurality of contact pads (5).

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE

[0001] The present disclosure relates to a method for forming a plurality of solder contact pins on a contact pad layout of a substrate, the contact pad layout comprising a plurality of contact pads.

[0002]

[0002] Conventionally, soldering points in the form of solder contact pins are formed on a substrate by positioning solder contact pins having a specific geometric shape, i.e., a specific height and diameter, on the substrate. In particular, the solder contact pins are positioned on the substrate using a mask having openings corresponding to the shape of the solder contact pins and a vibration method to align the solder contact pins within the openings and on the substrate. The solder contact pins are then connected to the substrate using a heat convection or heat conduction process, such as a reflow oven, via a conductive adhesive or soldering material, preferably having a lower melting point than the solder contact pins.

[0003] In this way, solder contact pins of the size required for a specific application, such as connecting a chip or another substrate, can be positioned on the substrate and attached to the substrate. However, there is a disadvantage in that, depending on the application, specific sizes of solder contact pins and corresponding sizes of holders and masks must be used to supply and position the solder contact pins on the substrate. If another substrate is to be connected to the solder contact pins, the other substrate must be provided with a conductive adhesive or soldering material having a lower melting point. Furthermore, the use of different materials for the substrate, contact medium, and contact pin material can lead to contact surface problems.

[0004]

[0004] Document DE 19838532 A1 discloses a method and a device for positioning and melting a plurality of solder balls on a substrate using a template device with a perforated disk. The solder balls are either provided in the internal space of the device and ejected through the template openings of the device using overpressure (Figures 2 to 6), or the solder balls are sucked from the outside of the device into the template openings using negative pressure in the internal space of the device, and then ejected onto the substrate by creating overpressure in the internal space (Figures 8 to 11). The solder balls positioned on the substrate are melted to the substrate by applying laser energy onto the solder balls.

[0005] German Patent Application Publication No. 19739481 discloses a method for positioning a plurality of solder balls on a substrate and fusing the plurality of solder balls on the substrate with a laser. Specifically, the method of German Patent Application Publication No. 19739481 includes the steps of: sucking a plurality of solder balls from a solder ball reservoir through a plurality of passages in a solder ball fixing device, each passage having a cross-sectional area smaller than the cross-sectional area of ​​the solder ball, so that each solder ball is fixed in the passage; moving the solder ball fixing device to the substrate and positioning the solder balls on the surface of the substrate; and melting the solder balls by transmitting a laser pulse through the passages. In particular, a vacuum pump generates a negative pressure in the cavity of the solder ball fixing device to suck the solder balls and fix them in the passages. While the solder balls are being sucked into the passages, it is possible to check, for example, by pressurized air and / or a laser beam whether all of the solder balls are fixed in the passages. Additionally, the laser pulses are generated by a laser pulse generating means capable of transmitting the laser pulses through the individual glass fibers provided in each solder ball.

[0006]

[0006] Thus, by using the method disclosed in DE 198 38 532 A1 or DE 197 39 481 A1, multiple solder balls can be applied to a substrate in a time-saving manner without using flux. However, the methods known from the prior art are limited with regard to the production of soldering points of different sizes, in particular heights, required for certain joining applications, for example for the connection of certain electronic components, such as chips or other substrates.

[0007] Starting from the prior art, it is an object of the present disclosure to provide a method for forming a plurality of solder contact pins on a contact pad layout of a substrate, the method being simple and allowing the height of the solder contact pins to be variable, and a solder ball positioning apparatus for carrying out such a method.

[0008]

[0008] This object is solved by the methods according to independent claims 1 and 9. Preferred embodiments are the subject matter of the dependent claims.

