Fcbga pattern exposure process

Abstract

The application discloses a kind of FCBGA pattern exposure processes, comprising: step A: on circuit board, drill through hole;Step B: resin hole machine is used to resin hole to form resin hole to through hole with resin plug hole, wherein, resin hole inside contains resin material for protecting through hole;Step C: determine cutting area on the jig identical with the shape of circuit board, cutting area is carried out to cutting area, wherein, cutting area is the area corresponding to jig and resin hole;Step D: the jig is placed on the surface of thickening layer, and the thickening layer is cut along the edge of jig, so that the shape of thickening layer is identical with the shape of jig;Step E: the thickening layer is covered on the surface of circuit board, and the surface of circuit board forms exposed area not covered by thickening layer, and resin hole is located in exposed area;Step F: resin hole is used as the positioning hole of LDI exposure, and the circuit board after being attached to thickening layer is subjected to LDI exposure, and the application can improve the accuracy of LDI alignment, and improve production efficiency.

Description

Technical Field

[0001] This invention relates to the field of FCBGA (Flip Chip Ball Grid Array) patterning exposure, and particularly to FCBGA patterning exposure technology. Background Technology

[0002] In current LDI (Laser Direct Imaging) exposure, the main methods used are laser targeting or drilling through-holes on the circuit board for positioning. In the through-hole drilling method, large-diameter through-holes are mainly used as positioning holes, such as through-holes with a diameter of 2 mm as positioning holes for circuit LDI exposure. However, using large-diameter through-holes is prone to problems such as hole breakage, burrs, and flash during processing, which can lead to deformation of the through-holes, thereby affecting the alignment accuracy, causing exposure misalignment, and reducing the production yield. Summary of the Invention

[0003] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes an FCBGA patterning exposure process that can improve the alignment accuracy of LDI and increase production efficiency.

[0004] According to a first aspect of the present invention, an FCBGA patterning exposure process includes:

[0005] Step A: Drill through holes on the circuit board;

[0006] Step B: Use a resin plugging machine to plug the through hole with resin to form a resin hole, wherein the resin hole contains resin material for protecting the through hole;

[0007] Step C: Determine a cutting area on a fixture with the same shape as the circuit board, and cut the cutting area, wherein the cutting area is the area of ​​the fixture corresponding to the resin hole;

[0008] Step D: Place the fixture on the surface of the thickened layer, and cut the thickened layer along the edge of the fixture so that the shape of the thickened layer is the same as the shape of the fixture;

[0009] Step E: The thickening layer is applied to the surface of the circuit board, forming an exposed area on the surface of the circuit board that is not covered by the thickening layer, and the resin holes are located in the exposed area;

[0010] Step F: Using the resin holes as positioning holes for LDI exposure, perform LDI exposure on the circuit board after it is bonded to the thickened layer.

[0011] The FCBGA patterning exposure process according to embodiments of the present invention has at least the following beneficial effects: resin holes are formed by resin plugging the through holes on the circuit board, and the through holes are protected with resin to prevent deformation during subsequent processing. The thickened layer is cut by making a fixture so that the resin-filled through holes are not covered after the thickened layer is bonded to the circuit board, that is, the resin holes are directly exposed on the surface of the circuit board. Therefore, in LDI exposure, the through holes exposed on the circuit board can be directly used as positioning holes, which helps to improve the accuracy of LDI alignment, increase production efficiency, and improve the yield of products.

[0012] According to some embodiments of the present invention, the distance between the edge of the through hole and the edge of the circuit board in step A is between 2 mm and 5 mm.

[0013] According to some embodiments of the present invention, step A, in which the through hole is drilled on the circuit board, further includes dust removal to keep the circuit board clean.

[0014] According to some embodiments of the present invention, step B further includes using a resin polishing machine to polish and remove resin from the circuit board except for the through holes.

[0015] According to some embodiments of the present invention, in step C, after the fixture is cut, the distance between the cut edge of the fixture and the through hole is 2 mm to 5 mm.

[0016] According to some embodiments of the present invention, after step E, the circuit board and the thickening layer are further pressed together to make the circuit board and the thickening layer fit tightly together.

