1. Anti-corrosion ink.
1.A review of history.
Inks for corrosion-resistant masking for circuit boards came out around the middle of the last century, and the previous masking was made by adding colloids with dichromate as a photosensitive agent, during which three stages were passed:
1) Shellac as a colloidal mask: This technique was originally learned from the former Soviet Union. It is dissolved and developed with ethanol, but it is not safe to be phased out due to cumbersome operation.
2) Bone glue as a colloidal mask: this technology is transplanted from the manufacture of printing plates and signs, panels, is not resistant to storage, because of the need for high temperature solid film, and the substrate at that time is not resistant to high temperature, after repeated research and experiments, the method of combining physical solid film and chemical solid film was invented, only heating to 100 130 can be, the composition of its bone glue (with a small amount of protein tablets or without adding) is mainly made of protein colloid. It is not easy to store at a slightly higher temperature, and it was originally proposed to add preservatives, but after adding it, it will affect the performance. It was later replaced by polyvinyl alcohol colloid.
3) Polyvinyl alcohol colloidal mask: This colloidal mask overcomes the disadvantages of cumbersome operation and short storage period, and the prepared glue can be used for up to 30 40 days, so the vitality of this photosensitive adhesive is particularly strong, and it will slowly disappear until the appearance of dry film resist.
2.The earliest resist inks.
As early as the 70s of the last century, with the rapid increase in the output of televisions, tape recorders, semiconductors, and radios, the use of photosensitive adhesive to make graphics can no longer meet the urgent needs of production. The only way out – screen printing. At that time, silk screen was used to make screens, but the printing material (resist ink) was nowhere to be purchased. At this time, experts in the industry made their own dry resist inks and dry resist inks, which overcame this major technical problem at that time and accelerated the production of printed boards.
1) Homemade resist ink.
Formula 1: petroleum asphalt, talc, dry oil, solvent gasoline, etc., self-adjusting viscosity.
Recipe 2: Thick Qi, talcum powder, pigment, rosin, turpentine.
The advent of self-made resist ink, to solve the contradiction that the batch of circuit boards at that time is constantly rising, but when preparing are substitute equipment and materials, although each village has a high trick in each village, but the consistency is poor, sometimes with the change of the weather ink also suffers from "cold", the most prominent problem is that the fineness is not enough, so it is more and more prominent to affect the smoothness and accuracy of the line.
2) Commercialization of resist inks:
When the ink merchants see this business opportunity, according to the use of the process quickly produced drying and self-drying type of resist ink, with the increase in demand, in the increase in output at the same time and the introduction of alkali soluble (alkaline deink) resist ink, in the environmental protection of another step, greatly convenient for users.
3) UV curing and resist ink: with the introduction of the TV production line and its supporting single-sided production line is also constantly introduced, but also the introduction of single-sided printing graphics of UV curing ink, looking at China's market, foreign and some regions of the UV brand has landed, and the first expensive, soon the domestic national brand on the market, the end of the imported brand domination of the world, and the decline to benefit many small and medium-sized enterprises. At the same time, the supporting UV curing equipment has also been put on the market.
3.Graphic plating technology and inks.
In the early eighties, graphic electroplating technology (that is, the usual reverse plating method, which is still in application) was introduced to China. At the beginning, all the dry film resist was used as an anti-plating mask, although it was very high, but the price of the circuit board was higher, so the manufacturers were acceptable, with the decline of the circuit board, according to the product situation, some manufacturers began to choose direct screen printing graphic anti-electroplating ink, in order to maintain normal profits.
4.Anti-plating inks.
Generally, thermosetting can meet the process conditions of anti-secondary copper plating and lead tin plating, and only one-half or one-third of the dry film is calculated, but the factory needs to have excellent screen making technology and screen printing technology, and the lack of smoothness and steepness of the edge of the line is far from catching up with the dry film, strictly speaking, only 0Lines above 6mm are powerless for some boards with fine density. Therefore, many manufacturing plants apply both processes at the same time, depending on the different wire thickness and density. This kind of ink was imported at the earliest, and now domestic and imported products are sold in the market at the same time, and the difference in quality is small.
5.As early as the mid-eighties of the last century, a PCB factory in the south began to introduce a Japanese brand of optical imaging anti-electroplating ink (hereinafter referred to as wet film). First of all, it pioneered the use of wet film to make graphic masks (at that time, most of them used dry film), and with the passage of time, everyone began to understand wet film, and the application range continued to expand after a few years. To this end, the plant also held a workshop on the application of wet film to make it gradually promoted.
1) Application and promotion of wet film: Wet film is favored by users for its excellent decomposition rate, good electroplating resistance, etching resistance (alkaline etching resistance under certain conditions) and good processability. Although the debate over the use of dry film and wet film continues, it has become a recognized fact that the wide range of wet film applications and the rapid expansion speed, especially in the manufacturing plant of multi-layer boards, the graphic etching of the inner layer has already begun to be replaced by wet film, and it has developed rapidly, this is because: First, it is only 1 2 or 2 3 of the dry film from the analysis of the first day, and there is almost zero waste emission (and the dry film needs to be treated to remove the polyester film). Second, the use of wet film does not need to add special equipment (all companies that have the ability to manufacture double-sided panels have the conditions to use wet film). Third, because the wet film can resist alkaline etching under certain conditions, the manufacturer only has an alkaline etching machine, which can not only complete the pattern etching of the inner layer of the multi-layer board but also complete the pattern etching of the outer layer with PBSN or SN layer as the mask.
So far, the application of wet film is extremely common in small and medium-sized enterprises, and all small and medium-sized enterprises that use the graphic electroplating process basically use wet film to make graphics.
2) Development of wet film.
The rapid development of PCB in China has attracted the attention of PCB material manufacturers in foreign and relevant regions, especially in Taiwan and Hong Kong, and the internal relocation of PCB manufacturing plants has made the PCB business continue to develop, and it has also activated the manufacturing and application of wet film. Looking at China's PCB market, wet film brands in Japan, South Korea, Germany, the United States, France, the United Kingdom, Italy, Switzerland and other countries have also landed in the Pearl River Delta and the Yangtze River Delta, forming a competitive situation for imported brands of wet film in China's market. It ended the era of monopoly of one or two foreign wet film brands. Among the above-mentioned imported wet film brands, Japan has the most, and other countries have only.
One or two brands. With the relocation of PCB factories in Taiwan and Hong Kong, related supporting materials have also entered, of which the wet film is the most one, and the increase of the brand is like the form of molecular fission of the manufacturing, operation and sales of the wet film has formed a large market.