TWM571105U - Circuit board structure with laser windowing area - Google Patents

Abstract

A circuit board structure includes a carrier board, a circuit layer and a solder resist layer, and the circuit layer is disposed on the carrier board The solder resist layer is disposed on the circuit layer and the carrier, and the solder resist layer has at least one laser window opening to expose at least a portion of the circuit layer.

Description

Circuit board structure with laser windowing area

The present invention relates to a circuit board structure, and more particularly to a circuit board structure having a laser window opening.

Conventional circuit board structures usually form a solder mask on the metal circuit layer, covering the circuit and metal surface that are not to be soldered, thereby preventing short circuit during soldering and saving soldering amount; on the other hand, solder resist layer It can prevent moisture and electrolyte from entering the circuit board, avoiding oxidation of the circuit layer and damaging electrical properties, and preventing the device from damaging the circuit layer. On the other hand, since the line width of the circuit layer on the circuit board is narrower and narrower, The solder layer also provides insulation between adjacent circuits.

Next, using a development etch process, the solder resist layer on the designated solder joint of the circuit layer is removed, exposing the circuit layer of the solder joint for subsequent soldering processes. The development etching process utilizes irradiation of a specific wavelength band of UV light or visible light onto the solder resist layer to cure the solder resist layer; then removing the uncured solder resist layer material with a special chemical solvent to make the solder joint The circuit layer is exposed. However, when the solder resist layer is cured by light, since the reflectance and thickness of the solder resist layer affect the transmittance of UV light or visible light, the solder resist material at the bottom of the solder resist layer is not completely cured and is removed by a special chemical solvent. . In this way, the circuit layer that should be protected by the solder resist layer will be exposed, and when the subsequent soldering process is performed, it is likely to cause a short circuit or even damage the circuit board.

Therefore, how to provide a circuit board structure that can accurately open a window at a solder joint is an urgent technical problem to be solved.

In view of this, the main object of the present invention is to provide a circuit board structure in which the solder resist layer has a laser window opening area for accurately exposing a predetermined exposed circuit layer.

In order to achieve the above object, the present invention provides a circuit board structure including a carrier board, a circuit layer and a solder resist layer. The circuit layer is disposed on the carrier board; the solder resist layer is disposed on the circuit layer and the carrier board, and the solder resist layer has at least one laser window opening area to expose at least a portion of the circuit layer.

In the present embodiment, the solder resist layer has a thickness of 10 to 200 μm.

In the present embodiment, the solder resist layer has a thickness of 10 to 50 μm.

In the novel embodiment, the solder resist has a light reflectance of at least a portion of the wavelength in the visible wavelength range of greater than 80%.

In the present invention, the solder resist has a light reflectance of greater than 80% for visible light having a wavelength of at least a portion of the wavelength in the range of 625-740 nm.

In the novel embodiment, the solder resist has a light reflectance of greater than 80% for visible light having a wavelength of at least a portion of the wavelength in the range of 500-565 nm.

In the novel embodiment, the solder resist has a light reflectance of greater than 80% for visible light having a wavelength of at least a portion of the wavelength in the range of 485-500 nm.

Based on the above design, the circuit board structure of the present invention can accurately remove the solder resist layer on the specified solder joint due to the laser window opening area, and does not remove the solder resist material outside the laser window opening area to prevent The subsequent soldering process has a short circuit problem.

In order to explain the present invention more clearly, it will be described in detail with reference to the preferred embodiments and drawings. Referring to FIGS. 1A and 1B, the circuit board structure 10 of the present embodiment includes a carrier 12, a circuit layer 14, and a solder resist layer 16. In this embodiment, the carrier 12 can be a single-layer board structure or a multi-layer composite board structure, and the carrier board 12 can be a flexible printed circuit (FPC) carrier board or a printed circuit board (PCB). The carrier board 12 may be polyethylene terephthalate (PET) or other polyester film, polyimine film, polyamidimide film, polypropylene film, polystyrene film, etc. .

As shown in FIGS. 1B and 3A, the circuit layer 14 is provided on the carrier 12. In this embodiment, the circuit layer 14 is laminated on the carrier 12, which is formed with a thin copper foil (not shown) and then plated with copper to form a copper conductive layer on the carrier 12 (not shown). . Next, the copper conductive layer is imaged by a line image transfer technique to form a circuit layer 14 on the carrier 12 (as shown in FIG. 1B). In the present embodiment, the material of the circuit layer 14 includes copper.

Next, as shown in FIG. 3B, the solder resist layer 16 is provided on the circuit layer 14 and the carrier 12. In this embodiment, the material of the solder resist layer 16 may be, for example, a double-layer type solder mask ink of a thermosetting solder resist ink or a photo-curable solder resist ink type, and the composition thereof includes, for example, a solder resist main agent. Colorants, thinners and hardeners (Hardener).

