KR100914376B1 - Method for manufacturing printed wiring board - Google Patents

Abstract

The present invention is a manufacturing method of a very thin printed wiring board which can produce a multi-stackable printed circuit board, characterized by comprising the following steps:

A. A silicon wafer 20 having a thickness of 50 µm to 300 µm was prepared;

B. attach the silicon wafer 20 to a jig 10 capable of supporting only its periphery, cover the entire surface with a film, and fix the silicon wafer 20 to the jig 10;

C. pattern the film to expose the front and back surfaces of the silicon wafer 20;

D. forming a through hole at a predetermined position of the exposed silicon wafer 20 and forming a metal thin film on an exposed surface of the silicon wafer 20 including the through hole;

E. The metal thin film is patterned and subsequently etched to obtain a predetermined conductor pattern.

Printed wiring board

Description

Manufacturing method of printed wiring board {METHOD FOR MANUFACTURING PRINTED WIRING BOARD}

This invention relates to the manufacturing method of the printed wiring board which uses a very thin silicon wafer as a base material.

In response to requests for high-density mounting of electronic components, multilayered printed wiring boards (multilayer printed wiring boards) are used. However, the multilayer printed wiring board uses a ceramic substrate, a laminated board, a composite laminated board, etc. as the board | substrate, and the board | substrate thickness and the request | requirement on the electrical property did not match.

An object of this invention is to provide the manufacturing method of the very thin printed wiring board which can manufacture the printed circuit board which can be laminated | stacked multistage.

That is, this invention comprises the following steps, The manufacturing method of the printed wiring board characterized by the above-mentioned.

A. A silicon wafer having a thickness of 50 µm to 300 µm was prepared;

B. attach the silicon wafer to a jig capable of supporting only its periphery, cover the entire surface with a film for each jig, and fix the silicon wafer to the jig;

C. patterning the film to expose the front and back surfaces of the silicon wafer (the exposed portion becomes a work area for forming wiring patterns, through holes, and bump lands);

D. forming a through hole at a predetermined position of the exposed silicon wafer, and forming a metal thin film on an exposed surface of the silicon wafer including the through hole; And

E. The metal thin film is patterned and subsequently etched to obtain a predetermined conductor pattern.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows the manufacturing method of the printed wiring board of this invention according to the flow of a main process.

Fig. 2 is a plan view showing a jig for use in the method for producing a printed wiring board of the present invention together with a substrate material supporting it.

FIG. 3 is a partially enlarged cross-sectional view (cut along the line A-A) showing one embodiment of the jig supporting the substrate material shown in FIG.

4 is a partially enlarged cross-sectional view (cut along line A-A) showing another embodiment of the jig supporting the substrate material shown in FIG.

5 is a partially enlarged cross-sectional view (cut along line A-A) showing another embodiment of the jig supporting the substrate material shown in FIG. 2;

FIG. 6 is a partially enlarged cross-sectional view (cut along line A-A) showing yet another embodiment of the jig supporting the substrate material shown in FIG.

Fig. 7 is a partially enlarged cross-sectional view showing a state in which the jig supporting the substrate material shown in Fig. 3 is covered with a film, and the front and back surfaces of the substrate material are exposed.

Where each symbol

10: jig

10a: Juche part of the jig

10b: end of jig

10c: slope part of jig (one slope part)

10d: Slope part of jig (other slope part)

11: one member of the jig

11a: end of one component member of the jig

11b: One structural member of the jig (main part)

11c: slope part of one structural member of jig or slope part of main part (one slope part)

11d: Slope part (other slope part) of one structural member (main part) of the jig

12: member of the other side of the jig

12a: end of the other member of the jig

12b: Other structural member of the jig (donut-shaped member)

12c: slope portion of the other structural member of the jig

13: jig home                 

14 opening

15: coating film

20: substrate material

20a: periphery of substrate material

Respectively.

EMBODIMENT OF THE INVENTION This invention is demonstrated in detail, referring an accompanying drawing which shows embodiment (except FIG. 1, since the objective is showing the mutual relationship and structure of each member, the dimension of illustration is not actual dimension).

1 is a standard process diagram of the present invention.

A. Preparation of the Substrate

In the present invention, a silicon wafer cut out from an ingot is used as the substrate material 20. Its thickness is 50 to 300 µm (related to that for semiconductors, which is 8 inches and 735 µm. In the state of the chip, the thickness is at least about 30 µm, but this is performed by separately grinding the wafer cut out from the ingots). Reduced). In addition, the surface roughness is sufficient as about 1000 kPa-5000 kPa (10 point average roughness: Rz prescribed | regulated to JIS B 0601), and does not require the same mirror finish as that for semiconductors.

