Abstract: In order to meet customer requirements, on-hole must Cypriot hole, after a lot of practice, we change the traditional Cypriot Al-technology, complete with white-board network with the Cypriot Solder Mask hole. Production stable, reliable quality.

Key words: on-hole-Cypriot and Cypriot-Solder Mask

Via hole also known as conductive hole, guided through holes, starting on-line link between the role. The development of the electronics industry, but also promote the development of PCB, the PCB production of surface-mount technology and higher demands. Via hole Cypriot-technology came into being, and should meet the following requirements:
(1) on-hole can be a copper, Solder Mask may from time to Cypriot Cypriot;
(B) on-hole must have a tin-lead, have a certain thickness requirements (4 microns), are prohibited Solder Mask ink into the hole, resulting in tin-containing beads;
(C) on-hole must have Solder Mask ink-Cypriots, not translucent, may not have tin laps, tin-and the formation requirements. (See diagram below)

First, line-opacity
Second, we must build on-hole oil
Third, a covered oil, to be on the other side of Sn / Pb allow a tin-and-circle as the electronic products to the "light, thin, short, small" direction, PCB also to the high-density, difficult development, a large number of SMT, BGA of the PCB, and customers in the mount components at the request Cypriot hole, there are five main roles:
(A) prevent the PCB during the wave soldering tin from the on-hole through components of the short circuit;
(B) to avoid flux residues in the on-hole;
(C) electronic components and factory surface-mount PCB assembly after the completion of the testing of aircraft to a suction vacuum suction to complete:
(D) to prevent the surface Paste into the hole caused by Xu Han, the impact mount;
(5), to prevent a wave soldering tin-pop, causing short-circuit. The surface-mount board, in particular, BGA and the mount of the IC-Cypriot-on-demand to be formed, Tuao plus or minus 1 MIL, may be on-edge-on-red;-on-tin-possession, in order to reach customers The requirements of on-Cypriot-hole technology is varied, particularly long process, process control difficult, often in a hot air leveling and oil-resistant green solder experiments swap oil; curing the problem occurred after the explosion oil. On the basis of the actual production conditions, the various PCB-Cypriot technology into the process and the advantages and disadvantages for some and on:

After the hot air of a whole-of-Cypriots

This process is: Solder Mask board → HAL → Cypriot-→ curing. The use of non-Cypriot-production process, hot air the whole network Al-later version of Mexico or block network to complete all the requirements of customers on-the fortress-Cypriot hole. Cypriot-ink can be used photographic ink or thermosetting ink, to ensure consistent color film wet circumstances, the best use of ink-Cypriots and the board of the same ink. This process can guarantee that the entire air-hole lead after the oil can not, but the Cypriot-ink-pollution board, not formed (see diagram below). When customers mount easily cause Xu Han (especially BGA). So many customers do not accept this method.

The hot air leveling of the former Cypriot -

2.1 with Al-Cypriots, curing, grinding plate after the transfer of this process graphics with CNC drilling, drilled the Al-Cypriots to be transformed into Screen, a Cypriot hole, and ensure on-hole full-Cypriots, Cyprus Ink-Cypriot-ink, ink can also be used thermosetting, its characteristics must hardness, resin contraction of small changes, combined with the hole in the wall good. Process:

Pre-treatment → Cypriot-→ grinding plate → graphics transfer → etching → board Solder Mask
Al Screen
With this method can guarantee that on-Cypriot-hole formation, the whole air-there will be no blasting oil, oil-side out quality problems, but this one-time requirements of thickening of copper, so that the hole wall thickness of copper to customers and, therefore, Copper plating on the whole board demanding, and the grinding plates of the high performance requirements to ensure that the copper surface, and so completely removed from the resin, copper surface clean and not contaminated. Many PCB plant not a one-time thickening copper technology, equipment and the performance of达不到要求, resulting in this process in the use of small PCB plant.

2.2 with Al-Cypriot silk screen directly after the board Solder Mask

CNC drilling machine with this process, to be drilled the Al-Cypriots, made net version, in silk screen machines installed on the Cypriot hole, hole after the completion of UNAMSIL shall not be parked more than 30 minutes, with 36 T-screen direct silk screen panels Solder Mask, for the process:
Pre-treatment - Cypriot hole - silk screen - pre-bake - a contrast exposure - curing
Al Screen Screen
Use this process to ensure on-hole covered oil, and Cypriot hole formation, the same color film wet, hot air leveling after not guarantee on-the-hole, hole-not-possession, but easy for the ink on the hole after curing Pads, can be caused by welding ill; Hot Air-hole edge after the on-foaming swap oil, used this method of production control more difficult to process engineering staff using special processes and parameters to ensure the quality of Cypriot hole.

