Flip chip mounting process

Abstract

To provide a flip chip mounting process that is effectively simplified and greatly improves production efficiency.SOLUTION: A process includes steps of: providing a plurality of chips with a plurality of conductive bumps; providing a plurality of circuit boards corresponding to a respective conductive bump and on which pads are respectively disposed; inverting and aligning the respective chips; transporting the respective chips and the respective circuit boards to a batch reflow furnace and performing a metal welding operation to produce a plurality of flip chip structures; embedding a liquid material in the respective circuit boards so as to cover an object to be cleaned; placing a flip chip structure in a chamber and heating; and intermittently increasing and decreasing the pressure and vacuum of the gas in the chamber with a pressure increasing and decreasing device and / or a vacuum generator, thereby causing the object to be cleaned from the circuit board by frictional cleaning provided by the greater energy generated by the wavy pulsations of the liquid material due to a change in the wave pulsations of the gas.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the technical field of flip chips, and more particularly to a flip chip mounting process in which a batch reflow oven is used to simultaneously heat, melt, and cool a large number of aligned chips and circuit boards for a predetermined period of time to complete a metal welding operation, and a liquid material is added and the liquid material is driven by a wavy airflow accompanied by intermittent pressure increases and decreases, causing friction or stirring effects, thereby improving residue cleaning efficiency, effectively simplifying the flip chip mounting process, and greatly improving production efficiency. [Background technology]

[0002] In an era of rapid advances in science and technology, new high-tech electronics are emerging, leading to the continuous introduction of user-friendly and functional electronic products, and a trend toward designs that are lighter, thinner, shorter, and smaller. To achieve these requirements, electronic components must meet a wide range of demands, including higher speed, multi-functionality, integration, compactness, and lower cost. As a result, integrated circuit packaging technology is also moving toward smaller size and higher density. Among various packaging technologies, flip chip packages (F / C packages) and other high-density stacked circuit packaging technologies that use bumps or solder balls for electrical connections are gradually becoming the mainstream for high-density packaging because they can shorten wiring length and increase signal transmission speed.

[0003] Conventional flip-chip mounting processes often require adhesives to bond materials. In particular, for metal bonding, some adhesives typically have high acid content and are corrosive in order to remove the dense oxide layer that forms on the bonding surface. However, the corrosive nature of these adhesives can seriously affect the performance of microelectronic devices. Therefore, a cleaning process is required to remove the adhesive or the reaction residue between the adhesive and the metal oxide remaining on the bonding surface. Some adhesives may leave behind organic matter after use, leaving an oily ester layer on the bonding surface. This cleaning process is necessary to avoid subsequent reliability issues for semiconductor components. However, as circuit boards become denser, the protrusions on the circuit board used for bonding become smaller, and the gap between the circuit board and the pads becomes narrower, removing these residues becomes increasingly difficult. If the corrosive adhesive remaining on the circuit board or on the bonding surface is not completely removed, the reliability of the components will be significantly reduced. Furthermore, the current common method of using cleaning solvents to clean these residues needs improvement because they can have an environmental impact if not handled properly.

[0004] Therefore, how to develop a packaging process that is more practical and economical in order to overcome the problems existing in the conventional flip chip mounting process is the goal and direction for the related industry to actively research, develop and break through.

[0005] In view of this, the inventor has developed the present invention, which is certainly practical, after detailed design and careful evaluation of the above-mentioned goals, based on his many years of experience in the manufacturing, development and design of related products. Summary of the Invention

[0006] (Problem to be solved by the invention) Traditional flip-chip mounting processes often require adhesives to bond materials. Particularly in the case of metal bonding, some adhesives typically have high acid content and are corrosive to remove the dense oxide layer that forms on the bonding surface. However, the corrosive nature of these adhesives can seriously affect the performance of microelectronic devices. Therefore, a cleaning process is required to remove the adhesive or the reaction residue between the adhesive and the metal oxide left on the bonding surface. However, as circuit boards become denser, the protrusions on the circuit board used for bonding become smaller, and the gap between the circuit board and the pad becomes narrower, removing these residues becomes increasingly difficult, requiring improvements.

[0007] (Technical means to solve the problem) To improve the above problem, the present invention provides a flip chip mounting process including the following steps: a. Providing a plurality of chips having an active surface and a plurality of conductive bumps formed on said active surface, said conductive bumps being at least one of tin, silver, copper, gold, indium, lead, bismuth, zinc, nickel, or other weld-friendly material; b. Providing a plurality of circuit boards each having a support surface with pads disposed on the support surface corresponding to each conductive bump;

[0008] c. Flux is applied to the surface of each of the pads, and the chips are flipped over and aligned so that the active surface of each of the chips faces the support surface of each of the circuit boards. The aligned chips and circuit boards are then transported to a batch reflow oven, where the conductive bumps are connected to the pads via the flux, and a metal welding operation is performed, so that each of the chips is electrically and structurally connected to the pads of each of the circuit boards via the conductive bumps, forming multiple flip chip structures that can transmit signals between the circuit boards and the chips.

[0009] d. A liquid material is embedded between each of the circuit boards and each of the chips so as to cover the object to be cleaned on each of the circuit boards.