B. Attachment to fixture

Since the board | substrate material 20 prepared in the previous process is thin, the said board | substrate is supported by the special jig 10 in consideration of the handling property and processing precision in subsequent processing. Specifically, as shown in FIG. 2, the edge portion 20a of the substrate is shown in an end portion 10b provided in the inner circumferential portion of the main portion 10a of the jig (in the drawing, but shown in the form formed around the entire circumference). It may be provided in the shape of a hook at a predetermined interval in the circumferential direction, in which case it is placed on at least three places from the viewpoint of securing the stability of the support (as described later), Since the board | substrate is integrated with a film, it is usually enough to mount it. Moreover, the jig 10 shown to FIG. 3 consists of one member 10a (henceforth a main part of a jig), In order to more securely support the substrate on the jig, the member is divided into two members 11 and 12, and the ends 11a and 12a (the heights of the ends are respectively the inner periphery of both members, respectively). Of the substrate 1/2), and the shape of the periphery 20a of the substrate may be sandwiched by both members (see Fig. 4), and the end 11a (the height of only one inner periphery of one member 11 may be The same as the thickness of the substrate), and the other member 12 has a flat lower surface thereof and presses the upper surface of the periphery 20a of the substrate placed at the end portion at the tip of the lower surface (see FIG. 5). ), And the jig is a form in which the main body portion 11b (the two members 11 and 12 constituting the jig shown in Figs. 4 and 5) is integrally formed. The bottom portion of the main body portion is formed at a position that is 1/2 of the thickness of the substrate from the center of the thickness of the main body portion, and the depth of the end portion is set to the width thereof, and the outer peripheral portion thereof is the deepest portion of the end portion of the jig. Substantially donut shaped disc 12b (the other part shown in FIG. (12 is a form consisting only of the distal end portion thereof) (see Fig. 6.) In the drawing, reference numeral 14 denotes an opening of the jig (Fig. 2 is drawn with the substrate attached to the jig). , 20 and 14, and 20a and 10b and 11a and 12a and 12b are attached to the same location, respectively. Reference numerals 10a, 11, 11b, and 12 are also attached to the same place because they are viewed from above with the upper and lower surfaces of the members indicated by them contacting each other). Incidentally, the slope portions 10c, 10d, 11c, 11d, 12c, and 11d of the members constituting the jig have a smooth coating process of the jig and the substrate and a metal thin film forming step (1) And / or 2) and so as to uniformize the thickness of the resist applied in the formation process of the conductor pattern (disposing and applying the slot coating coater in the radial direction:: smooth discharge of the spin coating excess resist), etc. ). The angle may be appropriately set depending on the diameter of the substrate to be supported on the jig, the diameter of the jig, and the properties of the resist to be applied. Generally, it selects in the range of 3-10 degrees. In addition, it is preferable to attach appropriate R to the edge part of the said jig | tool, for example, the transition part from an outer peripheral surface to an upper and lower surface, and a corner part, in order to make sure the coating by the film which is the next process.

Here, the jig is made of metal such as aluminum, copper, brass, etc. in that the jig has a certain degree of rigidity and is excellent in electroconductivity and chemical resistance (the jig consists of two members, one of which is one of them). In the aspect which is a donut-shaped disc, since the weight also contributes to support of the said board | substrate, it is preferable to set it as metal). Moreover, the edge part of the said jig | tool is a distance between the upper surface of the said jig and the upper surface of the said board | substrate in the state which mounted the board | substrate on it: H (in the aspect shown to FIG. 4 and FIG. 5, the other side of the jig | tool) The distance between the upper surface of the member and the upper surface of the substrate, the distance between the upper surface of the main body of the jig and the upper surface of the substrate in the embodiment shown in Fig. 6) the distance between the lower surface of the jig and the lower surface of the substrate: H 4 and 5, the distance between the lower surface of one member of the jig and the lower surface of the substrate, and the lower surface of the main part of the jig and the lower surface of the substrate in the embodiment shown in FIG. 6. Distance) is set to be equal. This is because exposure of the upper and lower surfaces of the substrate can be simplified by flipping the upper and lower surfaces of the substrate in utilizing the upper and lower surfaces of the substrate as the formation points in order to increase the density of the conductor pattern. In addition, although the figure with one jig | tool is shown with respect to one silicon wafer as said board | substrate material in a figure, it cannot be overemphasized that the aspect with one jig | tool can be taken for plural sheets of silicon wipers, of course ( From the flexibility of securing the exposure work area, one-to-one correspondence is good, while the one-to-one correspondence is good in terms of the efficiency of formation of the metal thin film described later, so it may be appropriately selected according to the situation). In addition, although shown as a substantially square jig | tool, it is a matter of course that the external shape may be circular or polygonal. In addition, a plurality of air radiates on the upper surface and the lower surface of the jig and the slopes connected thereto (the number may be appropriately selected depending on the diameter of the substrate to be supported on the jig, and thus the diameter of the jig). The release groove 13 is provided in consideration of the synthetic distribution of the jig (the start point or the end point is the outer circumferential end of the jig and the end point or the start point is the inner circumferential end of the slope of the jig). It is for reliably performing the film coating mentioned later. Here, the shape (section) of the groove may be any shape as long as the jig and the air present between the substrate and the film when the film is coated, such as a semicircle, a semi-ellipse, an angle, a triangle, and the like, can be smoothly released. However, it is preferable to attach R in order to ensure the adhesiveness of a film from the upper end of the wall of the said groove to the upper and lower surfaces containing the slope part of the said jig | tool.

