Experience in producing halogen-free PCB

Halogen-free sheet supplier

At present, there are a large number of plate suppliers, which have developed or are developing halogen-free copper clad laminates and corresponding prepregs. We know PCL-FR-226/240 with Polyclad, DEl04TS with Isola, and S1155/S0455 for Shengyi. , South Asia, Hongren GA-HF and Matsushita Electric GX series.

In 2002, we started to use Polyclad's PCL-FR-226/240 sheet for the production of mobile phone battery panels. This year, we developed the production of Shengyi S1155 substrate and multi-layer board, and the halogen-free sheet of South Asia is also being tested. in. At present, the use of halogen-free plates has accounted for 20% of the total plate consumption of our company.

3.1 Lamination:

Lamination parameters may vary from company to plate. Take the raw substrate and PP as the multi-layer board mentioned above, in order to ensure the sufficient flow of the resin, the bonding force is good, and the lower heating rate of the sheet (1.0-1.5 ° C / min) and the multi-stage are required. Pressure matching, in the high temperature phase, requires a longer time, 180 ° C for more than 50 minutes. The following is a recommended set of platen settings and actual sheet temperature rise. The pressed plate was used to detect the bonding force between the copper foil and the substrate being 1.ON/mm, and the plate after the electric drawing showed no delamination or bubble phenomenon after six times of thermal shock.

3.2 Drilling processability:

Drilling conditions are an important parameter that directly affects the quality of the hole wall of the PCB during processing. The halogen-free copper-clad laminate uses P, N series functional groups to increase the molecular weight and enhance the rigidity of the molecular bonds, thereby enhancing the rigidity of the material. At the same time, the Tg point of the halogen-free material is generally higher than that of the ordinary copper-clad laminate, so the ordinary The drilling parameters of the FR-4 are drilled, and the effect is generally not ideal. When drilling a halogen-free board, it is necessary to make some adjustments under normal drilling conditions.

For example, our company uses the four-layer board made by Shengyi S1155/S0455 core board and PP, and the drilling parameters are not the same as the normal drilling parameters. When drilling a halogen-free board, the rotation speed is 5-10% faster than the normal parameter, and the feed and retraction speed are 10-15% lower than the normal parameters, so that the drilled hole has a small roughness.

3.3 alkali resistance

Generally, the anti-alkaline of the halogen-free sheet is worse than the ordinary FR-4. Therefore, in the etching process and on the rework process after the solder mask, special attention should be paid to the fact that the soaking time in the alkaline film-removing liquid cannot be too long. In case of white spots on the substrate. In the actual production, our company has suffered losses: the halogen-free board that has been soldered and cured has some problems to be washed back, but it is still in accordance with the normal FR-4 backwashing method at the time of returning to washing. After immersing in a concentration of 10% NaoH at 75 ° C for 40 minutes, the white spots of all the substrates washed out were shortened to 15-20 minutes, and the problem no longer existed. Therefore, it is best to do the first board for the reflow soldering of the halogen-free board to get the best parameters and then rework in batches.

3.4 Halogen free soldering production

At present, there are many kinds of halogen-free solder resist inks introduced in the world, and its performance is not much different from that of ordinary liquid photosensitive inks. The specific operation is basically the same as ordinary ink.