[0009]

[0009] The present disclosure provides a method for forming a plurality of solder contact pins on a contact pad layout of a substrate, the contact pad layout comprising a plurality of contact pads, the method comprising: a) arranging a plurality of first solder balls at a plurality of placement locations on a placement layout of a transfer tool, the placement layout of the transfer tool corresponding to the contact pad layout of the substrate; b) positioning the transfer tool opposite the substrate such that the plurality of first solder balls are associated with the plurality of contact pads; c) positioning the plurality of first solder balls on the plurality of contact pads; and d) melting the plurality of first solder balls to form a plurality of solder bumps on the plurality of contact pads. a) releasing a plurality of solder balls from a transfer tool onto a plurality of contact pads; b) moving the transfer tool away from the substrate; c) placing a plurality of second solder balls at placement locations of a placement layout of the transfer tool; d) positioning the transfer tool facing the substrate such that the plurality of second solder balls are associated with a plurality of solder bumps; h) positioning the plurality of second solder balls on the plurality of solder bumps; i) melting the plurality of second solder balls and releasing the plurality of second solder balls from the transfer tool onto the plurality of solder bumps to form a plurality of monolithic solder contact pins, which may also be called solder pillars, on the plurality of contact pads; and j) moving the transfer tool away from the substrate.

[0010]

[0010] In steps a) and f), the step of placing a plurality of solder balls at a plurality of placement locations of the placement layout of the transfer tool may be performed by picking up the solder balls from a solder ball reservoir. Preferably, to pick up the solder balls from the solder ball reservoir, the solder ball reservoir is exposed to ultrasonic waves so as to, on the one hand, achieve a statistically uniform distribution density of the solder balls in the reservoir and, on the other hand, cause the solder balls to bounce up in response to the ultrasonic vibrations. The solder balls that bounce up and impact the transfer tool can be positioned and held at the placement location by, for example, applying a negative pressure to the placement location.

[0011]

[0011] In step d), the steps of melting the first solder balls and firing the first solder balls from the transfer tool onto the contact pads to form a plurality of solder bumps on the contact pads can be performed substantially simultaneously or in rapid succession. The same considerations apply to the steps of melting the second solder balls and firing the second solder balls from the transfer tool onto the solder bumps to form a plurality of monolithic solder contact pins on the contact pads in step i). It is only important that after melting the first solder balls and firing the first solder balls onto the contact pads, and after melting the second solder balls and firing the second solder balls onto the solder bumps, substantially vertical monolithic solder contact pins are formed on the substrate.

[0012] The above-described method can be used to quickly and easily form a large number of solder contact pins on a substrate. Because the solder contact pins are formed from a soldering material, there is no need to use a conductive adhesive or additional soldering material, for example, when an electrical component, such as a chip or another substrate, is attached to the substrate. Therefore, contact surface problems caused by using different materials for the substrate, contact medium, and contact pin material can be reduced. The above-described method can be performed without using flux, i.e., without applying flux to the contact pads on the substrate before melting the solder balls onto the contact pads.

[0013] In a further embodiment, steps f) through j) are repeatedly performed to increase the height of the monolithic solder contact pin.

[0014]

[0014] In this way, by repeating steps f) to j), solder contact pins with variable heights can be easily formed on a substrate.

[0015]

[0015] In a further embodiment, the last of the plurality of solder balls positioned on the monolithic solder contact pin has a lower melting point than the solder balls positioned below the last of the plurality of solder balls positioned.

[0016]

[0016] Therefore, when an electronic component, such as a chip or another substrate, is joined to a substrate using a heat convection or heat conduction process, such as a reflow oven, the component can be securely attached to the substrate via the solder contact pins while maintaining the stability of the solder contact pins and preventing the solder contact pins from collapsing during attachment. Specifically, depending on the application, solder balls of different materials or solder materials of different alloys can be used for each layer of solder balls in the solder contact pins.

[0017]

[0017] In a further embodiment, between steps a) and b) and / or between steps f) and g), it is checked whether all of the multiple placement locations of the placement layout are covered with solder balls by pressure reading of the dynamic pressure at the placement locations and / or by optically inspecting the placement locations.

[0018] In this way, it is possible to ensure that all placement locations on the transfer tool are covered with solder balls, thereby preventing defects from occurring when forming monolithic solder contact pins. Therefore, inspection helps to form multiple high-quality solder contact pins on the contact pad layout of the substrate. The inspection can be performed in any manner. For example, the inspection can be performed optically, for example, using a camera, or using a laser to scan the placement locations. If the transfer tool has multiple passages, each end of which has a solder ball placement location, thereby closing the passage when a solder ball is placed in the placement location, the dynamic pressure within each passage can be read or measured for each of the placement locations to check whether a solder ball has been placed in the respective placement location. Furthermore, in the latter case, checking whether the placement location is covered with solder balls can be performed by detecting the pressure within a vacuum chamber branching into the multiple passages leading to the placement locations.