[0010] e. Each of the flip chip structures containing the liquid material is placed in a chamber, and the chamber is heated to a predetermined temperature ranging from at least 25 to 200°C depending on the viscosity of the liquid material to increase the fluidity of the liquid material.

[0011] f. By intermittently evacuating the gas in the chamber with a vacuum generator, the maximum value is 1 atmosphere pressure or less and the minimum value is 10 -5 A wavy airflow is generated, which is a wavy change under a vacuum that fluctuates intermittently within the atmospheric pressure range, and the liquid material undergoes wavy changes due to the wavy change in the vacuum suction force of the gas, and the liquid material in contact with the object to be cleaned undergoes friction cleaning brought about by the greater energy generated by the wavy change, thereby more effectively removing the object to be cleaned that has adhered to each of the circuit boards from the circuit boards and the liquid material, achieving effects that cannot be achieved with conventional solution cleaning.

[0012] The present invention further provides a flip-chip mounting process, which includes the following steps: a. Providing a plurality of chips having an active surface and a plurality of conductive bumps formed on said active surface, said conductive bumps being at least one of tin, silver, copper, gold, indium, lead, bismuth, zinc, nickel, or other weld-friendly material; b. Providing a plurality of circuit boards each having a support surface with pads disposed on the support surface corresponding to each conductive bump;

[0013] c. Flux is applied to the surface of each of the pads, and the chips are flipped over and aligned so that the active surface of each of the chips faces the support surface of each of the circuit boards. The aligned chips and circuit boards are then transported to a batch reflow oven, where the conductive bumps are connected to the pads via the flux, and a metal welding operation is performed, so that each of the chips is electrically and structurally connected to the pads of each of the circuit boards via the conductive bumps, forming multiple flip chip structures that can transmit signals between the circuit boards and the chips.

[0014] d. A liquid material is embedded between each of the circuit boards and each of the chips so as to cover the object to be cleaned on each of the circuit boards.

[0015] e. Each of the flip chip structures containing the liquid material is placed in a chamber, and the chamber is heated to a predetermined temperature ranging from at least 25 to 200°C depending on the viscosity of the liquid material to increase the fluidity of the liquid material.

[0016] f. The gas in the chamber is intermittently increased or decreased in pressure and vacuum using an increase / decrease device and a vacuum generator, so that the maximum value is 50 atmospheric pressure or less and the minimum value is 10 -5 A wavy airflow is generated, which is a wavy change from high pressure to vacuum that fluctuates intermittently within the atmospheric pressure range, and the liquid material undergoes changes in wave shape due to the changes in the wave shape of the gas, and the liquid material in contact with the objects to be cleaned is subjected to frictional cleaning brought about by the greater energy generated by the wave shape change, thereby more effectively removing the objects to be cleaned that are attached to each of the circuit boards from the circuit boards and the liquid material, achieving effects that cannot be achieved with conventional solution cleaning.

[0017] The present invention further provides a flip-chip mounting process, which includes the following steps: a. Providing a plurality of chips having an active surface and a plurality of conductive bumps formed on said active surface, said conductive bumps being at least one of tin, silver, copper, gold, indium, lead, bismuth, zinc, nickel, or other weld-friendly material; b. Providing a plurality of circuit boards each having a support surface with pads disposed on the support surface corresponding to each conductive bump;

[0018] c. Flux is applied to the surface of each of the pads, and the chips are flipped over and aligned so that the active surface of each of the chips faces the support surface of each of the circuit boards. The aligned chips and circuit boards are then transported to a batch reflow oven, where the conductive bumps are connected to the pads via the flux, and a metal welding operation is performed, so that each of the chips is electrically and structurally connected to the pads of each of the circuit boards via the conductive bumps, forming multiple flip chip structures that can transmit signals between the circuit boards and the chips.

[0019] d. A liquid material is embedded between each of the circuit boards and each of the chips so as to cover the object to be cleaned on each of the circuit boards.

[0020] e. Each of the flip chip structures containing the liquid material is placed in a chamber, and the chamber is heated to a predetermined temperature ranging from at least 25 to 200°C depending on the viscosity of the liquid material to increase the fluidity of the liquid material.

[0021] f. By intermittently increasing or decreasing the pressure of the gas in the chamber using an intensifying or depressurizing device, a wavy airflow is generated that fluctuates intermittently from high pressure to 1 atmosphere, with a maximum value of 50 atmospheres or less and a minimum value of 1 atmosphere, and the liquid material undergoes wavy changes due to the changes in the gas wavy changes, and the liquid material in contact with the objects to be cleaned more effectively removes the objects to be cleaned attached to each of the circuit boards from each of the circuit boards and the liquid material due to friction cleaning brought about by the greater energy generated by the wavy changes, achieving effects that cannot be achieved with conventional solution cleaning.

[0022] The present invention further provides a flip-chip mounting process, which includes the following steps: a. Providing a plurality of chips having an active surface and a plurality of conductive bumps formed on said active surface, said conductive bumps being at least one of tin, silver, copper, gold, indium, lead, bismuth, zinc, nickel, or other weld-friendly material; b. Providing a plurality of circuit boards each having a support surface with pads disposed on the support surface corresponding to each conductive bump;

[0023] c. Flux is applied to the surface of each of the pads, and the chips are flipped over and aligned so that the active surface of each of the chips faces the support surface of each of the circuit boards. The aligned chips and circuit boards are then transported to a batch reflow oven, where the conductive bumps are connected to the pads via the flux, and a metal welding operation is performed, so that each of the chips is electrically and structurally connected to the pads of each of the circuit boards via the conductive bumps, forming multiple flip chip structures that can transmit signals between the circuit boards and the chips.