[0017] According to some embodiments of the present invention, the diameter of the through hole is between 0.01 mm and 1 mm.

[0018] According to some embodiments of the present invention, the fixture is an FR4 part.

[0019] According to some embodiments of the present invention, the thickening layer is a resin-coated copper foil.

[0020] According to some embodiments of the present invention, step C further includes making a mark on the fixture to distinguish the front and back sides, so that the thickened layer can be distinguished as front and back sides after cutting.

[0021] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0023] Figure 1 This is a flowchart of one embodiment of the FCBGA patterning exposure process of the present invention. Detailed Implementation

[0024] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0025] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0026] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0027] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0028] Reference Figure 1 The flowchart is a representation of an embodiment of the FCBGA patterning exposure process of the present invention, including:

[0029] Step A: Drill through holes on the circuit board.

[0030] In step A, through holes are drilled on the circuit board using mechanical drilling. The through holes must be formed in one drilling operation to avoid unevenness of the inner wall of the through hole due to secondary drilling. This would reduce the protective effect of the resin on the through hole during the subsequent resin plugging process because there is a gap between the resin and the through hole.

[0031] Understandably, the diameter of through holes ranges from 0.01 mm to 1 mm. In subsequent processing, problems such as broken holes, burrs, and flash are less likely to occur, causing deformation of the through holes. This allows the through holes to occupy a smaller area of ​​the circuit board, making them suitable for smaller circuit boards.

[0032] Understandably, the distance between the edge of the through hole and the edge of the circuit board is between 2 mm and 5 mm to prevent uneven stress on the circuit board during drilling, which could cause cracks between the through hole and the circuit board and affect the product yield.

[0033] It should be noted that the circuit board includes a first side and a second side, which are perpendicular to each other. The shortest distance between the edge of the through hole and the first side is between 2 mm and 5 mm, and the shortest distance between the edge of the through hole and the second side is between 2 mm and 5 mm.

[0034] It is understandable that multiple through holes are drilled on the circuit board. By drilling multiple through holes, the positioning accuracy of the circuit board in LDI exposure is further improved.

[0035] Understandably, in another embodiment, the circuit board is rectangular, including a first side, a second side, a third side, and a fourth side. The first side is perpendicular to the second side, the second side is perpendicular to the third side, the third side is perpendicular to the fourth side, and the fourth side is perpendicular to the first side. A first through hole and a second through hole are drilled on the circuit board. The center points of the first through hole and the second through hole are located on the diagonal of the circuit board. The shortest distance between the edge of the first through hole and the first side is between 2 mm and 5 mm. The shortest distance between the edge of the first through hole and the second side is between 2 mm and 5 mm. The shortest distance between the edge of the second through hole and the third side is between 2 mm and 5 mm. The shortest distance between the edge of the second through hole and the fourth side is between 2 mm and 5 mm. The circuit board is positioned through the first through hole and the second through hole, making the positioning of the circuit board more accurate during LDI exposure. In addition, the circuit board can also be drilled with a first through hole, a second through hole, a third through hole, and a fourth through hole. The shortest distance between the edge of the first through hole and the first side is between 2 mm and 5 mm. The shortest distance between the edge of the first through hole and the second side is between 2 mm and 5 mm. The shortest distance between the edge of the second through hole and the second side is between 2 mm and 5 mm. The shortest distance between the edge of the second through hole and the third side is between 2 mm and 5 mm. The shortest distance between the edge of the third through hole and the third side is between 2 mm and 5 mm. The shortest distance between the edge of the third through hole and the fourth side is between 2 mm and 5 mm. The shortest distance between the edge of the fourth through hole and the first side is between 2 mm and 5 mm. Using four through holes as positioning holes allows the shape of the positioning circuit board to be accurately determined during LDI exposure, improving the positioning accuracy.

[0036] Understandably, the drilling process also includes dust removal, using a vacuum cleaner to remove debris and dust generated during drilling, to prevent the circuit board and the thickened layer from not being able to fully adhere due to debris and dust on the circuit board.