The solder resist main agent of the embodiment mainly comprises a photoimageable solder resist resin, and the photoimageable solder resist resin can be: a carboxyl group-containing photoimageable resin, a carboxyl group-containing photoimageable resin combined with an epoxy resin or a combination of thermosetting properties. A carboxyl group-containing photoimageable resin of a resin or a photocurable resin. On the other hand, the solder resist main agent may contain other additives conventional in the field of electronic materials in addition to the photoimageable solder resist resin, such as organic solvents, antioxidants, fillers, dispersants, plasticizers, antistatic agents. Agent, anti-aging agent, ultraviolet absorber, antifoaming agent, thermal polymerization inhibitor, coupling agent, flame retardant, anti-fungal agent, flat agent, tackifier, release agent, surface modifier, stabilizer. In practice, the material of the solder resist main agent may also include an epoxy resin, a enamel resin, a polyimide resin, a phenol resin, a fluororesin, cerium oxide or aluminum oxide.

The coloring agent of this embodiment is, for example, a white coloring agent, so that after curing, the solder resist layer 16 has a light reflectance of at least a portion of the wavelength in the visible light wavelength range of more than 80%, wherein the visible light wavelength is between 485 nm and Between 740 nm, between 625 nm and 740 nm, between 500 nm and 565 nm, or between 485 nm and 500 nm. The diluent of this embodiment is used to adjust the viscosity of the material of the solder resist layer 16 so that the solder resist layer 16 can be uniformly formed on the carrier 12 and the circuit layer 14. The hardener of the present embodiment may include at least one of a photopolymerization initiator, a hardening aid, and a hardening catalyst. In the present embodiment, the solder resist layer has a thickness of 10 to 200 μm, preferably 10 to 50 μm.

Next, as shown in FIG. 3B, a laser windowing region 16 is formed at the solder resist layer 16 corresponding to the position of the circuit layer 14 to expose a portion of the circuit layer 14 by a laser windowing technique. The laser windowing technique of the present embodiment utilizes the laser windowing device 30 to provide a laser beam L of a specific energy, and the material in the designated window opening region 164 on the solder resist layer 16 is prevented from being ashed and removed to obtain a predetermined size. The solder mask layer 16 has a window opening region 162 as shown in FIGS. 1A and 1B. By the laser windowing technology, the size of the window opening region 162 of the solder resist layer 16 on the circuit board structure 10 can be precisely controlled, and the risk of excessively removing the material of the solder resist layer 16 can be reduced to reduce the influence on the circuit board structure 10. Electrical properties.

Referring to Figures 2A and 2B, a circuit board structure 20 of another embodiment of the present invention is provided. The circuit board structure 20 includes a carrier 22, a circuit layer 24, and a solder resist layer 26. It should be noted that the constituent materials of the circuit board structure 20 are substantially similar to the constituent materials of the circuit board structure 10, but the difference between the two is that the size of the laser window opening area of the solder resist layer is different. In the circuit board structure 10, since the laser window opening region 162 is small, the solder resist layer 16 still covers part of the circuit layer 16, as shown in FIG. 1B; and in the circuit board structure 20, the laser is turned on. The window region 262 is relatively large such that in the laser windowing region 262, the solder mask 26 is not overlying the circuit layer 26 and a portion of the carrier 22 is exposed.

Based on the above design, the circuit board structure of the present invention can accurately remove the solder resist layer on the specified solder joint due to the laser window opening area, and does not remove the solder resist material outside the laser window opening area to prevent The subsequent soldering process has a short circuit problem.

10, 20‧‧‧ circuit board structure

12, 22‧‧‧ carrier board

14, 24‧‧‧ circuit layer

16, 26‧‧‧ solder mask

162, 262‧ ‧ laser window opening area

164‧‧‧Designated window area

30‧‧‧Laser window opening equipment

L‧‧‧Laser beam

Fig. 1A is a plan view showing the structure of the circuit board of the first embodiment of the present invention.

Fig. 1B is a cross-sectional view of Fig. 1A.

Fig. 2A is a plan view showing the structure of the circuit board of the second embodiment of the present invention.

Figure 2B is a cross-sectional view of Figure 2A.

3A, 3B, and 3C are cross-sectional views showing process steps of the circuit board structure of the first embodiment of the present invention.

Claims (7)

A circuit board structure having a laser window opening region, comprising: a carrier board; a circuit layer disposed on the carrier board; and a solder resist layer disposed on the circuit layer and the carrier board, and the solder resist The layer has at least one laser windowing region to expose at least a portion of the circuit layer. A circuit board structure having a laser window opening region as claimed in claim 1, wherein the solder resist layer has a thickness of 10 to 200 μm. A circuit board structure having a laser window opening region as claimed in claim 1, wherein the solder resist layer has a thickness of 10 to 50 μm. A circuit board structure having a laser windowing region according to claim 1, wherein the solder resist layer has a light reflectance of at least a portion of the wavelength in the visible light wavelength range of greater than 80%. A circuit board structure having a laser windowing region according to claim 1, wherein the solder resist layer has a light reflectance of greater than 80% for visible light having a wavelength of at least a portion of a wavelength in the range of 625-740 nm. A circuit board structure having a laser windowing region according to claim 1, wherein the solder resist layer has a light reflectance of at least 80% for visible light having a wavelength of at least a portion of a wavelength in the range of 500-565 nm. A circuit board structure having a laser windowing region according to claim 1, wherein the solder resist layer has a light reflectance of greater than 80% for visible light having a wavelength of at least a portion of the wavelength in the range of 485-500 nm.