[0024] d. A liquid material is embedded between each of the circuit boards and each of the chips so as to cover the object to be cleaned on each of the circuit boards.

[0025] e. Each of the flip chip structures containing the liquid material is placed in a chamber, and the chamber is heated to a predetermined temperature ranging from at least 25 to 200°C depending on the viscosity of the liquid material to increase the fluidity of the liquid material.

[0026] f. A pressure booster is used to generate a gas pressure in the chamber ranging from a maximum of 50 atmospheres or less to a minimum of 1 atmosphere, from greater than 1 atmosphere up to at least a predetermined stable pressure, and physical dissolution occurs when the embedded liquid material comes into contact with the objects to be cleaned, causing the objects to be cleaned attached to each of the circuit boards to dissolve in the liquid material, and the diffusion force due to the predetermined temperature and concentration gradient after dissolution causes the objects to diffuse into the liquid material and separate from each of the circuit boards and liquid material, achieving an effect that cannot be achieved with conventional solution cleaning.

[0027] The circuit board may be at least one of a printed circuit board, an organic substrate, a glass substrate, a metal substrate, a lead frame, a wafer, a silicon interposer, and a package.

[0028] The flux is applied to the surface of each pad, and the application method includes spraying, spreading, and coating.

[0029] The flux used is a liquid flux, and the viscosity of the liquid flux ranges from 1 cps (centipoises) to 1000 Pa·s.

[0030] The cleaning target is flux, flux residue, oil ester, photolithography or manufacturing process product.

[0031] Among them, the liquid material is a base adhesive, which contains hard particles. The hard particles roll along with the wave-like movement of the base adhesive, enhancing the friction and cleaning effect of the hard particles, which is useful for cleaning the substances to be removed.

[0032] The base adhesive is an epoxy resin mixed with a filler such as silicon dioxide (SiO2) powder.

[0033] The aligned chips and circuit boards are transported into a batch reflow furnace, and the transporting means includes manual transport or transporting by an automatic transport device.

[0034] Then, the aligned chips and circuit boards are transported by manual transport.

[0035] The automatic transport device includes at least one transport vehicle and at least one cassette, and each of the aligned chips and each of the aligned circuit boards is stored in at least one of the cassettes, and each of the aligned chips and each of the aligned circuit boards is transported by at least one of the transport vehicles.

[0036] The transport vehicles include overhead cranes (OHTs), automated guided vehicles (AGVs), autonomous mobile robots (AMRs), and track-mounted automated guided vehicles (RGVs).

[0037] (Technical Effects) The flip chip mounting process of the present invention uses a batch-type reflow oven to perform a metal welding process by simultaneously heating, melting, and cooling a large number of aligned chips and circuit boards sequentially for a relatively long period of time. Furthermore, the liquid material controls the wave-like fluctuation of gas in the chamber to cause a wave-like fluctuation, generating a wave-like wave-like friction cleaning effect, or, similar to the accelerated dissolution of sugar in water by stirring, the liquid material dissolves the target material in the liquid material. The liquid material in contact with the target material generates greater energy due to the wave-like fluctuation, resulting in friction cleaning, which removes the target material attached to the circuit board from the circuit board. This improves residue cleaning efficiency, effectively simplifies the flip chip mounting process, and significantly improves production efficiency. Alternatively, gas at least at a predetermined pressure is supplied to dissolve the target material in the liquid material, and the target material is removed from the circuit board by the diffusion principle. In addition, by heating the temperature inside the chamber to 25 to 200°C, the moisture adsorbed inside the oil ester, some of the objects to be cleaned, or circuit boards will evaporate due to the heat, generating gas. This will cause the liquid material to undergo wave-like changes in the gas due to the wave-like changes under vacuum, from high pressure to 1 atmosphere, or from high pressure to vacuum, which can promote dissolution and diffusion between materials under high pressure environments, or even expel gas from the liquid material.

[0038] The above-mentioned objects, structures and features of the present invention will be more clearly understood after the technology, means and effects of the present invention are described in detail with reference to preferred embodiments and drawings. [Brief explanation of the drawings]

[0039] [Figure 1] FIG. 1 is a flow chart of a flip-chip mounting process according to one embodiment of the present invention. [Figure 2] FIG. 2 is a flow chart of a flip-chip mounting process according to another embodiment of the present invention. [Figure 3]FIG. 3 is a flow chart of a flip-chip mounting process according to another embodiment of the present invention. [Figure 4] FIG. 4 is a flow chart of a flip-chip mounting process according to another embodiment of the present invention. [Figure 5A] FIG. 5A is a schematic cross-sectional view of the flip-chip mounting process of FIGS. [Figure 5B] FIG. 5B is a schematic cross-sectional view of the flip-chip mounting process of FIGS. [Figure 5C] FIG. 5C is a schematic cross-sectional view of the flip-chip mounting process of FIGS. [Figure 5D] FIG. 5D is a schematic cross-sectional view of the flip-chip mounting process of FIGS. [Figure 5E] Fig. 5E is a schematic cross-sectional view of the flip chip mounting process of Fig. 1 to Fig. 4. Note that the schematic cross-sectional view shows a cross-sectional view of a single flip chip mounting process as an example, but a schematic cross-sectional view of a multiple flip chip mounting process can be inferred. DETAILED DESCRIPTION OF THE INVENTION

