US20060225851A1

US20060225851A1 - Chip washing apparatus

Info

Publication number: US20060225851A1
Application number: US11/099,646
Authority: US
Inventors: Hsien-Hsin Chiu
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-04-06
Filing date: 2005-04-06
Publication date: 2006-10-12

Abstract

A chip washing apparatus comprises an injection tube and a housing, wherein the injection tube includes a water inlet for importing a pressurized washing liquid and a water outlet connected to the housing. A bent bottom edge of the housing is inwardly bent to softly cover the surfaces of the chip and a substrate, which bonds to the chip. After the bent bottom edge of the housing softly covers the surfaces of the chip and the substrate, the pressured washing liquid is allowed to flow through the covered fine slits and gaps between die contacts. Accordingly, the residues between the bonded chip and substrate are removed by the pressured washing liquid.

Description

FIELD OF THE INVENTION

The present invention relates to a chip washing apparatus for removing residues on a chip of a printed circuit board, which are left after the bonding operation, and more particularly to a chip washing apparatus for removing the residues, for example, solder liquids on a flip chip with a multilayer connection.

BACKGROUND OF THE INVENTION

As shown in FIG. 1, a conventional chip 7 on a printed circuit board includes a plurality of bent pins 71 extended from the peripheral surface of the chip 7 for connecting with corresponding points on a connection board 72, wherein the pins 71 are exposed around the chip 7 and the chip 7 is transferred to a packaging apparatus to form a package 8. However, this kind of chip 7 is limited by the dimension of its peripheral surface so the pins 71 cannot be disposed in high density. Besides, for the pin type conduction, the conducting wires of the pins 71 require longer paths and cannot satisfy the increasingly rapid progress in transmission speed. Accordingly, a flip-chip technique is disclosed in response to the increased number of pins in the ultra-fine chip and electric devices so as to increase the transmission speed.
Referring further to FIG. 2, a flip-chip type chip 4 is directly bonded to a substrate by means of the flip-chip technique. A plurality of die contacts 42, for example, hundreds of matrix type dies, are arranged on the bottom surface 41 of the chip 4 in matrix for connecting with corresponding points on a top surface 51 of the substrate 5 and an adhesive 6 is formed around the chip 4. However, solder liquids or residues are remained between the bottom surface 41 of the chip 4 and the top surface 51 of the substrate and between die contacts when the die contacts 42 of the chip 4 are bonded to the corresponding points on the substrate 5. Moreover, after they are bonded, the bottom surface 41 of the chip 4 is practically at a distance, for example, about 0.08 mm, from the surrounding fine slits on the top surface 51 of the substrate 5, and the distances between these bonding contacts are very small. If a conventional washing liquid is sprayed, the washing liquid will be obstructed by the peripheral surface of the chip 4 and these bonding contacts and reflected to form a backflow so the flow of the washing liquid is obstructed and cannot remove the residues between the bonding contacts. Accordingly, the incomplete washing procedure cannot remove the residues. Because it takes time for dissolving the residues, an immersion washing procedure will waste too much time. Moreover, the washing liquid cannot flow into the fine slits to wash away the residues and the solder liquids so the immersion washing procedure is of no use. Besides, it wastes a lot of time and manpower for repeatedly immersing and washing the chip. Consequently, the conventional washing method always suffers from incomplete washing.

