TW200421959A - Method of fabricating multi-layer printed circuit board - Google Patents

Abstract

A method of fabricating a build-up multi-layer board includes providing a multi-layer board on which has at least a conductive layer and a conductive through hole. A photo resist layer is formed on the conductive layer, which has the pattern of a circuit and blind via pad. A conductive material, such as solder, is printed on the conductive layer and is then treated by reflowing, so as to be positioned on the blind via pad for electrical conductivity. The self-alignment of the conductive material applied on the fabrication of conductive blind via simplifies the process of a build-up multi-layer board. Next, the pattern of circuit is formed with the photo resist layer and the conductive blind via as an etching mask. Then an out-layer circuit is formed after the removal of the photo resist layer and the formation of an insulative layer.

Description

2Θ04219

V. Description of the invention (1) 1. [Technical field to which the invention belongs] The present invention relates to a method for manufacturing a multilayer circuit board, and relates to a method for manufacturing a multi-layered multilayer board. hole. I. [Previous Technology] The printed circuit board (PCB) is called the mother of the system product. It embeds various electronic components and provides a platform. It is a necessary component for all electronic products. Printed circuit boards are single-sided, double-sided, and multi-layered. Due to the recent electronic product type, light weight, thin, high speed, high performance, high density, low cost, and electronic packaging technology, they have also moved to high pin count and refined (fi ne ) And exhibitions, so printed circuit boards are also moving towards high-density wiring, thin lines, small holes, multi-layering, and thinning. In terms of the number of layers, the most commonly applied technologies are multi-layer board technology (bui Id up) and high-density interconnect technology (High Density Interconnection (HDI) °). The so-called build-up method is based on the traditional laminated multi-layer board, and copper ( RCC) or copper foil plus film to increase the layer, and its internal circuit board using the Micro via micro blind via. The first a to the first e are schematic cross-sectional views of a conventional multilayer multilayer board. As shown in FIG. 1A, a board is provided including a dielectric layer 1 2 6 between two copper cymbals 1 2 4. Using the method ', such as mechanical drilling, a number of 1 2 3 penetrating through the multilayer board are produced. After that, hole copper 1 2 1 is plated in the through holes 1 2 3. Then, the special materials have their own electronic relay transmission, which can be slightly divided to reduce, to accumulate and develop, and to add layers.

Connect with adhesive L to make multi-layer appropriate general L; First B

Tick 4219

V. Description of the invention (2) Figure. In the present invention, the resin through hole (r e s p n u g g i n g) is used to fill the through hole 123 (pass through hole, PTH), and then copper 125 is bonded. After that, a photoresist layer is formed on the surface copper 1 25, and the pattern with the inner layer circuit is transferred to the photoresist layer. After etching the surface copper 1 2 5 and the copper foil 1 24, the photoresist layer is stripped. The remaining surface copper 1 2 5 and the copper foil plate 1 2 4 constitute the inner layer circuit, as shown in the first C diagram. Next, referring to the first D diagram, a dielectric layer 1 2 7 is first formed to cover the entire multilayer board. Then, using a suitable method, such as a laser drilling method, a blind via 128 is formed before the upper surface of the multilayer board, above the through hole 1 2 3 and the lower square. Moreover, as shown in the first E diagram, the multilayer conductive board is covered with a plated conductive layer and the blind holes 1 2 8 are filled. Finally, the conductive layer is pattern-transferred and etched to form a circuit 130 and a conductive blind hole 1 2 9. Lei Zeng needs the board to use the same wet layer. The copper lead layer of the process is wrong. The increase of the hole system is changed. The blind hole plating system will be blindly transmitted to the trunk system. If it is passed, then, and the hole system, where you need to drill holes, you need to limit the memory, and then shoot the dry technique to prepare for the pass. Lei Ruoji has set up redundant guides due to the complexity of holes on the upper layer and other drilling holes. The air-tight fine mines with multiple steps and blind shots or multiple layers of holes on the upper layer are drilled outside the hole. For the system-based system and the system-based system, the system is designed to be used for wet-and-retain uploading and uploading by machine type. It is expected to increase the quantity, work volume, and production time. Fang Kai blindly made the first shot plus the third. [Abstract] For the above, in order to simplify the complexity of the multilayer build-up process, the present