C. Cover by Film

In order to ensure the precision of subsequent processing, the said board | substrate material supported by the said jig | tool is coat | covered and fixed with the film 14 with the said jig | tool. As said film, a dry resist, for example, a negative dry film is mentioned as a candidate from the viewpoint of handleability. Moreover, the coating | cover with the said film adheres the said film to the whole jig | tool which the said board | substrate material was supported by the vacuum lamination method etc., for example, and the said film was close to the inner side of the periphery 20a of the said board | substrate. Patterning is performed so that the front and back surfaces of the substrate material except the portion are exposed (see Fig. 7. The substrate material is closely supported by the jig in a state where most of the front and back surfaces (indicated by arrows in the drawing) are exposed. In addition, since Fig. 7 is a sectional view, the coating film should also be displayed with diagonal lines, but the diagonal lines have been devoted in order to avoid display clutter.

D. Formation of Through Hole

Through holes are formed at predetermined positions of the substrate material for multi-stage stacking of printed circuit boards. Since the substrate material is thin in thickness, a laser, for example, a drilling method using a carbon dioxide laser or a YAG laser, a plasma etching method, a photolithography method, or the like can be used as the method for forming the through hole.                 

E. Formation of Metal Thin Film-1

In order to secure the adhesion of the metal thin film-2 described later, a metal thin film-1, for example, IT0 or a thin film of copper [Cu] or the like (thickness: at least 50 kPa) is formed on the surface exposed by the substrate material. As the method, a vapor deposition method is mentioned. On the other hand, for applications in which the thickness of the obtained metal thin film does not have to be very thick, the metal thin film-1 is formed by electroless plating (a thin film of nickel [Ni], and then a part of the nickel thin film is replaced with gold [Au]). ) Can be formed (in this case, the formed thin film is made of a composite film of nickel in the lower layer or base layer, and in the upper layer or the surface layer). The metal thin film-1 is formed not only on the surface of the substrate material but also on the through hole wall surface formed above.

F. Formation of Metal Thin Film-2

On the surface of the substrate material on which the metal thin film-1 is formed, a metal thin film-2, for example, Cu, which is the main body of the conductor pattern is formed. As the method, an electroless plating method can be mentioned (when the electroless plating method is applied in step E, this step is unnecessary). If a thicker metal thin film (thickness: 3 µm or more) is desired, electroplating is again applied. The metal thin film is formed not only on the surface of the substrate material but also on the through hole wall surface formed above.

G. Formation of Conductor Patterns

Resist coating (usually according to the method) is carried out similarly to the formation of a conventional conductor pattern. However, the application of the slot-and-spin method of rotating the jig after application by the slot coater end or by the slot coater is applied. It is preferable because the consumption of sigma can be applied to the concave portion with a small amount of the end .. In addition, the slot coater is disposed in the radial direction of the jig 10 and the substrate 20, and the slot coater is placed in the jig and the jig. It may rotate about the center of a board | substrate), exposure and image development (expose the metal thin film of parts other than a desired conductor pattern), the etching removal of the exposed metal thin film, and the peeling / removal of a resist are performed. In addition, when a negative dry film is used as a film for fixing the said board | substrate material to the said jig | tool, a positive type thing is used as a resist used here. This is because dissolution of the film in the developer used in this step can be prevented.