2.3 Al-Cypriots, developing, pre-curing, grinding plate after plate of Solder Mask.

With CNC drilling, drilled the Al-Cypriot demands, made net edition, silk screen machines installed in the shift on the Cypriot hole, must be full-Cypriots on both sides highlighted better, and then after curing, grinding plate to deal with board , The process is:
Pre-treatment - a pre-bake-Cypriots - Developers - Pre-curing - board Solder Mask
Al Screen
As the use of Cypriot-curing process can be guaranteed after the through-hole HAL can not oil, oil explosion, but HAL, the through-hole of tin-and on-the-hole difficult to solve, so many customers not to receive.

Solder Mask 2.4 board and Cypriot hole at the same time.

This method used 36 T (43T) of the screen, installed in the silk screen on the plane, used Dianban or nail bed, and the completion of the board at the same time, all on-the-gagged, their process:
Nail bed
Pre-treatment - silk screen - pre-exposure bake January 1 January 1 January 1 image Curing
Network is ready
This process short time, the utilization rate of equipment, to ensure that the entire air-after a hole can not oil, not on-the-hole, but because of a silk screen to Cypriot hole, a hole in the memory a large number of air, in the curing , The expansion of the air, breaking the Solder Mask film, resulting in empty, not formation, there will be a small amount of hot air the whole-on-tin-possession. At present, our company through a large number of experiments, the choice of different types of ink and viscosity, the pressure adjustment silk screen, basically solved through-hole and not empty formation, have adopted this technology production.

As different processes have different technology requirements, production conditions and equipment needs, and each has advantages and disadvantages, for my company Cypriot orifice and a board Solder Mask Cypriot hole at the same time, production stable, reliable, is the control on the wet film Skills and make some simple description:
(A) ink prepared
Solder Mask board for use on-demand ink-Cypriot hole, the choice of ink on a relatively small, with the last few years the rapid development of photosensitive materials, the market more and more sensitive type of ink. Ink hardening agent component of more than 30 percent, solid ingredients should be accounted for 78 percent, small changes in resin contraction, is conducive to Cypriot hole, the longer development time, undercut smaller, and ensure a clean image ink hole components. Kai oil, viscosity should be in control of more than 220 PS (22 soil temperature is 2 ℃, humidity of 60 soil 5% RH). Add the oil and water as a control in the 15 CC / KG, the use of suppliers to provide dedicated thinner.
(B) tools ready
1) Dianban production: NC drilling 2.0 mm mouth of the drill hole drilling and on-the same plate, use the 1.0-l.4 mm CCL (to trim), Dianban to rule out the use of on-hole The air to prevent pollution on-hole ink table.
2) nail bed production: CNC drilling, drilling aperture size of 3.20 MM, the distance between holes and the hole for 5 CM, nail bed surrounded by 1. 4-1.6MM of the copper nails and nail beds common support board, The force of their uniform.
(C) silk screen board
Silk screen is the board Solder Mask Cypriot hole at the same time and completed the course, in board to customer requirements, it is necessary to ensure on-the-Cypriot-quality, silk screen on a high technical requirements: l) scraper, Selection of 60-65 degrees (Xiaoshi hardness) of scraping gum, the hardness is too high, the board will be red lines; hardness is too low, the effect of bad-Cypriots, so the choice of using the scraper, a knife review Mexico's 60 degrees Scraping gum. 2) scraping Indian pressure, the pressure should be controlled in the 6-7 KG/CM2, scraping knives and India is mainly Cypriot hole, the Mexican knife review compared to the pressure of some big, is conducive to Cypriot hole. 3) Blade speed, scraper should control the speed of 2.5 grid, scraping knives and India to slow the pace to review the Mexican knife 3-5 in the speed control grid, the best in four grid, to ensure that lines the corner of the film Solder Mask Thickness. In the silk screen process, India 5 per plate to be printed a newsprint, stick to the same version of the ink. Nail bed with a silk screen, can shorten the process, improve equipment utilization. Attention should be paid in the use of the river bed scuffing and nail indentation.
(D) curing
Volatile solvent ink is cured, molecular and narrow the gap between the resin contraction of a process, curing the use of thermal cycling bellows. In order to prevent the ink爆出hole, to take Fensan Duan curing, a relatively long time for some low-temperature, high temperature of 150 with 5 ℃, to bake 60-70 min. In a pre-curing UV machine, can effectively prevent oil bomb to the surface-polymerization more thoroughly.
With the progress of society, the ever-changing technology, PCB lines more detailed, more and more small aperture, the hole Cypriot-on-demand increasingly high, such as: Solder Mask Cypriot-hole is only 1 / 3 of around ; Two-sided and Solder Mask, not translucent-Cypriot demands: a PCB in different aperture-on-demand Cypriot hole. In short, on-Cypriot-hole Solder Mask is a crisis, suffering from various factors and the impact of the constraints to ensure that Cypriot-quality, and strictly control the process and its parameters, the whole process while ensuring the good functioning state, constantly monitoring the production Changes in a timely adjustments to ensure the quality of Cypriot hole, to further improve. Different plants have different production conditions and equipment, so there are different hole of the Cypriots, the Cypriot-appropriate selection process, to achieve customer requirements, can the fierce competition in the market in an invincible position.