Patent Application
20120103521
The present disclosure generally relates to the technology of manufacturing printed circuit boards (PCBs), and particularly, to an etching apparatus with suction mechanism.
In the manufacture of PCBs, PCB substrates may be fed through a series of processing machines via a conveyor system. The process includes resist stripping, pre-cleaning, etching, neutralizing, water rinsing, and drying. The pre-cleaning, etching, neutralizing, and water rinsing, are known as wet processing steps. In these wet processing steps, a spray system comprising at least one set of spray nozzles is arranged to face the conveyor system to spray wet processing liquid on the PCB substrates on the conveyor system. For example, the spray system can spray etchant on the PCB substrate to remove portions of a copper foil from the substrate, and then traces will be formed by the remaining portions of the copper foil.
During the etching process, portions of the copper foil react with etchant sprayed thereon to form small and shallow depressions. Etchant inevitably collects in the depressions and begins to react with the copper foil in the depressions. However, even after the reaction, such reacted etchant remains pooled in the depressions and prevents new or different etchant reacting with the copper foil in the depressions. If the copper foil in the depressions can be made immune to the etching procedure in this way, the configuration of the copper traces and the electrical properties of the manufactured PCBs are adversely affected.
What is needed, therefore, is an etching apparatus that overcomes the limitations described.
Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
Embodiments will now be described in detail with reference to the drawings.
Referring to
The conveyor 12 includes a number of upper conveying rollers 123, a number of lower conveying rollers 125, a number of upper supporting rollers 127, and a number of lower supporting rollers 129. The conveying rollers 123 and 125 are configured for conveying a PCB substrate positioned therebetween, the supporting rollers 127 and 129 are configured for supporting the substrate in between the rollers 123 and 125. The upper rollers 123 and 127 are positioned above the substrate and are in contact with the top surface of the substrate, and the lower rollers 125 and 129 are below and in contact with the bottom surface of the substrate. The rollers 123, 125, 127, and 129 are parallel with each other, and each is perpendicular to the direction of movement of the substrate.
The upper conveying rollers 123 constitute an upper conveying roller group 122, which includes a number of subgroups. Each of these subgroups is constituted by two adjacent juxtaposed upper conveying rollers 123, equidistantly arranged. The lower conveying rollers 125 constitute a lower conveying roller group 124, which is opposite to the upper conveying roller group 122. The lower conveying roller group 124 includes a number of subgroups equidistantly arranged. Each of these subgroups includes two adjacent juxtaposed lower conveying rollers 125. The upper supporting rollers 127 constitute an upper supporting roller group 126, and the lower supporting rollers 129 constitute a lower supporting roller group 128 opposite to the upper supporting roller group 126. The supporting rollers 127 and 129 are equally spaced. In the illustrated embodiment as shown in
Each upper conveying roller 123 includes an upper rotating shaft 1230 and a number of rotating wheels 1231 which are all mounted on the upper rotating shaft 1230 in line with each other along a lengthwise direction thereof. The central axis of the upper rotating shaft 1230 is coaxial with the central axes of the upper rotating wheels 1231. Each lower conveying roller 125 includes a lower rotating shaft 1250 and a number of lower rotating wheels 1251 which are all mounted on the lower rotating shaft 1250 in line with each other along a lengthwise direction thereof. The diameter of the upper rotating wheels 1231 is equal to that of the lower rotating wheels 1251, this distance may be, for example, about 30 millimeters. The supporting rollers 127 and 129 are solid cylindrical rollers with a diameter smaller than that of the rotating wheels 1231 and 1251.
The rollers 123, 125, 127, and 129 can be driven by one or more motors. The direction of rotation of the upper rotating shaft 1230 is the reverse to that of the lower rotating shaft 1250, and the linear velocity of the upper wheels 1231 is equal to that of the lower wheels 1251. The substrate positioned between the upper and lower wheels 1231 and 1251 can be moved along by the rotation of the wheels 1231 and 1251 at a predefined speed, at 3 meters per minute, for example. Similarly, the direction of rotation of the upper supporting rollers 127 is the reverse to that of the lower supporting rollers 129.
The conveyor 12 may function by means of other suitable mechanisms, for example, a motor driven belt or other mechanically driven bulk material handling device.