[0040] As shown in Figures 1 and 5A to 5E, Figure 1 is a flowchart of a flip chip mounting process according to one embodiment of the present invention, and Figures 5A to 5E are schematic cross-sectional views of the flip chip mounting process, and the present invention provides a flip chip mounting process including the following steps: a. (Step 21a) Providing a plurality of chips 310, each chip 310 having an active surface 311, and having a plurality of conductive bumps 320 (shown in FIG. 5A) on the active surface 311, the conductive bumps 320 being solder bumps made by a conventional bumping process and having a composition of at least one of tin, silver, copper, gold, indium, lead, bismuth, zinc, nickel, or other welding-friendly materials.

[0041] b. (Step 22a) A plurality of circuit boards 330 are prepared, each of which has a support surface 331, and pads 332 (shown in FIG. 5B) arranged on the support surface 331 in correspondence with each conductive bump 320.

[0042] c. (Step 23a) Flux is applied to the surface of each pad 332, and each chip 310 is inverted and aligned so that the active surface 311 of each chip 310 faces the support surface 331 of each circuit board 330. The aligned chips and circuit boards are then transported to a batch reflow oven, where the conductive bumps 320 are bonded to the pads 332 (shown in FIG. 5C) via the flux, and a metal welding operation is performed, so that each chip 310 is electrically and structurally connected to the pads 332 of each circuit board 330 via the conductive bumps 320. By manufacturing multiple flip-chip structures 300, signals can be transmitted between the circuit board 330 and the chip 310. The metal welding performed here refers to metal welding between the aligned chip 310 and circuit board 331, or between each conductive bump 320 and each pad 332, to bond each conductive bump 310 in a molten or semi-molten state to each pad 310 on the support surface 332 of the circuit board 320.

[0043] d. (Step 24a) A liquid material 410 is embedded between each circuit board 330 and each chip 310 so as to cover the cleaning target of each circuit board (shown in FIG. 5D).

[0044] e. (Step 25a) Each flip chip structure 300 containing the liquid material 410 is placed in a chamber 510 (shown in FIG. 5E), and the chamber 510 is heated to at least a predetermined temperature to enhance the fluidity of the liquid material, the predetermined temperature being between 25 and 200°C depending on the viscosity of the liquid material.

[0045] f. (Step 26a) The gas in the chamber 510 is intermittently evacuated with a vacuum generator (not shown) to a maximum pressure of 1 atmosphere or less and a minimum pressure of 10 -5A wavy airflow is generated, which is a wavy change under a vacuum that fluctuates intermittently within the atmospheric pressure range, and the liquid material 410 changes in wavy change due to the change in the wavy change of the vacuum suction force of the gas, and further, the liquid material 410 present on each chip 310 and each circuit board 330 is pulled by the mutual capillary force and the surface tension of the liquid material 410, so the liquid material 410 does not overflow even when a larger wavy change occurs. The liquid material 410 in contact with the object to be cleaned can be more effectively removed from each circuit board 330 and liquid material 410 due to frictional cleaning brought about by the larger energy generated by the wavy change, achieving an effect that cannot be achieved with conventional solution cleaning. Furthermore, the wavy motion of the liquid material 410 is pulled by the wavy motion of the gas, reducing direct energy transfer and reducing damage to the living body or scattering of the liquid material 410 due to excessive wavy motion.

[0046] The viscosity of the liquid flux ranges from 1 cps (centipoises) to 1000 Pa·s.

[0047] The cleaning targets include flux, flux residue, oil esters, and products from photolithography or manufacturing processes.

[0048] Among them, the liquid material 410 is a base adhesive, which contains hard particles. The hard particles roll along with the wave-like changes of the base adhesive, enhancing the friction and cleaning effect of the hard particles, which is useful for cleaning the material to be removed.

[0049] The base adhesive component is an epoxy resin mixed with fillers such as silicon dioxide (SiO2) powder.

[0050] The aligned chips 310 and circuit boards 330 are then transported, and the transporting means includes manual transport or transport by an automatic transport device.

[0051] The aligned chips 310 and circuit boards 330 are then manually transported.

[0052] The automatic transport device includes at least one transport vehicle and at least one cassette, and each aligned chip 310 and each aligned circuit board 330 is stored in at least one cassette, and each aligned chip 310 and each aligned circuit board 330 is transported by at least one of the transport vehicles.

[0053] Guided vehicles include overhead cranes (OHTs), automated guided vehicles (AGVs), autonomous mobile robots (AMRs) and track-mounted automated guided vehicles (RGVs).

[0054] As shown in Figures 2 and 5A to 5E, Figure 2 is a flowchart of a flip chip mounting process according to another embodiment of the present invention, and Figures 5A to 5E are schematic cross-sectional views of the flip chip mounting process, and the present invention provides a flip chip mounting process including the following steps: a. (Step 21b) Providing a plurality of chips 310, each chip 310 having an active surface 311, and having a plurality of conductive bumps 320 (shown in FIG. 5A) on the active surface 311, the conductive bumps 320 being solder bumps made by a conventional bumping process and having a composition of at least one of tin, silver, copper, gold, indium, lead, bismuth, zinc, nickel, or other welding-friendly materials.

