CN216414687U - Two-stage photopolymerisation device for photopolymerisation layers of printed circuit boards - Google Patents

Abstract

The application provides a second-order illumination polymerization device, which comprises a moving platform, a digital micro-mirror device, a UV light source, a photomask and a mercury lamp. The transfer platform is used for carrying a printed circuit board with a top surface provided with a photo-polymerization layer, is preset in the first working area, and transfers the carried printed circuit board to the third working area through the second working area when the transfer platform works. The digital micro-mirror device and the UV light source are arranged in the second working area, the UV light source is used for illuminating the light polymerization layer for the first time through the digital micro-mirror device in the process that the transfer platform passes through the second working area, and the power of the UV light source is less than 0.2 kW. The light shield is used for covering the transfer platform when the transfer platform moves to the third working area and contacting the photopolymerization layer with the bottom surface of the light shield, the mercury lamp is arranged in the third working area and used for irradiating the photopolymerization layer for the second time through the light shield, and the power of the mercury lamp is more than 5 kW.

Description

Two-stage photopolymerisation device for photopolymerisation layers of printed circuit boards

Technical Field

The present disclosure relates to a patterning device for a photo-polymerization layer in a printed circuit board, and more particularly, to a device for improving the yield of photo-polymerization process by providing different light sources.

Background

Printed circuit boards typically have multiple layers of insulating material and multiple layers of circuitry, wherein a portion of the insulating material and the photoresist layer used to pattern the copper foil into the circuitry may be made of photopolymerizable material (in the form of photopolymerizable layers) that can be patterned by exposure and development.

The conventional photo-polymerization layer is patterned by covering a photomask and then irradiating, but because the photo-polymerization layer is in an uncured or semi-cured state before irradiation, particles in the environment may be contaminated at the position originally required to be irradiated when the photomask is covered, so that the area originally required to be irradiated is shielded by the particles and is not irradiated, and a plurality of unnecessary pores are formed in the photo-polymerization layer in the subsequent developing process. In addition, when the mask is covered with the photopolymerizable layer, the mask itself may be damaged by the photopolymerizable layer. That is, the problem of the prior art is that the use of the mask adversely affects the yield of the patterning process for the reasons mentioned above.

On the other hand, Maskless Lithography (mask Lithography) technology is gradually becoming a trend of improvement, in which a Digital Micromirror Device (DMD) is used in combination with a UV light source to perform Direct write Digital Imaging (DI), so that the irradiation range can be controlled by the DMD without using a mask, thereby performing a patterning process on a photo-polymerization layer. Nevertheless, the above-mentioned DMD with UV light source has the obvious disadvantage that the power of the UV light source cannot be too high because the DMD cannot bear too high energy (otherwise, the load of the heat sink may be exceeded), and the UV light source must supply energy to the photopolymerizable layer in a low-power and high-frequency manner in order to provide the energy required for the polymerization of the photopolymerizable layer; however, if the thickness of the photopolymerizable layer is large (e.g., solder mask), or even if the photopolymerizable layer is colored (lower transmittance), the low power UV light will hardly reach the bottom of the photopolymerizable layer, causing insufficient bottom curing, and thus causing very severe inward rotation (over cut) at the edge of the development and windowing in the subsequent development and windowing.

It would therefore be desirable to those skilled in the art to solve, or at least alleviate, all of the above problems.

SUMMERY OF THE UTILITY MODEL

The present application provides an apparatus for processing a thick photo-polymerization layer, which can solve the problem that the mask is liable to adversely affect the yield of the patterning process.

In order to achieve the above objects, the present application provides a dual stage photo-polymerization apparatus for photo-polymerization of printed circuit boards, which comprises a first working area, a second working area, a third working area, at least one transfer platform, a digital micro-mirror device, a UV light source, at least one mask and a mercury lamp. The transfer platform is used for carrying a printed circuit board with a top surface provided with a photo-polymerization layer, is preset in the first working area, and transfers the carried printed circuit board to the third working area through the second working area when the transfer platform works. The digital micro-mirror device and the UV light source are arranged in the second working area, the UV light source is used for illuminating the light polymerization layer for the first time through the digital micro-mirror device in the process that the transfer platform passes through the second working area, and the power of the UV light source is less than 0.2 kW. The light cover is used for covering the transfer platform when the transfer platform moves to the third working area and the bottom surface of the light cover is contacted with the photopolymerization layer, the mercury lamp is arranged in the third working area, the mercury lamp is used for irradiating the photopolymerization layer for the second time through the light cover after the light cover covers the photopolymerization layer, and the power of the mercury lamp is more than 5 kW.