The spraying mechanism 14 includes an upper spraying system 140 and a lower spraying system 145. The upper spraying system 140 includes a first submersible pump 141, a first supplying pipe 142, a number of upper distributing pipes 143, and a number of upper spraying nozzles 144. The first submersible pump 141 is disposed in the tank 100, and is immersed in the etchant received in the tank 100. The first supplying pipe 142 includes a first channel 1421 and a second channel 1422 which is perpendicular to the first channel 1421. The first channel 1421 interconnects the first submersible pump 141 and the second channel 1422. The second channel 1422 communicates with each of the upper distributing pipes 143. The upper distributing pipes 143 are parallel with each other and are equidistantly arranged above the upper conveying roller group 122. The distance between any two adjacent upper distributing pipes 143 is about 200 millimeters. The upper distributing pipes 143 are horizontally perpendicular to the second channel 1422, and are parallel to the rollers 123, 125, 127, and 129. Each of the upper distributing pipes 143 has a number of upper spraying nozzles 144 equidistantly mounted along the length of the upper distributing pipe 143. There may be around six to ten upper spraying nozzles 144 mounted on each of the upper distributing pipes 143. The upper spraying nozzles 144 are opposite to the lower conveying roller group 124 and look down on the top surface of the substrate. The distance between the upper spraying nozzles 144 and the lower conveying rollers 125 is larger than the diameter of the upper conveying roller 123, for example, at about 180 millimeters.
The first submersible pump 141 may be selected to operate in an activated state where the first submersible pump 141 supplies etchant to the first supplying pipe 142 thereby enabling the upper spraying nozzles 144 to spray etchant onto the top surface of the substrate, or in an unactivated state where the first submersible pump 141 stops supplying etchant to the first supplying pipe 142 and the upper spraying nozzles 144.
The lower spraying system 145 includes a second submersible pump 146, a second supplying pipe 147, a number of lower distributing pipes 148, and a number of lower spraying nozzles 149. The second submersible pump 145 is disposed in the tank 100, and is immersed in the etchant received in the tank 100. The second supplying pipe 147 includes a third channel 1471 and a fourth channel 1472 perpendicular to the third channel 1471. The third channel 1471 interconnects the second submersible pump 146 and the fourth channel 1472. The fourth channel 1472 communicates with each of the lower distributing pipes 148. The lower distributing pipes 148 are parallel with each other and are equidistantly arranged below the lower conveying roller group 124. The distance between any two adjacent lower distributing pipes 148 is about 200 millimeters. The lower distributing pipes 148 are parallel with the upper distributing pipes 143, and are horizontally perpendicular to the fourth channel 1472. In the illustrated embodiment, from a vertical perspective, each lower distributing pipe 148 is positioned between two adjacent upper distributing pipes 143. Each lower distributing pipe 148 has around six to ten lower spraying nozzles 149 equidistantly mounted along the length of the lower distributing pipe 148. The lower spraying nozzles 149 are opposite to the upper conveying roller group 122 and look up at the bottom surface of the substrate. The distance between the lower spraying nozzles 149 and the upper conveying rollers 123 is larger than the diameter of the lower conveying rollers 125. In the illustrated embodiment, the distance between the upper spraying nozzles 144 and the lower spraying nozzles 149 is about 360 millimeters.
The second submersible pump 146 may be selected to operate in an activated state where the second submersible pump 146 supplies etchant to the second supplying pipe 147 thereby enabling the lower spraying nozzles 149 to spray the etchant onto the bottom surface of the substrate, or in an unactivated state where the second submersible pump 146 stops supplying etchant to the second supplying pipe 147 and the lower spraying nozzles 149.
The structure of the spraying mechanism 14 is not limited to that of this embodiment. The function of the spraying mechanism 14 may be carried out by other suitable mechanisms capable of spraying etchant onto the substrate.
The suction mechanism 16 includes an upper suction system 160 and a lower suction system 165. The upper suction system 160 includes a first vacuum pump 161, a first connecting pipe 162, and a number of upper suction intakes 163. The first vacuum pump 161 is mounted on the first connecting pipe 162, which is positioned below the upper distributing pipes 143 and above the lower conveying roller group 124. The first connecting pipe 162 is parallel with the second channel 1422, and is horizontally perpendicular to the upper distributing pipes 143 and to the rollers 123, 125, 127, and 129. The first connecting pipe 162 communicates with each of the upper suction intakes 163. The upper suction intakes 163 each have an elongated tubular structure, and are parallel to, and substantially co-extensive with, the upper distributing pipes 143. That is, the upper suction intakes 163 are substantially parallel with the rollers 123, 125, 127, and 129. The central portion of each of the upper suction intakes 163 connects with the first connecting pipe 162. The upper suction intakes 163 are positioned above the lower conveying roller group 124, and are almost in contact with the top surface of the substrate. In the illustrated embodiment, there are two adjacent upper suction intakes 163 positioned between two adjacent upper supporting rollers 127, and between two adjacent subgroups of the upper conveying roller group 122. Each upper suction intake 163 defines an elongated cavity and an elongated opening 1631 therein. The cavity communicates with the first connecting pipe 162. The opening 1631 communicates with the cavity and is exposed at the bottom of the upper suction intake 163. That is, the opening 1631 is closely adjacent to the top surface of the substrate.
The first vacuum pump 161 may be selected to operate in an activated state or an unactivated state. In the activated state, the first vacuum pump 161 evacuates the air, so the air pressure of the opening 1631 is reduced and the upper suction intakes 163 are capable of sucking up any etchant on the top surface of the substrate. In the unactivated state, the first vacuum pump 161 stops evacuating the air from the upper suction intakes 163, and then the upper suction intakes 163 cease suction.