[0055] b. (Step 22b) A plurality of circuit boards 330 are prepared, each of which has a support surface 331, and pads 332 (shown in FIG. 5B) arranged on the support surface 331 in correspondence with each conductive bump 320.

[0056] c. (Step 23b) Flux is applied to the surface of each pad 332, and each chip 310 is inverted and aligned so that the active surface 311 of each chip 310 faces the support surface 331 of each circuit board 330. The aligned chips and circuit boards are then transported to a batch reflow oven, where the conductive bumps 320 are bonded to the pads 332 (shown in FIG. 5C) via the flux, and a metal welding operation is performed, so that each chip 310 is electrically and structurally connected to the pads 332 of each circuit board 330 via the conductive bumps 320. By manufacturing multiple flip-chip structures 300, signals can be transmitted between the circuit board 330 and the chip 310. The metal welding performed here refers to metal welding between the aligned chip 310 and circuit board 331, or between each conductive bump 320 and each pad 332, to bond each conductive bump 310 in a molten or semi-molten state to each pad 310 on the support surface 332 of the circuit board 320.

[0057] d. (Step 24b) A liquid material 410 is embedded between each circuit board 330 and each chip 310 so as to cover the cleaning target of each circuit board (shown in FIG. 5D).

[0058] e. (Step 25b) Each flip chip structure 300 containing the liquid material 410 is placed in a chamber 510 (shown in FIG. 5E), and the chamber 510 is heated to at least a predetermined temperature to enhance the fluidity of the liquid material, the predetermined temperature being between 25 and 200°C depending on the viscosity of the liquid material.

[0059] f. (Step 26b) The gas in the chamber 510 is intermittently increased or decreased in pressure and evacuated using an increase / decrease device (not shown) and a vacuum generator (not shown) to achieve a maximum pressure of 50 atmospheres or less and a minimum pressure of 10 -5A wavy airflow is generated, which is a wavy change from high pressure to vacuum that fluctuates intermittently within the atmospheric pressure range, and the liquid material 410 changes in wave shape due to the change in the gas wave shape. Furthermore, the liquid material 410 present on each chip 310 and each circuit board 330 is pulled by the mutual capillary force and the surface tension of the liquid material 410, so the liquid material 410 does not overflow even when a larger wave shape occurs. Furthermore, the liquid material 410 in contact with the object to be cleaned can be more effectively removed from each circuit board 330 and the liquid material 410 due to frictional cleaning brought about by the larger energy generated by the wave shape change, achieving effects that cannot be achieved with conventional solution cleaning. Furthermore, the wavy motion of the liquid material 410 is pulled by the wavy motion of the gas, reducing direct energy transfer and reducing damage to the living body or scattering of the liquid material 410 due to excessive wavy motion.

[0060] The viscosity of the liquid flux ranges from 1 cps (centipoises) to 1000 Pa·s.

[0061] The cleaning targets include flux, flux residue, oil esters, and products from photolithography or manufacturing processes.

[0062] Among them, the liquid material 410 is a base adhesive, which contains hard particles. The hard particles roll along with the wave-like changes of the base adhesive, enhancing the friction and cleaning effect of the hard particles, which is useful for cleaning the material to be removed.

[0063] The base adhesive component is an epoxy resin mixed with fillers such as silicon dioxide (SiO2) powder.

[0064] The aligned chips 310 and circuit boards 330 are then transported, and the transporting means includes manual transport or transport by an automatic transport device.

[0065] The aligned chips 310 and circuit boards 330 are then manually transported.

[0066] The automatic transport device includes at least one transport vehicle and at least one cassette, and each aligned chip 310 and each aligned circuit board 330 is stored in at least one cassette, and each aligned chip 310 and each aligned circuit board 330 is transported by at least one of the transport vehicles.

[0067] Guided vehicles include overhead cranes (OHTs), automated guided vehicles (AGVs), autonomous mobile robots (AMRs) and track-mounted automated guided vehicles (RGVs).

[0068] As shown in Figures 3 and 5A to 5E, Figure 3 is a flowchart of a flip chip mounting process according to another embodiment of the present invention, and Figures 5A to 5E are schematic cross-sectional views of the flip chip mounting process, and the present invention provides a flip chip mounting process including the following steps: a. (Step 21c) Providing a plurality of chips 310, each chip 310 having an active surface 311, and having a plurality of conductive bumps 320 (shown in FIG. 5A) on the active surface 311, the conductive bumps 320 being solder bumps made by a conventional bumping process and having a composition of at least one of tin, silver, copper, gold, indium, lead, bismuth, zinc, nickel, or other welding-friendly materials.

[0069] b. (Step 22c) A plurality of circuit boards 330 are prepared, each of which has a support surface 331, and pads 332 (shown in FIG. 5B) arranged on the support surface 331 in correspondence with each conductive bump 320.