[0019] In a further embodiment, in step a) or step f), the solder balls are placed by suction at a plurality of placement locations of a placement layout of the transfer tool.

[0020]

[0020] The transfer tool may include a plurality of passages having a cross-sectional area smaller than that of the solder balls, each passage having a placement position for the solder ball at one end and connected to a suction force generating device at the other end. The plurality of placement positions form a placement layout of the transfer tool. By generating negative pressure in the passages with the suction force generating device, the solder balls can be sucked to fixate them in the placement positions in the passages. By stopping the suction force generating device, the negative pressure is released, allowing the solder balls to be positioned on or released to contact pads or solder bumps on the substrate. Thus, suction is an easy way to reliably place solder balls in the placement positions of the placement layout of the transfer tool.

[0021] In a further embodiment, in step d) or step i), the solder balls are melted by applying laser energy onto the solder balls.

[0022]

[0022] Laser melting allows for precise control over the solder ball melting process. Furthermore, laser melting is a fast process, so the energy required to melt the solder ball can be introduced into the solder ball in the shortest possible time, particularly in the millisecond range, e.g., 5 ms to 50 ms, thereby keeping process speeds high. Furthermore, laser melting can be easily integrated into automated processes, improving efficiency and consistency.

[0023] In a further embodiment, the method includes measuring the height of the monolithic solder contact pin.

[0024]

[0024] Using the above-described method, a substrate having solder contact pins of variable heights can be formed by repeatedly melting solder balls onto contact pads or solder bumps. Although the height of the solder contact pins to be formed can generally be calculated in advance, in certain applications, information about the actual height of the fabricated solder contact pins is required, and therefore, measuring the actual height of the fabricated solder contact pins can increase the reliability of the process.

[0025] In a further embodiment, the step of measuring the height of the monolithic solder contact pin is performed optically and / or by force reading.

[0026]

[0026] Optical measurement of the height of the solder contact pins, for example using a camera or laser, is preferred because it can be automated, is accurate, and is fast. Alternatively or additionally, the height of the solder contact pins may be determined by measuring or reading the contact force between the transfer tool and the solder contact pins. The contact force correlates with the axial movement of the transfer tool toward the substrate, and therefore the resulting contact force when the transfer tool contacts the solder contact pins indicates the height of the solder contact pins.

[0027]

[0027] The present disclosure provides a solder ball positioning apparatus comprising a transfer tool, a laser source, a suction force generating device, and a controller, wherein the controller performs the following steps: a) using the suction force generating device to position a plurality of first solder balls at a plurality of placement locations on a placement layout of the transfer tool, the placement layout of the transfer tool corresponding to a contact pad layout of a substrate, the contact pad layout comprising a plurality of contact pads; b) positioning the transfer tool facing the substrate such that the plurality of first solder balls are associated with the plurality of contact pads; c) positioning the plurality of first solder balls on the plurality of contact pads; and d) melting the plurality of first solder balls using the laser source to form a plurality of solder bumps on the plurality of contact pads, and removing the plurality of first solder balls from the transfer tool. a plurality of solder balls on the plurality of solder bumps; and a transfer tool, a laser source, and a suction force generating device for controlling the transfer tool to perform a method that may include: a) releasing the plurality of second solder balls onto a plurality of contact pads; b) moving the transfer tool away from the substrate; c) using a suction force generating device to place the plurality of second solder balls at placement positions of a placement layout of the transfer tool; d) positioning the transfer tool against the substrate such that the plurality of second solder balls are associated with a plurality of solder bumps; h) positioning the plurality of second solder balls on the plurality of solder bumps; i) using a laser source to melt the plurality of second solder balls and release the plurality of second solder balls from the transfer tool onto the plurality of solder bumps to form a plurality of monolithic solder contact pins on the plurality of contact pads; and j) moving the transfer tool away from the substrate.