The lower suction system 165 includes a second vacuum pump 166, a second connecting pipe 167, and a number of lower suction intakes 168. The second vacuum pump 166 is mounted on the second connecting pipe 167, which is positioned above the lower distributing pipes 148 and below the upper conveying roller group 122. The second connecting pipe 167 is parallel with the first connecting pipe. The second connecting pipe 167 communicates with each of the lower suction intakes 168. The structure of the lower suction intake 168 is similar to that of the upper suction intake 163. The lower suction intakes 168 are positioned below the upper conveying roller group 122, and are almost in contact with the bottom surface of the substrate.
The second vacuum pump 165 may be selected to operate in an activated state where the second vacuum pump 165 reduces the air pressure in the lower suction intakes 168 to suction up any etchant on the bottom surface of the substrate, or in an unactivated state where the second vacuum pump 165 stops evacuating air out and then the lower suction intakes 168 stop functioning.
The geometry between the upper suction system 160 and the lower suction system 165 is such that the suction force applied to the top surface of the substrate by the upper suction system 160 balances the suction force applied to the bottom surface by the lower suction system 165. As such, the substrate is not deformed in any way.
The structure of the suction mechanism 16 is not limited. The function of the suction mechanism 16 may be carried out by other suitable mechanisms capable of simply sucking etchant from the substrate.
The controller 18 can be central processing unit. The controller 18 connects and communicates with the pumps 141, 146, 161, and 166, and is configured for controlling the state of the pumps 141, 146, 161, and 166. Each of the pumps 141, 146, 161, and 166 are alternately operated in the activated state and the unactivated state. In detail, the controller 18 activates the submersible pumps 141 and 146 when the vacuum pumps 161 and 166 are unactivated, and switches off the submersible pumps 141 and 146 when the vacuum pumps 161 and 166 are activated. The duty cycle of the submersible pumps 141 and 146 is equal to the duty cycle of the vacuum pumps 161 and 166. In actual operation, the controller 18 activates the submersible pumps 141 and 146 for a predetermined period of time (and leaving the vacuum pumps 161 and 166 unactivated for the same length of time), and then reverses the functions, to activate the vacuum pumps 161 and 166 for the same predetermined period of time while switching off and leaving the submersible pumps 141 and 146 unactivated for that period of time. The predetermined period of time can be one to three seconds. It is noted that the state of the submersible pumps 141 and 146 are the same at any time, and the vacuum pumps 161 and 166 also have the same state at any time.
Referring to
Firstly, a substrate 200 is provided and positioned between the upper and lower roller groups 122 and 124. The substrate 200 has a top surface 201 and an opposite bottom surface 202, wherein the top surface 201 is in contact with the upper conveying roller group 122 and the upper supporting roller group 126, and the bottom surface 202 is in contact with the lower conveying roller group 124 and the lower supporting roller group 128. The substrate 200 can be a single-sided copper clad laminate (CCL), a double-sided CCL, or a multilayer substrate having inner circuits defined therein. In the illustrated embodiment, the substrate 200 is a double-sided CCL, having a coating of copper foil on the top and bottom surfaces 201 and 202.
Then, the substrate 200 is moved along by the rotation of the conveying rollers 123 and 125.
During the conveyance of the substrate 200, the controller 18 controls the submersible pumps 141 and 146. Thus, the upper spraying nozzles 144 spray the etchant onto the top surface 201 to etch the copper foil on the top side, and the lower spraying nozzles 149 spray the etchant onto the bottom surface 202 to etch the copper foil on the bottom side. After a predetermined period of time, the controller 18 deactivates the submersible pumps 141 and 146, and simultaneously activates the vacuum pumps 161 and 166. Then the upper suction intakes 163 suck any etchant from the top surface 201, and the lower suction intakes 168 suck any etchant from the bottom surface 202. After the lapse of the same predetermined period of time, the submersible pumps 141 and 146 are again activated as the vacuum pumps 161 and 166 are simultaneously deactivatated. As the above mentioned processes are repeated again and again during the conveyance of the substrate 200, the copper foils of the substrate can be efficiently and reliably etched to form electrical traces.
Any post-reaction etchant remaining on the top and bottom surfaces 201 and 202 is removed by the suction mechanism 16, and any new etchant can be sprayed onto and react properly with the copper foil on the top and bottom sides of the substrate 200. Then the copper foil can be etched quickly and precisely. That means the configuration of the traces is precise, and the electrical properties of the manufactured PCBs are reliable.
It should be emphasized that the described embodiments of the present disclosure are merely possible examples of implementations, set forth for a clear understanding of the principles of the disclosure. Many variations and modifications may be made to the above-described embodiment(s) of the disclosure without departing substantially from the spirit and principles of the disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and the present disclosure is protected by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201010517860.4 | Oct 2010 | CN | national |