Page 6 2904219 V. Description of the invention (3) The invention provides a method for making a multilayer, multi-layer board, which directly forms a blind hole pattern with a photoresist, instead of the traditional laser drilling process, and saves the cost of the blind hole process. For simplifying the manufacturing process of the inner multi-layer board, the present invention provides a method for manufacturing a multi-layer multi-layer board, which directly forms a blind hole pattern by using a photoresist, and uses a method of solder printing and reflow to make the conduction of the blind hole. For simplifying the conduction of vias or blind vias, the present invention provides a method for manufacturing a multilayer circuit board. The method is to conduct the vias of a conductive plug hole, and to make the vias of a blind hole by solder printing and reflow. Abandon the general wet process and turn-on process, and also save the area occupied by blind holes and through holes. The method covers the surface of a line. Conductive material Conductive material Conductive blind hole and blind hole engraving. According to the above-mentioned containing surface. With at least the materials, examples, use it. Simplified conductivity. Next, the present invention provides a square multi-layered board for manufacturing an additive multilayer board, which at least includes a conductive via and a conductive layer to form a photoresistive layer on the conductive layer, which has a pattern of blind via pad. (Tin is on the conductive layer, and then the solder is located at the position of the blind hole pad. Based on the self-alignment characteristics of the material, the process of the straight multilayer board is etched. After that, the barrier is etched, and the conductive layer lines are printed as blind as possible. A material removing hole pad is used to brush the electrical material to increase the conductivity to form an insulating layer, and at least one process is included to form an electrical connection to form a photoresist layer to etch the insulating layer.

Page 7 Lion 4219 V. Description of the invention (4) A patterned outer layer circuit is formed. 4. [Embodiments] The present invention is described in detail with schematic diagrams. In the detailed description of the embodiments of the present invention, the cross-sectional view showing a multilayer circuit board will not be partially enlarged according to the general scale to facilitate the description, but it should not be used as a limitation. Cognition. In addition, in actual production, three-dimensional space dimensions of length, width and depth should be included. The invention provides a method for manufacturing a multilayer board, which is applied to a printed circuit board and includes providing two conductive layers and a first dielectric layer, wherein the first dielectric layer is located between the two conductive layers. Two photoresist layers are formed on the two conductive layers respectively, and the two photoresist layers expose a part of the two conductive layers. A conductive material is formed on the partially exposed two conductive layers, and then the conductive material is processed by reflow, so that the conductive material forms at least one conductive blind via (pos t) on any two conductive layers. The second figure is a schematic flow chart of a method for manufacturing an increased multilayer board according to the present invention. Referring to the second figure, the present invention provides a multilayer board (step 10). In one embodiment, the multilayer board includes a dielectric layer between two copper box boards. Next, a through hole is drilled in the multilayer board by an appropriate method such as mechanical drilling (step 12). After that, the through-hole conduction and the copper mining process of the two copper boxes are performed (steps 14). In the present invention, a full hole is plugged by using a conductive material plug hole (p 1 u g g i n g), replacing the original wet process copper ore, and simplifying the conduction process of the through hole.

Page 8 2904219 V. Description of the invention (5)

Next, in the method of the present invention, a blind hole pad and a circuit pattern are directly formed using a photoresist to make a blind hole and a circuit (step 16). In one embodiment, a photoresist layer is formed on the two copper foils in any suitable manner, and then the pattern with the circuit and the blind hole pad is transferred to the photoresist layer. Such a photoresist pattern can be used as Blind holes are formed directly. Next, a conductive material is printed on the photoresist layer having a blind hole pattern, and reflow soldering (ref 1 0w) of the conductive material is performed (step 18). In the present invention, a conductive material is printed on the position of the blind hole pattern by means of selective printing. The conductive material may be a low-melting metal or alloy. In one embodiment, the conductive material is solder. Furthermore, one of the features of the present invention is that the conductive material has the characteristics of self-alignment (se 1 f-a 1 ignment). During reflow, the conductive material can flow back to the position of the blind hole, which compensates for the accuracy of printing. problem. Through this step, the conduction of the blind hole can be directly formed. Therefore, one of the features of the present invention is to design a photoresist and a conductive material with self-alignment through printing and re-soldering to complete the conduction of the blind hole. After the conventional laser drilling and wet process conduction processes, the two copper box boards are processed in an appropriate manner, such as etching, to etch out the circuit patterns on the two copper foil boards (step 20), and the photoresist is stripped. Then an appropriate method is used to form an insulating layer and an outer conductive layer on the multilayer board, and to form an outer circuit on the outer conductive layer (step 2 2). The third A to the third E are 2904219 for making a multilayered board according to the present invention. 5. Description of the invention (6)