[0028]

[0028] The transfer tool may include a plurality of passages having a cross-sectional area smaller than that of the solder balls, each passage having a placement position for the solder ball at one end and connected to a suction force generating device at the other end. The plurality of placement positions form a placement layout of the transfer tool. By generating negative pressure in the passages with the suction force generating device, the solder balls can be attracted to the passages at the placement positions and fixed to the passages. By deactivating the suction force generating device, the negative pressure is released, allowing the solder balls to be placed on or released to contact pads or solder bumps on the substrate.

[0029]

[0029] In steps a) and f), the step of placing a plurality of solder balls at a plurality of placement locations of the placement layout of the transfer tool may be performed by picking up the solder balls from a solder ball reservoir. Preferably, to pick up the solder balls from the solder ball reservoir, the solder ball reservoir is exposed to ultrasonic waves so as to, on the one hand, achieve a statistically uniform distribution density of the solder balls in the reservoir and, on the other hand, cause the solder balls to bounce up in response to the ultrasonic vibrations. The solder balls that bounce up and impact the transfer tool can be positioned and held at the placement location by, for example, applying a negative pressure to the placement location.

[0030]

[0030] In step d), the steps of melting a plurality of first solder balls by using a laser source and firing the plurality of first solder balls from a transfer tool onto the plurality of contact pads to form a plurality of solder bumps on the plurality of contact pads can be performed substantially simultaneously or in rapid succession. The same considerations apply to the steps of melting a plurality of second solder balls by using a laser source and firing the plurality of second solder balls from a transfer tool onto the plurality of solder bumps to form a plurality of monolithic solder contact pins on the plurality of contact pads in step i). It is only important that after melting the first solder balls and firing the first solder balls onto the contact pads, and after melting the second solder balls and firing the second solder balls onto the solder bumps, substantially vertical monolithic solder contact pins are formed on the substrate.

[0031]

[0031] The above-described solder ball positioning device can be used to quickly and easily form a large number of solder contact pins on a substrate. Because the solder contact pins are formed from a soldering material, there is no need to use a conductive adhesive or additional soldering material when, for example, an electrical component, such as a chip or another substrate, is attached to the substrate. Therefore, contact surface problems caused by using different materials for the substrate, contact medium, and contact pin material can be reduced.

[0032]

[0032] The present disclosure provides a controller for a solder ball positioning apparatus comprising a transfer tool, a laser source, and a suction force generating device, wherein the controller performs the following steps: a) using the suction force generating device to position a plurality of first solder balls at a plurality of placement locations on a placement layout of the transfer tool, the placement layout of the transfer tool corresponding to a contact pad layout of a substrate, the contact pad layout comprising a plurality of contact pads; b) positioning the transfer tool facing the substrate such that the plurality of first solder balls are associated with the plurality of contact pads; c) positioning the plurality of first solder balls on the plurality of contact pads; and d) melting the plurality of first solder balls using the laser source to form a plurality of solder bumps on the plurality of contact pads, and transferring the plurality of first solder balls to the transfer tool. a transfer tool, a laser source, and a suction force generating device to perform a method that may include: e) releasing a plurality of second solder balls from a transfer tool onto a plurality of contact pads; f) using a suction force generating device to place the plurality of second solder balls at placement locations of a placement layout of the transfer tool; g) positioning the transfer tool against the substrate such that the plurality of second solder balls are associated with a plurality of solder bumps; h) positioning the plurality of second solder balls on the plurality of solder bumps; i) melting the plurality of second solder balls by using a laser source and releasing the plurality of second solder balls from the transfer tool onto the plurality of solder bumps to form a plurality of monolithic solder contact pins on the plurality of contact pads; and j) removing the transfer tool from the substrate.

[0033] The transfer tool may include a plurality of passages having a cross-sectional area smaller than that of the solder ball, each passage having a placement position for the solder ball at one end and connected to a suction force generating device at the other end. The plurality of placement positions form a placement layout of the transfer tool. By controlling the suction force generating device by the controller to generate negative pressure in the passage, the solder ball can be sucked so that it is fixed to the passage at the placement position. By stopping the suction force generating device by the controller, the negative pressure is released, allowing the solder ball to be positioned on or released to a contact pad or solder bump on the substrate.