Applicants have found that the photopolymerizable layer has the property of starting to cure from the top when first illuminated with a low power UV light source, while the dmd does not need to contact the photopolymerizable layer and does not have the problems of particle contamination and crushing of the uncured/semi-cured photopolymerizable layer. Then, when the mercury lamp is irradiated for the second time, the mercury lamp has high power enough to completely cure the bottom of the photopolymerizable layer even with a large thickness, and since the top of the photopolymerizable layer is already cured by the first irradiation before the second irradiation, even if the particles are adhered to the position originally subjected to the second irradiation, the small holes are not formed in the subsequent development process (the top of the cured photopolymerizable layer can be protected), and the top of the cured photopolymerizable layer is not damaged by pressure, thereby solving the long-standing problem of the conventional patterning process through a photomask. Thus, the present application can be a good photopolymer patterning processing apparatus, especially for processing of solder masks of generally thicker thickness, and also in the trend of mask-less lithography, the counter potential provides another cost-effective option.

Other features and embodiments of the present application will be described in detail below with reference to the drawings.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic view of a second order illumination polymerization apparatus according to a first embodiment of the present application;

FIG. 2 is a schematic side view of a second illumination polymerization apparatus according to a first embodiment of the present application, in which some components are omitted;

fig. 3 to 5 are schematic views illustrating the operation of the second order illumination polymerization apparatus according to the first embodiment of the present application;

FIG. 6 is a schematic side view of a second embodiment of the second illumination polymerization apparatus, wherein some components are omitted.

Description of the symbols

1: photopolymerizable layer 2: printed circuit board 10: load transferring platform

20: digital micromirror device 30: the UV light source 40: light shield

50: mercury lamp S1: first operating region S2: second working area

S3: a third working area

Detailed Description

The positional relationship described in the following embodiments includes: the top, bottom, left and right, unless otherwise indicated, are based on the orientation of the elements in the drawings.

Referring to fig. 1 and 2, a first embodiment of a two-stage photo polymerization apparatus for photo polymerization of a photo polymerization layer of a printed circuit board for patterning the photo polymerization layer is illustrated. The Printed Circuit Board may be a single-layer Board structure or a multi-layer composite Board structure, and may be a carrier of a Flexible Printed Circuit (FPC) or a carrier of a rigid Printed Circuit Board (PCB), and the used material may be, but is not limited to, polyethylene terephthalate (PET) or other polyester films, polyimide films, polyamide-imide films, polypropylene films, and polystyrene films. The photopolymerizable layer is a layer formed of a photopolymer (photopolymer) which is polymerized by irradiation with light and then cured, and possible photopolymerizable layers are, for example, a photoresist layer required for patterning a copper foil or a dielectric layer of a printed circuit board, such as an opaque solder resist ink. The second stage illumination polymerization apparatus of the present embodiment includes a first working space S1, a second working space S2, a third working space S3, a transfer platform 10, a digital micromirror device 20, a UV light source 30, a mask 40 and a mercury lamp 50.

The transfer platform 10 is used for carrying the printed circuit board 2 having the photopolymerizable layer 1 on the top surface, the transfer platform 10 is preset in the first working area S1, and when the transfer platform 10 is located in the first working area S1, the printed circuit board 2 can be moved to the transfer platform 10 by a human or an automated device. When the transfer platform 10 is operated, the loaded printed circuit board 1 can be moved to the third working area S3 through the second working area S2 by a screw mechanism or other displacement mechanism. In a possible embodiment, after the photo-polymerization layer 1 is photo-polymerized, the transfer platform 10 returns to the first working area S1, and the printed circuit board 2 is removed from the transfer platform 10 by using a manual or automatic device.

The dmd 20 is disposed in the second working area S2, the dmd 20 has a plurality of micro-mirrors, and the micro-mirrors are turned over by a control signal to form a fast digital optical switch, which can control whether light can pass through the dmd 20, so as to have a function of performing a photo-polymerization process on the photo-polymerization layer 1.

The UV light source 30 is also disposed in the second working area S2, and has a plurality of UV lamps capable of exciting the photopolymer to polymerize, which may damage the dmd 20 when the power of the UV light source is high, so the power of the UV light source is less than 0.2kW, or even less than 0.1 kW. The UV light source 30 can illuminate the photo-polymerization layer 1 for the first time through the dmd 20 during the process that the transfer platform 10 passes through the second working area S2.

The mask 40 is used to cover and contact the photopolymerizable layer 1 with its bottom surface when the transfer platform 10 moves to the third working area S3. The mask 40 may be placed within a mask frame and displaced by automated equipment. In a possible embodiment, different masks 40 may be selected for use, depending on the shrinkage of different printed circuit boards or for other considerations, and replacement of the masks may be done manually or by automated equipment.