H, other

Since what has the function as a printed wiring board is manufactured by the process to here, a printed wiring board can be obtained by cutting | disconnecting to a desired size after that, but if it is necessary to form bumps on the said printed wiring board, before cutting, Resist coating, exposure and development (expose the bump formation points in the conductor pattern), bump formation (plating using a solution containing gold ions may be sufficient. In addition, since bumps require a certain height, copper is first used. Alternatively, a base made of nickel or the like may be formed and gold plating may be performed only on the surface layer of the base), or a series of operations such as peeling and removing the resist may be performed, or the solder ball may be deposited at a predetermined position according to a usual method. .

Although description has been made as a case of newly forming a conductor pattern on the substrate, the feature of the manufacturing method using the jig of the present invention is attributable to its thinness even in a very thin substrate (silicon wafer) of which there is no conventional example. It is a matter of course that the present invention can be applied to a case in which a conductor pattern is already formed on a substrate, for example, a case in which only a bump is formed in a circuit-formed IC. In that regard, in conventional IC manufacturing, a method of forming bumps after physically grinding the back surface of a thick substrate (silicon wafer) to a desired thickness (a substrate that forms bumps is of course poor in handling). After the bumps are formed on a thick substrate (silicon wafer), a method of grinding the back surface of the substrate to a desired thickness by dry etching or the like (a considerable cost is required for installing a Torai etching facility) has been applied.

Example

Using 8-inch silicon wafers (thickness: 20 µm; nominal diameter 200 mm), 20 printed wiring boards were manufactured by the following method.

1. Jig for supporting substrate material

Jig (specific state is shown in Fig. 3) using the following specifications.

Length: 230 mm;

Width: 230mm;

Thickness: 1mm;

Opening diameter 196 mm;

End width: 2 mm;

· Formation range of end: whole circumference;

Slope of upper slope: about 7.6 °                 

Lower slope: about 4.6 °

2. film cloth

Both surfaces of the silicon wiper placed on the end of the above jig were coated with a dry film (NIT315 manufactured by Nichigo Moton Co., Ltd .; thickness 15 μm) using a vacuum laminator (CVA MODEL 725 manufactured by Nichigo Moton Co., Ltd.) for each jig. The silicon wafer was tightly fixed to the jig, and then the coated dry film was exposed and developed according to a usual method, and a work area (both sides) having a diameter of 190 mm was secured on the silicon wafer.

3. Formation of Through Hole

Ten through holes (100 micrometers in diameter) were formed in the silicon wiper in the said work area by the wet etching method.

4. Formation of Metal Thin Film-1

A metal thin film-1 (ITO; thickness: 100 kPa) was formed on a silicon wafer (both sides, including the inner wall of the through hole) in the work area using a sputtering apparatus (SH-450 manufactured by JK Corporation). : 1 page).

In addition, the metal thin film-1 (Ni + Au; thickness: 0.5 mu m) was also formed by the electroless plating method (mel plate Ni-867M1 to M2 and Au-601 manufactured by Meltex) (number of wafers: 1 sheet) ).

5. Formation of Metal Thin Film-2

By the electroless plating method (using Cu Posit 251 manufactured by Sipure Fyist Co., Ltd.), metal thin film-2 (Cu; thickness: 20 mu m) was formed again on the metal thin film-1 previously formed by sputtering.

6. Formation of conductor pattern

A resist (Posiform Resist, SPR-6800, manufactured by Sipure Fist) was applied onto the metal thin film-2 phase and the metal thin film-1 formed only by the electroless plating method, followed by exposure, development, etching and resist stripping. A wiring pattern was formed on the silicon wafer (both sides). In addition, the detailed tips are as follows.

Use coater: Hirata Engineering Co., Ltd. slot coater (α coater)

Resist coating thickness: 10 mu m (after drying: 3 mu m)

Mask pattern: L / S of 3㎛ is used

Exposure light source: 200Φ PROJ-2001 manufactured by Mejiro Investment Co., Ltd.

Etching liquid: V Post Etch 746 made by Shipure Fist

Peeling Liquid: Remover 1177A

7. The formation of bumps

A resist (positive resist: SPR-6800 manufactured by Sipure Pyist Corporation) was applied, followed by exposure, development, electroplating, and resist stripping to form gold bumps on the bump lands of the wiring patterns. In addition, the detailed tips are as follows.

· Coater used: Slot coater (α coater) manufactured by Hirata Corporation. Slot direction is the radial direction of the substrate.

Resist coating thickness: 10㎛

Mask pattern: bump land diameter of 100㎛Φ and 200㎛Φ                 

Exposure light source: uses 200Φ PR0J-2001 manufactured by Mejiro Investment Co., Ltd.

Plating solution: Evalon Ni BM-2 (for the bottom) and Aurore Lostless SMT250 (gold-plated) from Reronal Corporation are used, respectively.