[0034]

[0034] In steps a) and f), the step of placing a plurality of solder balls at a plurality of placement locations of the placement layout of the transfer tool may be performed by picking up the solder balls from a solder ball reservoir. Preferably, to pick up the solder balls from the solder ball reservoir, the solder ball reservoir is exposed to ultrasonic waves so as to, on the one hand, achieve a statistically uniform distribution density of the solder balls in the reservoir and, on the other hand, cause the solder balls to bounce up in response to the ultrasonic vibrations. The solder balls that bounce up and impact the transfer tool can be positioned and held at the placement location by, for example, applying a negative pressure to the placement location.

[0035]

[0035] In step d), the steps of melting a plurality of first solder balls by using a laser source and firing the plurality of first solder balls from a transfer tool onto the plurality of contact pads to form a plurality of solder bumps on the plurality of contact pads can be performed substantially simultaneously or in rapid succession. The same considerations apply to the steps of melting a plurality of second solder balls by using a laser source and firing the plurality of second solder balls from a transfer tool onto the plurality of solder bumps to form a plurality of monolithic solder contact pins on the plurality of contact pads in step i). It is only important that after melting the first solder balls and firing the first solder balls onto the contact pads, and after melting the second solder balls and firing the second solder balls onto the solder bumps, substantially vertical monolithic solder contact pins are formed on the substrate.

[0036]

[0036] The above-described controller is useful for quickly and easily forming a large number of solder contact pins on a substrate. Because the solder contact pins are formed from a soldering material, there is no need to use a conductive adhesive or additional soldering material when attaching an electrical component, such as a chip or another substrate, to the substrate. Therefore, contact surface problems caused by using different materials for the substrate, contact medium, and contact pin material can be reduced. [Brief explanation of the drawings]

[0037]

[0037] An embodiment of the present disclosure will now be described with reference to several figures. [Figure 1] 1 illustrates a front view of a solder ball positioning device for forming solder contact pins on a contact pad layout of a substrate, the contact pad layout comprising a plurality of contact pads, according to one embodiment. [Figure 2]10 illustrates another front view of the solder ball positioning device of FIG. 1 adding solder balls to a contact pad layout of a substrate to form solder bumps on a plurality of contact pads. [Figure 3] 10 illustrates another front view of the solder ball positioning device of FIG. 1 applying solder balls to a contact pad layout of a substrate while the solder balls are in contact with the contact pads. [Figure 4] 3 shows a front view of the solder ball positioning device of FIG. 2 adding solder balls to solder bumps present on a substrate. [Figure 5] 3 illustrates another front view of the solder ball positioning device of FIG. 2 adding solder balls to solder bumps present on a substrate. [Figure 6] 3 shows a front view of a solder contact pin formed on the substrate of FIG. 2.

[0038]

[0038] The figures are merely schematic in nature and are intended solely for the purpose of understanding the present disclosure. The proportions of the elements shown in the figures have been appropriately adjusted to facilitate a better understanding of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0039]

[0039] Figure 1 discloses a solder ball positioning apparatus 10 according to one embodiment, comprising a movable conveying tool 1, a laser source 8, a suction force generating device (not shown), and a controller (not shown) configured to control the conveying tool 1, the laser source 8, and the suction force generating device.

[0040] 2-6 show a solder ball positioning apparatus 10 performing several steps of a method for forming a plurality of solder contact pins 7 on a contact pad layout of a substrate 6. FIG.

[0041] Specifically, the transfer tool 1 includes a plurality of passages 11 having a cross-sectional area smaller than that of the solder balls to be picked up by the transfer tool 1, each of which has a placement position for the solder ball at one end and is connected to a suction force generating device at the other end. The plurality of placement positions form a placement layout of the transfer tool 1. Note that FIGS. 1 to 5 each only exemplarily disclose six passages 11 or six placement positions in the placement layout. However, the placement layout may include more than six placement positions, i.e., the transfer tool 1 may include more than six passages 11 that may be placed as needed. By generating negative pressure in the passages 11 with the suction force generating device, the solder balls can be sucked to fix them in the placement positions.