Schematic cross-section. Referring to FIG. 3A, a multilayer board is provided, which includes a dielectric layer 26 between two copper foil boards 28 and a plurality of through holes 23 passing through the multilayer board. In the present invention, the multilayer board can be used as the inner layer of the multilayer circuit board, but is not limited to this application, and the through hole 23 is made by a suitable method, such as a mechanical drilling method. Next, referring to FIG. 3B, in the present invention, the conventional wet process method is replaced by a conductive material plug hole method, so that the through hole 23 has a conductive via hole 23 that is electrically conductive due to the conductive plug hole. One of the features of the present invention is that the conductive material is used to plug holes to simplify the manufacturing process of conductive vias. It should be noted that as long as it is suitable as a conductive material of a printed circuit board, it does not depart from the scope of application of the present invention. After that, a layer of copper 24 is plated on the two copper foil plates 2 8 by a general copper plating method for subsequent use. Referring to the third figure C, a photoresist layer 32 is formed on the copper 24 first, and then the pattern having the lines 31 and the blind hole pad 30 is transferred to the photoresist layer 32. In the present invention, the 'through-holes 2 3 are already filled with a conductive material' and have copper 2 4 thereon 'to provide position design blind holes. Therefore, the blind hole and the through hole 23 of the present invention can be overlapped and located in an up-and-down position. This saves the area occupied by the blind hole and the through hole 23 and improves the flexibility of circuit design. One of the features of the present invention is that a photoresist layer having a pattern of lines and a blind hole pad is used to expose the blind hole pad, without the need to purchase an expensive laser drilling machine. ® Refer to Figure 3D, apply the conductive material to the blind hole pad 30 on the photoresist layer 32 by selective printing first, and then use the ref low method to make the conductive material self-align. Position of the blind hole pad 30 2904219 V. Description of the invention (7). One of the features of the present invention is that the conductive material is melted into a liquid when reflow soldering is used, and the cohesive force of the liquid conductive material causes the conductive material to aggregate. In addition, the material of the blind hole pad 30, that is, the exposed copper 24, has a tensile effect on the conductive material, so that it is located at the position of the blind hole. In the present invention, the conductive material may be a metal or alloy with a low melting point, such as solder, as long as it can be applied to the plugging process, it belongs to the application scope of the present invention. One of the features of the present invention is that the conductive material has self-alignment characteristics during reflow. Even if some deviations in selective printing cause the conductive material to remain on the photoresist, the conductive material can be aligned during reflow. The position of the blind hole pad 30 completes the conductive blind hole 40. Therefore, one of the features of the present invention is to use conductive materials such as printing and re-soldering to replace conventional laser drilling and wet processes to make conductive blind holes. In addition, due to the characteristics of solder, the thermal conduction of the conductive blind hole of the present invention is better than that of the conventional blind hole. In addition, due to the self-aligning nature of the conductive material, the area required for the blind hole pad is smaller than that required for the conventional laser drilling process, so the wiring density of the inner layer wiring of the multilayer board can be increased. Next, as shown in FIG. 3E, using the photoresist layer 32 and the conductive blind hole 40 as a mask, the copper foil 28 and the copper 24 are etched, and the photoresist layer 32 is removed. Continue to sequentially form an insulating layer 3 4 and a conductive layer on the multilayer board, and then fabricate an outer layer circuit 38 on the conductive layer. In the present invention, in consideration of the flatness problem caused by the conductive blind hole 40, after the insulating layer 34 is formed, a flattening (ρ 〇 1 i s h i n g) step is performed before the conductive layer is formed. One of the features of the present invention is that the conductive blind hole 40 is formed by self-alignment of the conductive material, and has a shape of an upward protrusion, which reduces the conductive blind hole 40 and

Page 11 2904219 V. Description of the invention (8) The contact area of the conductive layer forming the outer layer circuit 38. Therefore, the reduction of the area of the outermost conductive pad above the 'conductive blind hole 40' contributes to the layout density of the outer layer circuit 38 or the component. In summary, the method of the present invention uses a conductive material to plug holes to simplify the manufacturing process of conductive vias; a photoresist layer with a pattern of lines and blind hole pads is used to form a blind hole pad, without using an expensive laser drilling machine Stage; the use of conductive materials with self-alignment characteristics during reflow, making conductive blind holes; conductive blind holes formed using conductive materials, with better thermal conductivity and smaller upper contact area, can improve the inner layer of the circuit The wiring density can reduce the area of the outermost conductive pad above. The above-mentioned embodiments are only for explaining the technical ideas and characteristics of the present invention, and the purpose is to enable those skilled in the art to understand the content of the present invention and apply it accordingly. The scope of the patent, that is, any equivalent change or modification made according to the spirit disclosed by the present invention, should still be covered by the patent scope of the present invention.