Peeling Liquid: Remover 1177A

8. Dicing

Based on conventional IC wafer dicing.

When the completed printed wiring board (20 mm x 20 mm) was laminated | stacked five layers in the up-down direction, and it energized, conduction to all the wiring boards was confirmed.

As mentioned above, according to this invention, the manufacturing method of the printed wiring board which can manufacture the ultra-thin printed circuit board which can be multi-stacked laminated | stacked matched the requirements of the thickness of a board | substrate and electrical characteristics can be provided.

Claims (13)

A. preparing a silicon wafer having a thickness of 50 µm to 300 µm; B. attaching the silicon wafer to a jig capable of supporting only its periphery, covering the entire surface with a film to fix the silicon wafer to the jig; C. patterning the film to expose a silicon wafer front and back surface; D. forming a through hole at a predetermined position of the exposed silicon wafer and forming a metal thin film on an exposed surface of the silicon wafer including the through hole; And E. A method for manufacturing a printed wiring board, comprising: patterning the metal thin film, followed by etching to obtain a predetermined conductor pattern. The method of claim 1, After the formation of the conductor pattern described above, a resist is applied and patterned again, and then a bump is formed by performing gold plating with copper or nickel as a base layer at a predetermined position on the conductor pattern. Way. The method of claim 1, Said silicon wafer has a surface roughness of 1000 GPa-5000 GPa, The manufacturing method of the printed wiring board characterized by the above-mentioned. The method of claim 1, The said film is a negative dry film, and the resist used for patterning the said metal thin film is a positive type, The manufacturing method of the printed wiring board characterized by the above-mentioned. The method of claim 1, The method for producing a printed wiring board, wherein the metal thin film is formed by vapor deposition, electroless Cu plating, or electroless Ni-Au plating. delete The method of claim 1, The above-mentioned formation of the through hole is performed by a laser drilling method, a plasma etching method, or a photolithography method. A rectangular or circular jig for producing a printed wiring board made of silicon having an opening in the center thereof and an end portion in which the periphery of the silicon wafer can be placed near the opening, The end portion is formed such that the central axis in the thickness direction of the jig and the central axis in the thickness direction of the silicon wafer are coaxial, The jig has a horizontal upper surface and a lower surface, and a straight lower slope which rises from the lower surface toward the inner circumferential end of the horizontal surface of the end portion and an inclination from the upper surface toward the upper end of the wall surface of the end portion or the lower slope. As having a straight upper slope going down, Grooves in the upper and lower surfaces and the upper and lower slopes in the radial direction of the opening, the starting end of which is the upper and lower ends of the outer circumferential end and the upper end of the wall or the end of the upper slope; A jig for manufacturing a printed wiring board made of silicon, comprising a plurality of grooves that are front ends of the horizontal surfaces of the ends. The method of claim 8, Jig for producing a printed wiring board made of silicon, characterized in that the jig consists of one member. The method of claim 8, The jig consists of two upper and lower members which abut on the lower and upper surfaces thereof, the end portions are formed on each member, and the periphery of the silicon wafer is sandwiched between the horizontal surfaces of both ends. A jig for producing a printed wiring board made of silicon, characterized in that the central axis in the thickness direction of the jig is abutting surface of those members, and the slope of the upper member descends toward the distal end of the horizontal plane of the end of the upper member. The method of claim 8, The jig consists of two members, upper and lower, which fit on their lower and upper surfaces, the end is formed only on the lower member, and the placement of the periphery of the silicon wafer is based on the horizontal surface of the end and the upper member. It is a pinch by the horizontal surface which is a lower surface, and the center axis of the thickness direction of the said jig | tool is at the position which descended to the member side below 1/2 of the thickness of the board | substrate from the contact surface of those members, and the slope of the upper member is the lower side Jig for manufacturing a printed wiring board made of silicon, characterized in that it is lowered as a slope such as a slope of a member. The method of claim 9, The inclination of the upper slope is the same as the inclination of the lower slope, but the tip ends at the upper end of the wall portion of the end portion, and the depth of the wall portion of the end portion is larger than the thickness of the silicon wafer described above, and corresponds to the difference. And a pressing member having an outer circumferential thickness and an inclined slope, such as the upper slope, above and below a horizontal plane opposite the horizontal plane of the end, wherein the placement of the periphery of the silicon wafer is characterized by the horizontal plane of the end and the; Jig for manufacturing a printed wiring board made of silicon, characterized by a pincer with a horizontal surface of the pressing member. The method according to any one of claims 1 to 5 and 7, The jig used in step B is a jig according to any one of claims 8 to 12. A method for producing a printed wiring board

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