[0042] As shown in FIG. 2, first solder balls 2 are picked up from a solder ball reservoir (not shown) by the transfer tool 1 and sucked by a suction force generating device so as to be fixed in the passage 11. Although not shown, it is checked whether all of the multiple placement positions of the placement layout are covered with solder balls. Next, the transfer tool 1 is positioned opposite a substrate 6 having multiple contact pads 5 arranged in a contact pad layout corresponding to the placement layout of the transfer tool 1. The multiple first solder balls 2 are positioned on the multiple contact pads 5 as shown in FIG. 3. Next, the laser source 8 is activated, so that a laser beam 9 emitted through the passage 11 melts the multiple first solder balls 2. By stopping the suction force generating device, the solder balls 2 are released onto the multiple contact pads 5 to form multiple solder bumps 2a (see FIG. 4) on the multiple contact pads 5.

[0043]

[0043] Next, the transfer tool 1 is pulled away from the substrate, and the suction force generating device is activated to pick up the second solder balls 3 from the solder ball reservoir, thereby arranging the second solder balls 3 at the arrangement positions of the arrangement layout of the transfer tool 1. The transfer tool 1 is positioned facing the substrate 6 so that the second solder balls 3 are associated with the solder bumps 2a, as shown in FIG. 4. The second solder balls 3 are positioned on the solder bumps 2a. The laser source 8 is then activated, so that the laser 9 emitted through the passage 11 melts the second solder balls 3. The suction force generating device is stopped, thereby releasing the solder balls 3 onto the solder bumps 2a.

[0044]

[0044] As shown in Figure 5, by repeating the above steps and melting additional solder balls 4 onto multiple solder bumps 2a, monolithic solder contact pins 7 of any height can be formed on the substrate 6, as shown in Figure 6.

[0045] The above-described solder ball positioning apparatus 10 and method can be used to quickly and easily form a large number of solder contact pins 7 on a substrate 6. Because the solder contact pins 7 are formed from a soldering material, there is no need to use a conductive adhesive or additional soldering material when an electrical component, such as a chip or another substrate, is attached to the substrate 6. Therefore, contact surface problems resulting from using different materials for the substrate, contact medium, and contact pin material can be reduced. [Explanation of symbols]

[0046]

[0046] 1...transport tool, 2...first solder ball, 2a...solder bump, 3...second solder ball, 4...further solder ball, 5...contact pad, 6...substrate, 7...solder contact pin, 8...laser source, 9...laser beam, 10...solder ball positioning device, 11...path

Claims

1. 1. A method for forming a plurality of solder contact pins (7) on a contact pad layout of a substrate (6), said contact pad layout comprising a plurality of contact pads (5), said method comprising: a) arranging a plurality of first solder balls (2) at a plurality of placement locations of a placement layout of a transfer tool (1), wherein the placement layout of the transfer tool (1) corresponds to the contact pad layout of the substrate (6); b) positioning the transfer tool (1) facing the substrate (6) so that the first solder balls (2) are associated with the contact pads (5); c) positioning the plurality of first solder balls (2) on the plurality of contact pads (5); d) melting the first solder balls (2) and releasing the first solder balls (2) from the transfer tool (1) onto the contact pads (5) to form solder bumps (2a) on the contact pads (5); e) separating the transfer tool (1) from the substrate (6); f) placing a plurality of second solder balls (3) at the placement locations of the placement layout of the transfer tool (1); g) positioning the transfer tool (1) facing the substrate (6) so that the plurality of second solder balls (3) are associated with the plurality of solder bumps (2a); h) positioning the plurality of second solder balls (3) on the plurality of solder bumps (2a); i) melting the second solder balls (3) and releasing the second solder balls (3) from the transfer tool (1) onto the solder bumps (2a) to form monolithic solder contact pins (7) on the contact pads (5); j) separating the transfer tool (1) from the substrate (6); A method comprising:

2. 2. The method of claim 1, wherein steps f) to j) are repeatedly performed to increase the height of the monolithic solder contact pin (7).