SUMMARY OF THE INVENTION

In view of the drawbacks of the prior art, the present inventor discloses a chip washing apparatus in accordance with the repeated experiments and professional experience in design and manufacture.
It is the main object of the present invention to provide a chip washing apparatus, wherein a pressurized washing liquid is applied to the covered chip and substrate so as to remove the residues completely.
It is another object of the present invention to provide the chip washing apparatus, wherein one side of the chip is covered and at least a half of fine slits and gaps are covered such that the pressurized washing liquid is allowed to remove the residual solder liquids or residues between the contacts and the pressurized washing liquid is drained out from the uncovered fine slits and gaps.
It is still another object of the present invention to provide the chip washing apparatus, wherein after the pressurized washing liquid is injected into the fine slits on the covered side of the chip, the previous uncovered side of the chip is covered and the pressurized washing liquid is applied again in a reverse direction to repeatedly perform the washing procedure, thereby cleaning the chip and draining out the residues completely.
It is still another object of the present invention to provide the chip washing apparatus, wherein the pressurized washing liquid flows through the fine slits between the chip and the substrate and is drained out from thereof so as to completely removing the residual solder liquids or residues.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-section view showing the chip of the prior art.
FIG. 2 is a schematic cross-section view showing the chip of the present invention.
FIG. 3 is a schematic view showing that the chips of the present invention are mounted sequentially.
FIG. 4 is a schematic view showing that the chips of the present invention are mounted in bulk.
FIG. 5 is a partial, enlarged cross-section view showing the present invention.
FIG. 6 is a cross-section view taken along the line 6-6 of FIG. 5 and viewed in the direction of arrow.
FIG. 7 is schematic top view of FIG. 5.
FIG. 8 is a schematic view showing that one side of the chip is covered and washed.
FIG. 9 is a lateral cross-section view of FIG. 8.
FIG. 10 is a schematic view showing that the other side of the chip is covered and washed.
FIG. 11 is a schematic top view of FIG. 10.
FIG. 12 is a schematic top view showing one preferred embodiment of the present invention.
FIG. 13 is a schematic top view showing another preferred embodiment of the present invention.
FIG. 14 is a schematic top view showing still another preferred embodiment of the present invention in which one side of the chip is covered and washed.
FIG. 15 is a schematic top view showing still another preferred embodiment of the present invention in which the other side of the chip is covered and washed.
FIG. 16 is a schematic top view showing still another preferred embodiment of the present invention.
FIG. 17 is a schematic view showing that one side of the chip is covered and washed in accordance with another preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
Referring to FIG. 2 through FIG. 7, a chip washing apparatus of the present invention comprises an injection tube 1 and a housing 2. The injection tube 1 includes a water inlet 11 for importing a pressurized washing liquid (not shown) and a water outlet 12 connected to the housing 2, wherein a bent bottom edge 21 of the housing 2 is bent inwardly corresponding to the shape of bonded substrate 5 and chip 4 so as to downwardly abut on or upwardly separate from the surfaces of the chip 4 and the substrate 5 for covering at least a half of the fine slits 3 between the chip 4 and the substrate 5.
Referring to FIG. 3, FIG. 4, FIG. 8, and FIG. 9, several chips 4 and several substrates 5, which bond to the chips 4, can be mounted in a mounting plate 9 sequentially or in bulk for being transported by a belt conveyer to perform the washing procedure in a stepping manner. In addition, these injection tubes 1 can jointly or separately ascend or descend and import the pressurized washing liquid to allow the bent bottom edge 21 of the housing 2 to lightly touch and cover the surfaces of the chip 4 and the substrate 5 (Because of its thinness and frailty the flip chip cannot abide the slightly large pressing force). After covering a predetermined surface area of the chip 4 and the substrate 5, the pressurized washing liquid is applied uniformly and softly to extend a bent tube 22 of the housing 2 and to allow the bent bottom edge 21 to cover the surfaces of the chip 4 and the substrate 5, thereby allowing the pressured washing liquid flows through the covered fine slits 31 and the gaps between the die contacts. In that case, the residual solder liquids or residues between the die contacts are removed by the pressured washing liquid and drained out from the uncovered fine slits 32 between the chip 4 and the substrate 5.
In addition to the aforementioned top-bottom washing method from top to bottom of the injection tubes 1, the chip 4 bonded to the surface of the substrate 5 can be immersed in the washing liquid with a liquid level over the chip 4, as shown in FIG. 17, wherein an external pumping apparatus is connected to the injection tube 1′ for generating a suction force to drain the pressurized washing liquid and allow it to uniformly flow through the covered fine slits 31 between the bonded chip 4 and substrate 5 and the gaps between the die contacts. In that case, the residual solder liquids or residues between the die contacts are washed by the pressured washing liquid and drained out from the water outlet 12′ via the water inlet 11′ of the injection tube 1′. Because of the suction force the bent bottom edge 301 below the bent tube 302 of the housing 30 is bent outwardly to prevent the housing 30 from being lifted up by the suction force.
As shown in FIG. 10, FIG. 11, and FIG. 12, after the pressurized washing liquid washes the fine slits 31 on one side of the chip 4 for a predetermined time period, the housing 2 is raised to separate the bent bottom edge 21 from the surfaces of the chip 4 and the substrate 5. Next, the mounting plate 9 is reversely moved to perform a reverse washing process. In other words, the uncovered fine slits 32 between the chip 4 and the substrate 5 and parts of the covered fine slits 31 in the previous washing process are covered by the bent bottom edge 21 of the housing 2 to expose little parts of the covered slits 31 in this washing process such that the pressurized washing liquid with a reverse flow direction can wash the bonding contacts of the chip 4 in a reverse direction and further wash the places where the residual solder liquids or residues might be still left so as to wash the chip 4 and remove the residues completely. After completely washing the chip 4, a purely clean cleaning liquid is sprayed on the chip 4. Thereafter, the chip 4 is dried to finish the process. In the present invention, several housings 2 may be sequentially applied to cover the chip 4 in multiple directions so as to remove the residues more completely.
FIG. 13 illustrates another preferred embodiment of the present invention, wherein the bent bottom edge 21′ of the housing 2 between the covered fine slits 31 and the uncovered fine slits 32 is slanted toward the uncovered fine slits 32 such that the uncovered fine slits 32 are capable of guiding the pressurized washing liquid to crossly wash the bonding contacts in the fine slits 3.
FIG. 14 and FIG. 15 illustrate still another preferred embodiment of the present invention, wherein a suction tube 23″, which is connected to a suction apparatus (not shown), is mounted beside the housing 2″. The bent tune 22″ of the housing 2″ is extended and the surfaces of the chip 4 and the substrate 5 are covered by the inwardly bent bottom edge 21″ such that the fine slits 32, which are not covered by the housing 2″, can increase the flow speed and the washing capability of the pressurized washing liquid and clean the solder liquids and the residues when the pressurized washing liquid flows through the fine slits 32.
FIG. 16 illustrates still another preferred embodiment of the present invention, wherein the housing 20 and the housing 20′ are coupled to one another and mounted to cover the chip 4 symmetrically, and each of them includes control valves for connecting to the pressurized washing liquid and the suction apparatus (not shown). Therefore, when the housing 20 is applied to import the pressurized washing liquid, the suction apparatus for sucking the pressurized washing liquid is conducted to the housing 20′. Alternatively, when the housing 20′ is applied to import the pressurized washing liquid, the suction apparatus is conducted to the housing 20 for increasing the flow speed of the pressurized washing liquid, which washes the chip 4. Accordingly, the efficiency for washing chip 4 is improved by repeated washing and suction processes.
To sum up, the chip washing apparatus of the present invention is composed of most simplified devices and the easiest procedures to allow the pressurized washing liquid to exactly flow through the gaps between the bonded substrate and chip, thereby rapidly and fully cleaning the residual solder liquids or residues. The completely cleaning result is obtained since the pressurized washing liquid will not be reflected by the surface of the chip to form the backflow that cannot flow into the gaps. Accordingly, the production cost of the chip washing apparatus is reduced, and the present invention is applicable to chips with different specifications. Consequently, the present invention complies with all requirements of patent rules and is submitted for a patent.
While the preferred embodiment of the invention has been set forth for the purpose of disclosure, modifications of the disclosed embodiment of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments, which do not depart from the spirit and scope of the invention.