[0037] It should be noted that if there is a gap between the circuit board and the thickened layer, the chemical reagents may enter the gap between the circuit board and the thickened layer during the chemical etching process, causing wear on the circuit board and affecting its actual use.

[0038] Step B: Place the circuit board on the resin plugging machine and plug the through holes with resin to form resin holes.

[0039] In step B, the resin plugging is done using vacuum resin plugging. Vacuum plugging can effectively control the amount of resin used during the plugging process, avoiding the situation where excessive resin overflows from the through hole onto the circuit board.

[0040] It should be noted that if there is too much resin on the circuit board, it will seriously affect the efficiency of resin grinding, that is, the resin grinding time will increase, thereby reducing production efficiency.

[0041] It should be noted that during the plugging process, no holes should be left unplugged or allowed to let light through, in order to ensure the resin's protective effect on the through holes. By plugging the through holes with resin, wear on the through holes can be effectively prevented during subsequent processing.

[0042] Understandably, after the through holes are filled with resin, a grinding machine is also used to grind the resin that has overflowed from the through holes onto the circuit board, in order to prevent resin from remaining on the circuit board and causing the circuit board to not fully adhere to the thickened layer.

[0043] It should be noted that if there is a gap between the circuit board and the thickened layer, the chemical reagents may enter the gap between the circuit board and the thickened layer during the chemical etching process, causing wear on the circuit board and affecting its actual use.

[0044] It is understood that the amount, color, and type of resin used in the resin plugging can be adjusted according to actual production needs, and no specific restrictions are imposed in this embodiment.

[0045] It should be noted that, in another embodiment, black resin ink is used to plug the through holes, which can effectively prevent the resin from transmitting light. Furthermore, using black resin ink makes it easier to observe and judge the plugging situation and the quality status after grinding.

[0046] Step C: Determine the cutting area on a fixture with the same shape as the circuit board, and cut the cutting area, wherein the cutting area is the area of ​​the fixture corresponding to the resin hole.

[0047] Understandably, a cutting machine or utility knife can be used to cut the fixture.

[0048] Understandably, before cutting the fixture, it is also necessary to mark the through holes on the fixture. The position of the through hole mark corresponds to the position of the through hole on the circuit board. The cutting area is determined around the through hole mark with the through hole mark as the center. The shortest distance between any side of the cutting area and the through hole mark is between 2 mm and 5 mm to ensure that the fixture does not block the through hole.

[0049] It is understandable that a cutting machine is used to cut the fixture from top to bottom, so that the cut surface of the fixture is perpendicular to the surface of the circuit board after cutting.

[0050] It is understandable that a 2mm mark is made on the cutting edge of the fixture from the outside in. This mark allows the front and back of the thickened layer to be distinguished by the fixture, preventing incorrect bonding between the thickened layer and the circuit board due to misidentification of the front and back of the thickened layer.

[0051] It is understood that, in another embodiment, the jig includes a front and a back side, with a mark located at the lower left of the front side and a mark located at the lower right of the back side. After the thickened layer is cut using the jig, the mark is located at the lower left of the front side of the thickened layer and a mark is located at the lower right of the back side of the thickened layer.

[0052] Understandably, in another embodiment, the circuit board is rectangular, including a first side and a second side, which are perpendicular to each other. The fixture, which has the same shape as the circuit board, includes a third side corresponding to the first side and a fourth side corresponding to the second side. The shortest distance between the edge of the through hole and the first side is between 2 mm and 5 mm, and the shortest distance between the edge of the through hole and the second side is between 2 mm and 5 mm. The shortest distance between the through hole mark on the fixture and the third side is between 2 mm and 5 mm, and the shortest distance between the through hole mark on the fixture and the fourth side is between 2 mm and 5 mm. The shape of the cutting area on the fixture is an isosceles right triangle, with the first right-angled side coinciding with the third side and the second right-angled side coinciding with the fourth side. After cutting the fixture, the cutting edge of the fixture is the hypotenuse of the isosceles right triangle, and the shortest distance between the cutting edge and the edge of the through hole is between 2 mm and 5 mm.