[0070] c. (Step 23c) Flux is applied to the surface of each pad 332, and each chip 310 is inverted and aligned so that the active surface 311 of each chip 310 faces the support surface 331 of each circuit board 330. The aligned chips and circuit boards are then transported to a batch reflow oven, where the conductive bumps 320 are bonded to the pads 332 (shown in FIG. 5C) via the flux, and a metal welding operation is performed, so that each chip 310 is electrically and structurally connected to the pads 332 of each circuit board 330 via the conductive bumps 320. By manufacturing multiple flip-chip structures 300, signals can be transmitted between the circuit board 330 and the chip 310. The metal welding performed here refers to metal welding between the aligned chip 310 and circuit board 331, or between each conductive bump 320 and each pad 332, to bond each conductive bump 310 in a molten or semi-molten state to each pad 310 on the support surface 332 of the circuit board 320.

[0071] d. (Step 24c) A liquid material 410 is embedded between each circuit board 330 and each chip 310 so as to cover the cleaning target of each circuit board (shown in FIG. 5D).

[0072] e. (Step 25c) Each flip chip structure 300 containing the liquid material 410 is placed in a chamber 510 (shown in FIG. 5E), and the chamber 510 is heated to at least a predetermined temperature to enhance the fluidity of the liquid material, the predetermined temperature being between 25 and 200°C depending on the viscosity of the liquid material.

[0073] f. (Step 26c) The gas pressure in chamber 510 is intermittently increased or decreased using an intensifying / depressurizing device (not shown), generating a wavy airflow that intermittently fluctuates from high pressure to 1 atmosphere, with a maximum value of 50 atmospheres or less and a minimum value of 1 atmosphere. The liquid material 410 changes in wave shape due to the change in the gas wave shape. Furthermore, the liquid material 410 present on each chip 310 and each circuit board 330 is pulled by the capillary force between them and the surface tension of the liquid material 410, so the liquid material 410 does not overflow even when larger wave shapes occur. Furthermore, the liquid material 410 in contact with the object to be cleaned can be more effectively removed from each circuit board 330 and liquid material 410 due to frictional cleaning brought about by the greater energy generated by the wave shape change, achieving effects not achievable with conventional solution cleaning. Furthermore, the wavy motion of the liquid material is pulled by the wavy motion of the gas, reducing direct energy transfer and reducing damage to the living body or scattering of the liquid material 410 due to excessive wavy motion.

[0074] The viscosity of the liquid flux ranges from 1 cps (centipoises) to 1000 Pa·s.

[0075] The cleaning targets include flux, flux residue, oil esters, and products from photolithography or manufacturing processes.

[0076] Among them, the liquid material 410 is a base adhesive, which contains hard particles. The hard particles roll along with the wave-like changes of the base adhesive, enhancing the friction and cleaning effect of the hard particles, which is useful for cleaning the material to be removed.

[0077] The base adhesive component is an epoxy resin mixed with fillers such as silicon dioxide (SiO2) powder.

[0078] The aligned chips 310 and circuit boards 330 are then transported, and the transporting means includes manual transport or transport by an automatic transport device.

[0079] The aligned chips 310 and circuit boards 330 are then manually transported.

[0080] The automatic transport device includes at least one transport vehicle and at least one cassette, and each aligned chip 310 and each aligned circuit board 330 is stored in at least one cassette, and each aligned chip 310 and each aligned circuit board 330 is transported by at least one of the transport vehicles.

[0081] Guided vehicles include overhead cranes (OHTs), automated guided vehicles (AGVs), autonomous mobile robots (AMRs) and track-mounted automated guided vehicles (RGVs).

[0082] As shown in Figures 4 and 5A to 5E, Figure 4 is a flowchart of a flip chip mounting process according to another embodiment of the present invention, and Figures 5A to 5E are schematic cross-sectional views of the flip chip mounting process, and the present invention provides a flip chip mounting process including the following steps: a. (Step 21d) Providing a plurality of chips 310, each chip 310 having an active surface 311, and a plurality of conductive bumps 320 (shown in FIG. 5A) on the active surface 311, the conductive bumps 320 being solder bumps made by a conventional bumping process and having a composition of at least one of tin, silver, copper, gold, indium, lead, bismuth, zinc, nickel, or other welding-friendly materials.

[0083] b. (Step 22d) A plurality of circuit boards 330 are prepared, each of which has a support surface 331, and pads 332 (shown in FIG. 5B) arranged on the support surface 331 in correspondence with each conductive bump 320.

[0084] c. (Step 23d) Flux is applied to the surface of each pad 332, and each chip 310 is inverted and aligned so that the active surface 311 of each chip 310 faces the support surface 331 of each circuit board 330. The aligned chips and circuit boards are then transported to a batch reflow oven, where the conductive bumps 320 are bonded to the pads 332 (shown in FIG. 5C) via the flux, and a metal welding operation is performed, so that each chip 310 is electrically and structurally connected to the pads 332 of each circuit board 330 via the conductive bumps 320. By manufacturing multiple flip-chip structures 300, signals can be transmitted between the circuit board 330 and the chip 310. The metal welding performed here refers to metal welding between the aligned chip 310 and circuit board 331, or between each conductive bump 320 and each pad 332, to bond each conductive bump 310 in a molten or semi-molten state to each pad 310 on the support surface 332 of the circuit board 320.

[0085] d. (Step 24d) A liquid material 410 is embedded between each circuit board 330 and each chip 310 so as to cover the cleaning target of each circuit board (shown in FIG. 5D).