The mercury lamp 50 is provided in the third working space S3, and irradiates the photopolymerizable layer 1 with light through the mask 40 for a second time after the mask 40 covers the photopolymerizable layer 1. In the present application, the mercury lamp 50 has a power of more than 5kW, and ensures sufficient illumination of the bottom of the photopolymerizable layer 1.

The second order photopolymerization process of the present application is described below:

firstly, providing a printed circuit board 2 with a top surface provided with a photopolymerizing layer 1, wherein the photopolymerizing layer 1 can be formed by directly coating photopolymerizing material slurry on the printed circuit board 2, or the photopolymerizing material can be made into a dry film form and then laminated on the top surface of the printed circuit board 2 to form the photopolymerizing layer 1; after the formation of the photopolymerizable layer 1, the printed circuit board 2 may be moved by a manual or automated device to the transfer platform 10 located at the first working area S1, as shown in fig. 3;

next, as shown in fig. 4, the transfer platform 10 is moved from the first working area S1 to the second working area S2, and the photo-polymerization layer 1 is irradiated with light by the UV light source 30 through the digital micro-mirror device 20 for the first time, wherein the energy provided by the UV light source 30 during the first light irradiation is less than the irradiation energy required for the complete curing of the photo-polymerization layer 1, and preferably, the energy provided by the UV light source 30 during the first light irradiation is less than half of the irradiation energy required for the complete curing of the photo-polymerization layer 1, so as to reduce the processing time of the first light irradiation; after the first illumination, at least the top of the photopolymerizable layer may be cured;

then, the first illumination is stopped, and the transfer platform 10 continues to move to the third working area S3;

next, as shown in fig. 5, the photopolymerizable layer 1 is covered with a mask 40, and the bottom surface of the mask 40 contacts the photopolymerizable layer 1; since the top surface of the photopolymerizable layer 1 has been cured after the first illumination, it is not damaged by the mask 40, and no particles of the photopolymerizable layer 1 stick to the mask 40;

finally, the photopolymerizable layer 1 is irradiated with light for the second time through the mask 40 by the mercury lamp 50, the energy supplied by the mercury lamp 50 in the second irradiation is not less than the irradiation energy required for complete curing of the photopolymerizable layer 4 minus the energy supplied by the first irradiation, and since the power of the mercury lamp 50 exceeds 5kW, even the photopolymer at the bottom of the photopolymerizable layer 1 can be completely cured (even at the bottom of the photopolymerizable layer 1 having a maximum thickness of not less than 20 μm), so that the problem of serious inward rotation when the photopolymerizable layer 1 is subsequently developed and windowed can be avoided. In a possible embodiment, it is also possible for the printed circuit board 2 to be removed in the third operating area S3 after the second illumination has been carried out.

In addition, referring to fig. 6, a second embodiment of the dual stage illumination polymerization apparatus is illustrated, which is different from the first embodiment in that it has two transfer platforms 10, and when one of the transfer platforms 10 moves in the second to third work areas, the other transfer platform can continue to move in and out another pcb, and the two stages can alternately transport pcbs in the first to third work areas.

The above-described embodiments and/or implementations are only for illustrating the preferred embodiments and/or implementations of the technology of the present application, and are not intended to limit the implementations of the technology of the present application in any way, and those skilled in the art can make modifications or changes to other equivalent embodiments without departing from the scope of the technology disclosed in the present application, but should be construed as technology or implementations substantially the same as the present application.

Claims (2)

1. A two stage photopolymerisation apparatus for photopolymerising layers of printed circuit boards, comprising:

a first working area;

a second working area;

a third working area;

at least one transfer platform for carrying a printed circuit board with a top surface provided with a photopolymerization layer, wherein the transfer platform is preset in the first working area and is used for transferring the carried printed circuit board to the third working area through the second working area during working;

a digital micro-mirror device arranged in the second working area;

the UV light source is arranged in the second working area and used for irradiating the photopolymerization layer for the first time through the digital micromirror device in the process that the transfer platform passes through the second working area, and the power of the UV light source is less than 0.2 kW;

at least one photomask, which is used for covering and contacting the photopolymerization layer by the bottom surface when the transfer platform moves to the third working area; and

and the mercury lamp is arranged in the third working area and used for irradiating the photo-polymerization layer for the second time through the photomask after the photomask covers the photo-polymerization layer, and the power of the mercury lamp is more than 5 kW.

2. The apparatus of claim 1, wherein the UV light source has a power of less than 0.1 kW.

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