[0053] Understandably, in another embodiment, the circuit board is rectangular, including a first side, a second side, a third side, and a fourth side. The first side is perpendicular to the second side, the second side is perpendicular to the third side, the third side is perpendicular to the fourth side, and the fourth side is perpendicular to the first side. The first side of the circuit board corresponds to the first side of the fixture, the second side of the circuit board corresponds to the second side of the fixture, the third side of the circuit board corresponds to the third side of the fixture, and the fourth side of the circuit board corresponds to the fourth side of the fixture. A first through hole, a second through hole, a third through hole, and a fourth through hole are drilled on the circuit board. The center points of the first and third through holes are located on the first diagonal of the circuit board, and the second and fourth through holes are located on the second diagonal of the circuit board. The center points of the first and third through holes are located on the first diagonal of the circuit board. The shortest distance between the edge and the first side is between 2 mm and 5 mm; the shortest distance between the edge and the second side is between 2 mm and 5 mm; the shortest distance between the edge and the second side is between 2 mm and 5 mm; the shortest distance between the edge and the third side is between 2 mm and 5 mm; the shortest distance between the edge and the third side is between 2 mm and 5 mm; the shortest distance between the edge and the fourth side is between 2 mm and 5 mm; the shortest distance between the edge and the third side is between 2 mm and 5 mm; the shortest distance between the edge and the fourth side is between 2 mm and 5 mm; the fixture also has first through holes corresponding to the first, second, third, and fourth through holes. The fixture features a hole mark, a second through-hole mark, a third through-hole mark, and a fourth through-hole mark. Correspondingly, the fixture also has a first isosceles right triangle corresponding to the first through-hole mark, a second isosceles right triangle corresponding to the second through-hole mark, a third isosceles right triangle corresponding to the third through-hole mark, and a fourth isosceles right triangle corresponding to the fourth through-hole mark. The first isosceles right triangle represents the shape of the first cutting area, the second isosceles right triangle represents the shape of the second cutting area, the third isosceles right triangle represents the shape of the third cutting area, and the fourth isosceles right triangle represents the shape of the fourth cutting area. The right-angled side of the first isosceles right triangle coincides with the first and second sides of the fixture, and the right-angled side of the second isosceles right triangle coincides with the right-angled side of the fixture. The second and third sides coincide. The third isosceles right triangle coincides with the third and fourth sides of the fixture. The fourth isosceles right triangle coincides with the fourth and first sides of the fixture. The shortest distance between the hypotenuse of the first isosceles right triangle and the edge of the first through-hole mark is between 2 mm and 5 mm. The shortest distance between the hypotenuse of the second isosceles right triangle and the edge of the second through-hole mark is between 2 mm and 5 mm. The shortest distance between the hypotenuse of the third isosceles right triangle and the edge of the third through-hole mark is between 2 mm and 5 mm. The shortest distance between the hypotenuse of the fourth isosceles right triangle and the edge of the fourth through-hole mark is between 2 mm and 5 mm. A 2 mm mark is cut from the outside to the inside on the hypotenuse of the third isosceles right triangle as a mark to distinguish the front and back sides.

[0054] Understandably, the fixture uses FR4 components, which have excellent electrical properties, high operating temperature, and are less affected by the environment.

[0055] It should be noted that the embodiments of this application do not limit the specific shape of the cutting area. It can be triangular or circular, and the specific shape can be changed according to actual needs.

[0056] Step D: Cutting the thickened layer: Place the jig on the surface of the thickened layer and cut the thickened layer along the edge of the jig so that the thickened layer has the same shape as the jig.

[0057] It is understandable that the thickening layer is a resin-coated copper foil. The front side of the thickening layer is the copper side, and the back side is the resin side. The markings can effectively distinguish the front and back of the thickening layer, avoiding errors when bonding the thickening layer to the circuit board, which would lead to a decrease in the product yield.

[0058] It should be noted that the resin side of the thickened layer is bonded to the circuit board. The resin side and copper side of the thickened layer can be quickly identified by marking, and then bonded to the circuit board, thus improving production efficiency.

[0059] It is understood that in another embodiment, a utility knife is used as a cutting tool to cut the thickened layer.