Claims

1. A chip washing apparatus comprising

an injection tube having a water outlet and a water inlet for importing a pressurized washing liquid; and

a housing connected to the water outlet or the water inlet of the injection tube, a bent bottom edge of the housing being bent corresponding to the shape of the chip and a substrate bonded to the chip so as to cover at least a half of fine slits between the chip and the substrate when the bent bottom edge touches the chip, wherein after the pressurized washing liquid is uniformly applied for softly extending a bent tube of the housing and allowing the bent bottom edge to cover the surfaces of the chip and the substrate, the pressured washing liquid is allowed to flow through the covered fine slits and gaps between die contacts.

2. The chip washing apparatus of claim 1, wherein the chip and the substrate can be mounted in a mounting plate with another chip and another substrate, and the injection tubes can jointly ascend or descend and import the pressurized washing liquid such that the bent bottom edge of the housing is allowed to lightly touch and cover the surfaces of the chips and the substrates so as to perform a washing procedure.

3. The chip washing apparatus of claim 1, wherein the chip and the substrate can be mounted in a mounting plate with another chip and another substrate, and the injection tubes can separately ascend or descend and import the pressurized washing liquid such that the bent bottom edge of the housing is allowed to lightly touch and cover the surfaces of the chips and the substrates so as to perform a washing procedure.

4. The chip washing apparatus of claim 1, wherein after the pressurized washing liquid washes the fine slits on one side of the chip for a predetermined time period, the housing is raised to separate the bent bottom edge from the surfaces of the chip and the substrate, and thereafter the uncovered fine slits between the chip and the substrate and parts of the covered fine slits in the previous washing process are covered by the bent bottom edge of the housing to expose little parts of the covered fine slits such that the pressurized washing liquid can wash the chip in a reverse direction.

5. The chip washing apparatus of claim 1, wherein another housing is further applied to individually cover the chip in a different direction so as to allow the pressurized washing liquid to flow through and wash the fine slits between the chip and the substrate in a different direction.

6. The chip washing apparatus of claim 1, wherein the bent bottom edge of the housing between the covered fine slits and the uncovered fine slits is slanted toward the uncovered fine slits.

7. The chip washing apparatus of claim 1, wherein a suction tube is mounted beside the uncovered fine slits of the chip.

8. The chip washing apparatus of claim 1, wherein the housing and another housing are coupled to one another to symmetrically cover the surfaces of the chip and the substrate and each of them comprises control valves for connecting to the pressurized washing liquid and a suction apparatus.

9. The chip washing apparatus of claim 1, wherein the bent bottom edge of the housing is bent inwardly or outwardly.

10. The chip washing apparatus of claim 1, wherein the chip bonded to the surface of the substrate is immersed in the washing liquid with a liquid level over the chip, and an external pumping apparatus is connected to the injection tube for allowing the pressurized washing liquid to uniformly flow through the covered fine slits between the bonded chip and substrate.