As its first use in very reliable military equipment in 1980s, flex-rigid PCBs possess been traditionally used in high end fields. Up to now flex-rigid panels have become one of the analysis hotspots in the PCB industry. Combining the helping function contributed by rigid boards and the features of high density and overall flexibility contributed by flex planks, flex-rigid boards are in a position of completing the 3 DIMENSIONAL assembly under different assemblage conditions, meeting the requirements regarding lightness, thinness and small size of electronic goods. Therefore, flex-rigid boards enjoy a wide application field.
Most flex-rigid boards have smothered and blind via. Think about the kind of PCBs, there usually are lots of opportunities that you can pick up flex-rigid planks with buried/blind via, therefore it is necessary to know concerning them before quoting.
Advantages and Great things about Flex-Rigid Boards
Nowadays, flex-rigid PCBs are widely used in portables, medical and military apps. Among all types regarding PCBs, flex-rigid PCBs have got the strongest resistance in opposition to extreme application environment, dependent on which their application fields will become wider. Due to the flexible feature, room size and system weight can be minimized by simply applying 3D.
In words of the flex-rigid board design, it has already been main trends that blind/buried via and High Density Interconnect (HDI) is required upon flex-rigid boards. Because associated with the large number of types associated with flex-rigid PCBs, the following content material will be displayed together with 6-layer asymmetrical flex-rigid panel as an example.
Delicate Material Preparing
The very first layer of 6-layer irregular in shape flex-rigid board is contract board while the relax five layers of this are rigid boards. Range width spacing is zero. 1mm and there usually are lots of blind/buried vias in rigid and flex-rigid area.
Because of typically the easy occurrence of delamination of flex-rigid boards, polymer-bonded acid adhesive should be picked up as pre-preg of flex-rigid associative part in order to meet the viscidity requirement. Regarding rigid layers, no circulation bonding pre-preg is chosen up.
Blind/Buried Via Technique
• Lamination method
You can find two types of laminierung methods: one-step lamination and step-by-step lamination. One-step laminierung appertains to the process of laminating all the inner tiers for one time. Short PCB manufacturing time and affordable is an benefit of this method. Yet , is actually difficult to position typically the cover player in the process of lamination and lamination defect, delamination in addition to inner layer deformation can't be found until PCB etching. On the in contrast, step-by-step lamination refers to be able to the respective flex level lamination and rigid layer lamination in which that reduces the difficulty of positioning cover layer plus graph offset in inner layer and lamination defect could be learned in period, making the most of typically the characteristics of rigid in addition to flex board material. Yet , compared with the one-step lamination, step-by-step lamination demands more operating procedures, period consumption and assistant substance with cost increased.
For flex-rigid boards with blind/buried via, step by step lamination is advised to be used in purchase to ensure the quality of blind via in addition to high alignment accuracy. Interior layer lamination goes very first and then does typically the inner-outer layer lamination. Silicone rubber as lamination substance and PET release film as mold cleaner are widely-used in both in the laminations.
• Drill approach
NC drilling and laser drilling are required for 2 times respectively on this sort of 6-layer asymmetrical flex-rigid panel and UV drilling is employed on blind via drilling. Since UV drilling will be an modern technology with relatively complicated operation, an additional reasonable cost is normally necessary by PCB houses.
• PLASMA cleaning
Plasma washing can be used to get rid of the particular dirt on via surfaces of flex-rigid boards. Flat screen cleaning follows the process of which plasmas with high lively state generate gas-solid reaction together with acrylic acid, polyimide, epoxy and a glass fiber. Then the generated gas and plasmas with out being reacted is going to be eradicated by air pumps. This specific is a complicated physical-chemical reaction. In a word, there's something you should know concerning buried/blind via in HDI flex-rigid PCBs before citing because all these everything is closely attached with your current cost, time consumption in addition to product performance.
Verify of which the unsoldered pads will not pose problems. Severe surroundings can affect these kinds of parts to cause problems. When this is a challenge, you should apply a new conformal coat towards the panel.