[0060] Step E: Apply the thickening layer to the surface of the circuit board, creating an exposed area on the circuit board surface that is not covered by the thickening layer. The resin holes are located in the exposed area.

[0061] In step E, after the thickening layer is applied to the surface of the circuit board, the circuit board and the thickening layer are pressed together to ensure that the circuit board and the thickening layer are tightly bonded.

[0062] It is understandable that the shape of the exposed area is the same as the shape of the cutting area on the fixture. That is, after the cutting fixture or the cutting thickened layer is covered on the surface of the circuit board, the area directly exposed on the circuit board is the exposed area of ​​the circuit board.

[0063] It should be noted that in related technologies, there are also technical solutions that cover the circuit board surface with a thickening layer, and then use laser targeting to determine the LDI exposure positioning holes on the covered circuit board. After the thickening layer is covered on the circuit board surface, positioning holes are made on the thickening layer and the circuit board using laser targeting. Then, the target points are used as positioning holes for LDI exposure. However, the laser targeting method is costly and the process is more complex. It requires the creation of precise target points on the circuit board. If the target points are deviated, the LDI exposure of the circuit board will be deviated, resulting in a decrease in product yield. The technical solution of this application is to cut the thickening layer so that when the thickening layer is covered on the circuit board surface, an exposed area is formed on the circuit board. The resin-filled through-holes on the circuit board are located in the exposed area. By using the resin-filled through-holes in the exposed area of ​​the circuit board for positioning, the circuit board can be directly positioned during the LDI exposure process, which is less prone to deviation. Moreover, the resin filling in the through-holes in the exposed area can effectively protect the through-holes from wear during processing, which would affect the LDI exposure alignment accuracy.

[0064] Step F: LDI Exposure: Using resin holes as positioning holes for LDI exposure, LDI exposure is performed on the circuit board after it is bonded to the thickened layer. The resin holes contain resin material to protect the through holes.

[0065] It is understandable that resin holes are through holes filled with resin. Using resin-filled through holes as positioning holes can effectively improve positioning accuracy. Furthermore, because the through holes are protected by resin, they will not wear out during processing.

[0066] Understandably, in another embodiment, the circuit board is rectangular, including a first side, a second side, a third side, and a fourth side. The first side is perpendicular to the second side, the second side is perpendicular to the third side, the third side is perpendicular to the fourth side, and the fourth side is perpendicular to the first side. A first through-hole and a second through-hole are drilled on the circuit board. Both the first and second through-holes are filled with resin to protect them. The center points of the first and second through-holes are located on the diagonal of the circuit board. The shortest distance between the edge of the first through-hole and the first side is between 2 mm and 5 mm. The shortest distance between the edges is between 2 mm and 5 mm. The shortest distance between the edge of the second through hole and the third edge is between 2 mm and 5 mm. The shortest distance between the edge of the second through hole and the fourth edge is between 2 mm and 5 mm. After the circuit board is bonded to the thickening layer, a first exposed area and a second exposed area are formed on the circuit board. The first through hole is located in the first exposed area, and the second through hole is located in the second exposed area. In LDI exposure, the first through hole and the second through hole are used as positioning to determine the diagonal of the circuit board. The position of LDI exposure is adjusted according to the diagonal of the circuit board, and then the circuit board is exposed.

[0067] Understandably, in another embodiment, the circuit board is rectangular, including a first side, a second side, a third side, and a fourth side. The first side is perpendicular to the second side, the second side is perpendicular to the third side, the third side is perpendicular to the fourth side, and the fourth side is perpendicular to the first side. The circuit board has a first through-hole, a second through-hole, a third through-hole, and a fourth through-hole. Each of these through-holes is filled with resin to protect it. The center points of the first and third through-holes are located on the first diagonal of the circuit board, and the second and fourth through-holes are located on the second diagonal. The shortest distance between the edge of the first through-hole and the first side is between 2 mm and 5 mm, the shortest distance between the edge of the first through-hole and the second side is between 2 mm and 5 mm, and the shortest distance between the edge of the second through-hole and the second side is between 2 mm and 5 mm. Between millimeters, the shortest distance between the edge of the second through hole and the third side is between 2 and 5 millimeters, the shortest distance between the edge of the third through hole and the third side is between 2 and 5 millimeters, the shortest distance between the edge of the third through hole and the fourth side is between 2 and 5 millimeters, the shortest distance between the edge of the fourth through hole and the fourth side is between 2 and 5 millimeters, and the shortest distance between the edge of the fourth through hole and the first side is between 2 and 5 millimeters. After the circuit board is bonded to the thickened layer, the first through hole is located in the first exposed area, the second through hole is located in the second exposed area, the third through hole is located in the third exposed area, and the fourth through hole is located in the fourth exposed area. In LDI exposure, the specific shape of the circuit board can be confirmed by using the first through hole, the second through hole, the third through hole, and the fourth through hole as positioning holes. The circuit board is then exposed according to its shape, improving the accuracy of LDI exposure.