3. 3. The method of claim 2, wherein the last positioned solder balls on the monolithic solder contact pin (7) have a lower melting point than the solder balls positioned below the last positioned solder balls.

4. 2. The method of claim 1, wherein between steps a) and b) and / or between steps f) and g), it is checked whether all of the plurality of placement locations of the placement layout are covered with solder balls by pressure readings of dynamic pressure at the placement locations and / or by optically inspecting the placement locations.

5. 2. The method of claim 1, wherein in step a) or step f), the solder balls are placed at the plurality of placement locations of the placement layout of the transfer tool (1) by suction.

6. 2. The method of claim 1, wherein in step d) or step i), the solder balls are melted by applying laser energy onto the solder balls.

7. 2. The method of claim 1, further comprising the step of measuring the height of the monolithic solder contact pin (7).

8. 8. The method according to claim 7, wherein the step of measuring the height of the monolithic solder contact pin (7) is performed optically and / or by force reading.

9. A solder ball positioning apparatus (10) comprising a transfer tool (1), a laser source (8), a suction force generating device, and a controller, the controller: a) placing a plurality of first solder balls (2) at a plurality of placement positions of a placement layout of the transfer tool (1) by using the suction force generating device, wherein the placement layout of the transfer tool (1) corresponds to a contact pad layout of a substrate (6), and the contact pad layout comprises a plurality of contact pads (5); b) positioning the transfer tool (1) facing the substrate (6) so that the first solder balls (2) are associated with the contact pads (5); c) positioning the plurality of first solder balls (2) on the plurality of contact pads (5); d) melting the first solder balls (2) by using the laser source (8) and releasing the first solder balls (2) from the transfer tool (1) onto the contact pads (5) to form solder bumps (2a) on the contact pads (5); e) separating the transfer tool (1) from the substrate (6); f) placing a plurality of second solder balls (3) at the placement positions of the placement layout of the transfer tool (1) by using the suction force generating device; g) positioning the transfer tool (1) facing the substrate (6) so that the plurality of second solder balls (3) are associated with the plurality of solder bumps (2a); h) positioning the plurality of second solder balls (3) on the plurality of solder bumps (2a); i) using the laser source (8) to melt the second solder balls (3) and release the second solder balls (3) from the transfer tool (1) onto the solder bumps (2a) so as to form monolithic solder contact pins (7) on the contact pads (5); j) separating the transfer tool (1) from the substrate (6); a solder ball positioning apparatus (10) configured to control the transfer tool (1), the laser source (8), and the suction force generating device to perform a method comprising:

10. A controller for a solder ball positioning apparatus (10) comprising a transfer tool (1), a laser source (8), and a suction force generating device, the controller comprising: a) placing a plurality of first solder balls (2) at a plurality of placement positions of a placement layout of the transfer tool (1) by using the suction force generating device, wherein the placement layout of the transfer tool (1) corresponds to a contact pad layout of a substrate (6), and the contact pad layout comprises a plurality of contact pads (5); b) positioning the transfer tool (1) facing the substrate (6) so that the first solder balls (2) are associated with the contact pads (5); c) positioning the plurality of first solder balls (2) on the plurality of contact pads (5); d) melting the first solder balls (2) by using the laser source (8) and releasing the first solder balls (2) from the transfer tool (1) onto the contact pads (5) to form solder bumps (2a) on the contact pads (5); e) separating the transfer tool (1) from the substrate (6); f) placing a plurality of second solder balls (3) at the placement positions of the placement layout of the transfer tool (1) by using the suction force generating device; g) positioning the transfer tool (1) facing the substrate (6) so that the plurality of second solder balls (3) are associated with the plurality of solder bumps (2a); h) positioning the plurality of second solder balls (3) on the plurality of solder bumps (2a); i) using the laser source (8) to melt the second solder balls (3) and release the second solder balls (3) from the transfer tool (1) onto the solder bumps (2a) so as to form monolithic solder contact pins (7) on the contact pads (5); j) separating the transfer tool (1) from the substrate (6); a controller configured to control the transport tool (1), the laser source (8), and the suction force generating device to perform a method comprising:

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