Page 12 2904219 Brief description of the drawings 5. [Illustration of the shoulder chart of the drawings] The first A to the first E are schematic cross-sectional views of the traditional production of multi-layer multilayer boards. The second figure is a schematic flow chart of a method for manufacturing an increased multilayer board according to the present invention. Figures A through E are schematic cross-sectional views of a multilayer build-up board according to the present invention. Description of component symbols: 1 0 ~ 2 2 step 2 3 conductive vias 24 copper 26 dielectric layer 28 copper foil_ 3 0 blind hole pad 3 1 circuit 3 2 photoresist layer 3 4 insulating layer 38 outer layer circuit 40 conductive blind Hole 121 hole copper 1 2 3 through hole 1 2 4 copper pig plate 1 2 5 side copper

Page 13 2904219

Claims (1)

This layer of conductance-contains • · Includes less packages, and the board method is more AR = mouth plate, layered multi-layered multi-layered multi-layered for additional mention; a kind of {{a layer of sound pad with a picture package with holes} The layer blindly blocks the light, the layer, the mouth, and the opening layer on the case. The electrograph is guided by the material. The metal material in the hole electrical layer is blindly guided. One by one the light is less than the first. } b C Γ \ -ΓX is as low as derivative. A hole should be blind to make one's material to be used as electricity, and a bit of the cushioning hole should be placed blindly at the welding position and back to the right; the material is opened from the d port C in the row. Case 2904219 6. Scope of patent application 2. The method for making a multi-layer multilayer board as described in item 1 of the patent application scope further includes: removing part of the conductive layer to form the circuit, and the removing step is based on the light The resist layer and the blind via are a mask; and the photoresist layer is removed. 3. The method for manufacturing a multi-layer multilayer board according to item 1 of the patent application scope, wherein the step (a) further comprises: removing a part of the multilayer board to form at least one through hole in the multilayer board; using a second conductive A material plugging method is used to fill the via hole for electrical conduction; and a third conductive material is plated on the via hole and the conductive layer. 4. If the method of making a multi-layered multi-layer board is applied for item 3 of the scope of patent application, which Page 15 2904219 6. The position of the blind hole in the scope of patent application is above the through hole. 5. If the method of making a layered multilayer board according to item 3 of the patent application scope further includes removing part of the third conductive material and the conductive layer to form the circuit, the removing step is based on the photoresist layer and The conductive blind hole is a mask. 6. The method for manufacturing a multi-layer multilayer board according to item 1 of the patent application, wherein the step (c) includes forming the first conductive material by printing. 7. The method for manufacturing a build-up multilayer board according to item 1 of the application, wherein the first conductive material comprises a solder material, a low melting point alloy material, or a low melting point metal material. 8. A method for manufacturing a multilayer board, which is applied to a printed circuit board. The method for manufacturing a multilayer board includes: (a) providing two conductive layers and a first dielectric layer, the first dielectric layer being located on the two conductive layers; Between the two layers; (b) forming two photoresistive layers on the two conductive layers, the two photoresistive layers exposing part of the two conductive layers; (c) forming a first conductive material on the two conductive layers that are partially exposed Layer; and (d) the first conductive material is processed by reflow, so that the first conductive material aligns itself to form at least one conductive blind hole on either of the two conductive layers. K6Page 2904219 6. Application for Patent Scope 9. The method for making a multilayer board according to item 8 of the patent application scope further includes: removing part of the two conductive layers and the first dielectric layer to form at least one through hole in the two A conductive layer and the first dielectric layer; filling the via hole with a second conductive material for electrical conduction; and plating a third conductive material on the via hole and the two conductive layers . 10. The method for manufacturing a multilayer board according to item 8 of the scope of patent application, further comprising: removing a part of the two conductive layers to form a circuit, the removing step is based on the photoresist layer and the conductive blind hole as A mask; and removing the photoresist layer. 1 1. The method for manufacturing a multilayer board according to item 10 of the patent application scope, further comprising forming a second dielectric layer on the conductive blind hole and the circuit line. 12. The method for manufacturing a multilayer board according to item 8 of the scope of patent application, wherein the two conductive layers include two copper box layers. 1 3. The method for manufacturing a multilayer board according to item 8 of the scope of patent application, wherein the first conductive material comprises a solder material, or a low melting point alloy material, or a low melting point metal material. 1 4. The method for making a multilayer board according to item 8 of the scope of patent application, wherein (c Page 17 2904219 VI. Scope of Patent Application) The steps include forming and forming the first conductive material by printing. 1 5. A blind via structure is located in a multilayer board. The multilayer board has a multilayer board core. The blind via structure includes: a bottom surface, which is connected to one of the cores relatively close to the multilayer board. On the conductive layer; a top surface connected to a second conductive layer relatively far away from the core of the multilayer board; and a convex arc surface caused by the cohesion of a blind hole material among which the bottom surface and the first surface The area where the conductive layer contacts is larger than the area where the top surface contacts the second conductive layer. 16. The blind via structure according to item 15 of the patent application scope, wherein the material of the blind via comprises a solder material. 17. The conductive blind hole structure according to item 15 of the patent application scope, wherein the material of the blind hole comprises a low melting point alloy material. 18. The conductive blind hole structure according to item 15 of the patent application scope, wherein the material of the blind hole comprises a low melting point metal material. Page 18