[0068] It is understandable that steps E and F include copper reduction → opening copper windows → laser blind holes → filling.

[0069] It should be noted that copper reduction is achieved by using a chemical method to reduce the thickness of the thickened layer to a preset thickness. The preset thickness can be modified according to actual needs, and is not specifically limited in this embodiment.

[0070] It should be noted that opening copper windows involves etching a preset area of ​​the thickened layer. The preset area is the area of ​​the thickened layer corresponding to the blind via on the circuit board. The copper layer in the preset area of ​​the thickened layer is removed by etching.

[0071] It should be noted that laser-etched blind vias are created by using a laser device to etch a preset area, removing the resin layer on the thickened layer and exposing blind vias on the circuit board. Here, a blind via refers to a through-hole that connects the inner layers and is not visible on the surface after the thickened layer is bonded to the circuit board.

[0072] It should be noted that the filling operation involves electroplating copper into the blind hole to make it flat.

[0073] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. An FCBGA patterning exposure process, characterized in that, include: Step A: Drill through holes on the circuit board; Step B: Use a resin plugging machine to plug the through hole with resin to form a resin hole, wherein the resin hole contains resin material for protecting the through hole; Step C: Determine a cutting area on a fixture with the same shape as the circuit board, and cut the cutting area, wherein the cutting area is the area of ​​the fixture corresponding to the resin hole; Step D: Place the fixture on the surface of the thickened layer, and cut the thickened layer along the edge of the fixture so that the shape of the thickened layer is the same as the shape of the fixture; Step E: Cover the circuit board surface with the thickening layer, so that an exposed area is formed on the circuit board surface that is not covered by the thickening layer, and the resin hole is located in the exposed area; Step F: Using the resin holes as positioning holes for LDI exposure, perform LDI exposure on the circuit board after it is bonded to the thickened layer.

2. The FCBGA patterning exposure process according to claim 1, characterized in that, The distance between the edge of the through hole and the edge of the circuit board in step A is between 2 mm and 5 mm.

3. The FCBGA patterning exposure process according to claim 1, characterized in that, In step A, the process of drilling the through holes on the circuit board also includes a dust removal operation to keep the circuit board clean.

4. The FCBGA patterning exposure process according to claim 1, characterized in that, Step B further includes using a resin polishing machine to polish and remove the resin on the circuit board except for the through holes.

5. The FCBGA patterning exposure process according to claim 1, characterized in that, In step C, after the fixture is cut, the distance between the cut edge of the fixture and the through hole is 2 mm to 5 mm.

6. The FCBGA patterning exposure process according to claim 1, characterized in that, After step E, the circuit board and the thickening layer are pressed together to ensure that the circuit board and the thickening layer are tightly bonded.

7. The FCBGA patterning exposure process according to claim 1, characterized in that, The diameter of the through hole is between 0.01 mm and 1 mm.

8. The FCBGA patterning exposure process according to claim 1, characterized in that, The fixture is an FR4 part.

9. The FCBGA patterning exposure process according to claim 1, characterized in that, The thickened layer is a resin-coated copper foil.

10. The FCBGA patterning exposure process according to claim 9, characterized in that, Step C further includes creating markings on the fixture to distinguish the front and back sides, so that the thickened layer can be distinguished after cutting.

Images