[0086] e. (Step 25d) Each flip chip structure 300 containing the liquid material 410 is placed in a chamber 510 (shown in FIG. 5E), and the chamber 510 is heated to at least a predetermined temperature to enhance the fluidity of the liquid material, the predetermined temperature being between 25 and 200°C depending on the viscosity of the liquid material.

[0087] f. (Step 26d) A pressure booster (not shown) is used to generate a predetermined pressure within the chamber 510, with a maximum value of 50 atmospheres or less and a minimum value of 1 atmosphere. The physical dissolution generated by contact between the embedded liquid material 410 and the objects to be cleaned causes the objects to be cleaned attached to each circuit board 330 to dissolve into the liquid material 410. The diffusion force due to the predetermined temperature and the concentration gradient after dissolution removes the objects to be cleaned attached to each circuit board 330 from each circuit board 330 and the liquid material 410, achieving effects that cannot be achieved with conventional solution cleaning.

[0088] The viscosity of the liquid flux ranges from 1 cps (centipoises) to 1000 Pa·s.

[0089] The cleaning targets include flux, flux residue, oil esters, and products from photolithography or manufacturing processes.

[0090] Among them, the liquid material 410 is a base adhesive, which contains hard particles. The hard particles roll along with the wave-like changes of the base adhesive, enhancing the friction and cleaning effect of the hard particles, which is useful for cleaning the material to be removed.

[0091] The base adhesive component is an epoxy resin mixed with fillers such as silicon dioxide (SiO2) powder.

[0092] The aligned chips 310 and circuit boards 330 are then transported, and the transporting means includes manual transport or transport by an automatic transport device.

[0093] The aligned chips 310 and circuit boards 330 are then manually transported.

[0094] The automatic transport device includes at least one transport vehicle and at least one cassette, and each aligned chip 310 and each aligned circuit board 330 is stored in at least one cassette, and each aligned chip 310 and each aligned circuit board 330 is transported by at least one of the transport vehicles.

[0095] Guided vehicles include overhead cranes (OHTs), automated guided vehicles (AGVs), autonomous mobile robots (AMRs) and track-mounted automated guided vehicles (RGVs).

[0096] Although the preferred embodiments of the present invention have been specifically described above as the technical features of the present invention, those skilled in the art in this field may change or modify the present invention without departing from the spirit and principles of the present invention, and such changes or modifications shall fall within the scope of the claims as defined below. [Explanation of symbols]

[0097] 21a-26a steps 21b-26b steps 21c-26c steps 21d-26d steps 300 flip chip structure 310 chips 311 Active Surface 320 Conductive Bump 330 Circuit Board 331 Support surface 332 Pad 410 Liquid materials 510 Chamber

Claims

1. a. providing a plurality of chips having an active surface with a plurality of conductive bumps disposed on the active surface; b. providing a plurality of circuit boards having a support surface with pads disposed on the support surface corresponding to each conductive bump; c) applying flux to the surface of each of the pads, flipping each of the chips and aligning the active surface of each of the chips to face the support surface of each of the circuit boards, and then transferring the aligned chips and each of the circuit boards to a batch reflow oven, where the conductive bumps are connected to the pads via the flux, and a metal welding operation is performed, so that each of the chips is electrically and structurally connected to each of the pads of each of the circuit boards via the conductive bumps, thereby forming a plurality of flip chip structures capable of transmitting signals between the circuit boards and the chips; d. A liquid material is embedded between each of the circuit boards and each of the chips so as to cover the object to be cleaned on each of the circuit boards; e. placing each of the flip chip structures containing the liquid material in a chamber, and heating the chamber to a predetermined temperature ranging from at least 25 to 200°C depending on the viscosity of the liquid material to enhance the flowability of the liquid material; f. By intermittently evacuating the gas in the chamber with a vacuum generator, the maximum value is 1 atmosphere pressure or less and the minimum value is 10 －５ generating a wavy airflow that is a wavy change under a vacuum that fluctuates intermittently in the atmospheric pressure range, causing the liquid material to change in wavy change due to the wavy change in the vacuum suction force of the gas, and the liquid material in contact with the object to be cleaned more effectively removes the object to be cleaned attached to each of the circuit boards from each of the circuit boards and the liquid material by friction cleaning brought about by the greater energy generated by the wavy change.

2. a. providing a plurality of chips having an active surface with a plurality of conductive bumps disposed on the active surface; b. providing a plurality of circuit boards having a support surface with pads disposed on the support surface corresponding to each conductive bump; c) applying flux to the surface of each of the pads, flipping each of the chips and aligning the active surface of each of the chips to face the support surface of each of the circuit boards, and then transferring the aligned chips and each of the circuit boards to a batch reflow oven, where the conductive bumps are connected to the pads via the flux, and a metal welding operation is performed, so that each of the chips is electrically and structurally connected to each of the pads of each of the circuit boards via the conductive bumps, thereby forming a plurality of flip chip structures capable of transmitting signals between the circuit boards and the chips; d. A liquid material is embedded between each of the circuit boards and each of the chips so as to cover the object to be cleaned on each of the circuit boards; e. placing each of the flip chip structures containing the liquid material in a chamber, and heating the chamber to a predetermined temperature ranging from at least 25 to 200°C depending on the viscosity of the liquid material to enhance the flowability of the liquid material; f. By intermittently increasing and decreasing the pressure of the gas in the chamber and evacuating it with a pressure increasing / decreasing device and a vacuum generator, the maximum value is 50 atmospheric pressure or less and the minimum value is 10 －５ generating a wavy airflow that is a wavy change from high pressure to vacuum that fluctuates intermittently within the atmospheric pressure range, and causing the liquid material to undergo a change in wavy change due to the change in the wavy change of the gas, so that the liquid material in contact with the object to be cleaned more effectively removes the object to be cleaned attached to each of the circuit boards from each of the circuit boards and the liquid material by friction cleaning brought about by the greater energy generated by the wavy change.

3. a. providing a plurality of chips having an active surface with a plurality of conductive bumps disposed on the active surface; b. providing a plurality of circuit boards having a support surface with pads disposed on the support surface corresponding to each conductive bump; c) applying flux to the surface of each of the pads, flipping each of the chips and aligning the active surface of each of the chips to face the support surface of each of the circuit boards, and then transferring the aligned chips and each of the circuit boards to a batch reflow oven, where the conductive bumps are connected to the pads via the flux, and a metal welding operation is performed, so that each of the chips is electrically and structurally connected to each of the pads of each of the circuit boards via the conductive bumps, thereby forming a plurality of flip chip structures capable of transmitting signals between the circuit boards and the chips; d. A liquid material is embedded between each of the circuit boards and each of the chips so as to cover the object to be cleaned on each of the circuit boards; e. placing each of the flip chip structures containing the liquid material in a chamber, and heating the chamber to a predetermined temperature ranging from at least 25 to 200°C depending on the viscosity of the liquid material to enhance the flowability of the liquid material; a pressure increase / decrease device for increasing / decreasing the pressure of the gas in the chamber intermittently to generate a wavy airflow that varies intermittently from a high pressure to 1 atmosphere with a maximum value of 50 atmospheres or less and a minimum value of 1 atmosphere, the liquid material undergoing wavy fluctuations due to the change in the wavy fluctuation of the gas causes the liquid material in contact with the objects to be cleaned to more effectively remove the objects attached to each of the circuit boards from each of the circuit boards and the liquid material by frictional cleaning brought about by the greater energy generated by the wavy fluctuation.

4. a. providing a plurality of chips having an active surface with a plurality of conductive bumps disposed on the active surface; b. providing a plurality of circuit boards having a support surface with pads disposed on the support surface corresponding to each conductive bump; c) applying flux to the surface of each of the pads, flipping each of the chips and aligning the active surface of each of the chips to face the support surface of each of the circuit boards, and then transferring the aligned chips and each of the circuit boards to a batch reflow oven, where the conductive bumps are connected to the pads via the flux, and a metal welding operation is performed, so that each of the chips is electrically and structurally connected to each of the pads of each of the circuit boards via the conductive bumps, thereby forming a plurality of flip chip structures capable of transmitting signals between the circuit boards and the chips; d. A liquid material is embedded between each of the circuit boards and each of the chips so as to cover the object to be cleaned on each of the circuit boards; e. placing each of the flip chip structures containing the liquid material in a chamber, and heating the chamber to a predetermined temperature ranging from at least 25 to 200°C depending on the viscosity of the liquid material to enhance the flowability of the liquid material; a pressure booster for the gas in the chamber to generate a predetermined pressure of at least 50 atmospheres at maximum and 1 atmosphere at minimum, dissolving the objects to be cleaned attached to each of the circuit boards into the liquid material by physical dissolution generated upon contact between the embedded liquid material and the objects to be cleaned, and separating each of the objects to be cleaned attached to the circuit boards from the liquid material by a diffusion force due to the predetermined temperature and a concentration gradient after dissolution.

5. 5. The flip chip mounting process according to claim 1, 2, 3 or 4, wherein the flux is a liquid flux, and the viscosity of the liquid flux ranges from 1 centipoise (cps) to 1000 Pa·s.

6. 5. The flip chip mounting process according to claim 1, wherein the object to be cleaned is a flux, flux residue, oil ester, or product of a photolithography or manufacturing process.

7. The flip chip mounting process according to claim 1, 2, 3 or 4, characterized in that the liquid material is a base adhesive, the base adhesive contains hard particles, and the hard particles roll along with the wave-like deformation of the base adhesive, thereby enhancing the friction and cleaning effect of the hard particles and helping to clean the material to be removed.

8. 8. The flip chip mounting process according to claim 7, wherein the base adhesive is an epoxy resin.

9. 5. The flip chip mounting process according to claim 1, further comprising the step of transferring the aligned chips and circuit boards using an automatic transfer device.

10. 10. The flip chip mounting process of claim 9, wherein the automatic transport device includes at least one transport vehicle and at least one cassette, and each of the aligned chips and each of the aligned circuit boards is stored in at least one of the cassettes, and each of the aligned chips and each of the aligned circuit boards is transported by at least one of the transport vehicles.

11. 11. The flip chip mounting process of claim 10, wherein the transport vehicle includes an overhead traveling crane (OHT), an automated guided vehicle (AGV), an autonomous mobile robot (AMR), and a track-mounted automated guided vehicle (RGV).

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