Stack-up for FPC
The following is the usual FPC stackup information. If you need custom FPC stackup, please make note and we will manufacture according to your requirement.

Polyimide (PI) is the most commonly used thermal curing insulating material in flexible circuit processing. The thickness range of the material is generally 12.5μm (0.5mil) and 125μm (5mil). Divided into with glue and without glue, the DK with glue is 3.5, and the DK without glue is 3.3.
Single layer FPC stackup
| top coverlay | PI | 12.5um |
| Adhesive | 15um | |
| top copper layer | Copper | 18um(Finished Copper thickness 18um |
| Adhesive | 13um | |
| PI | 25um dielectric constant 3.3~3.5 (The DK value is not absolute and will vary depending on the base material's models and thickness.) | |
| Total thickness | 83.5um |
2 layer FPC stackup
| top coverlay | PI | 12.5um |
| Adhesive | 15um | |
| top copper layer | Copper | 18um(Finished Copper thickness 18um |
| Adhesive | 13um | |
| PI | 25um dielectric constant 3.3~3.5 (The DK value is not absolute and will vary depending on the base material's models and thickness.) | |
| Total thickness | 83.5um |
4 layer FPC stackup
| top coverlay | PI | 12.5um |
| Adhesive | 15um | |
| top copper layer | Copper | 12um(Finished Copper thickness 18um) |
| Adhesive | 0um | |
| PI | 25um dielectric constant 3.3~3.5 (The DK value is not absolute and will vary depending on the base material's models and thickness.) | |
| Pure gum | 13um | |
| copper 2 layer | Copper | 12um |
| Adhesive | 0um | |
| PI | 25um | |
| Adhesive | 0um | |
| copper 3 layer | Copper | 12um |
| Pure gum | 13um | |
| PI | 25um dielectric constant 3.3~3.5 (The DK value is not absolute and will vary depending on the base material's models and thickness.) | |
| Adhesive | 0um | |
| bottom copper layer | Copper | 12um(Finished Copper thickness 18um) |
| bottom coverlay | Adhesive | 15um |
| PI | 12.5um | |
| Total thickness | 204um |
4 layer rigid-flex FPC stackup
| Rigid part | Flex part | |||
|---|---|---|---|---|
| top soldermask layer | 20um | |||
| rigid-top copper layer | Copper | 18um(Finished Copper thickness 35um) | ||
| FR4 | 680um | PI | 12.5um | |
| Pure gum | 13um | Adhesive | 15um | |
| flex-copper 2 layer | Copper | 18um | Copper | 18um |
| Adhesive | 13um | Adhesive | 13um | |
| PI | 25um dielectric constant 3.3~3.5 (The DK value is not absolute and will vary depending on the base material's models and thickness.) | PI | 25um dielectric constant 3.3~3.5 (The DK value is not absolute and will vary depending on the base material's models and thickness.) | |
| Adhesive | 13um | Adhesive | 13um | |
| flex-copper 3 layer | Copper | 18um | Copper | 18um |
| Pure gum | 13um | Adhesive | 15um | |
| FR4 | 680um | PI | 12.5um | |
| rigid-bottom copper layer | Copper | 18um(Finished Copper thickness 35um) | ||
| bottom soldermask layer | 20um | |||
| Total thickness | 1549um | FPC thickness | 142um |
6 layer FPC stackup
| top coverlay | PI | 12.5um | ||
| Adhesive | 15um | |||
| top copper layer | Copper | 12um(Finished Copper thickness 18um) | PI | 12.5um |
| Adhesive | 0um | Adhesive | 15um | |
| PI | 25um dielectric constant 3.3~3.5 (The DK value is not absolute and will vary depending on the base material's models and thickness.) | Copper | 18um | |
| Pure gum | 13um | Adhesive | 13um | |
| copper 2 layer | Copper | 12um | PI | 25um dielectric constant 3.3~3.5 (The DK value is not absolute and will vary depending on the base material's models and thickness.) |
| Adhesive | 0um | Adhesive | 13um | |
| PI | 25um | Copper | 18um | |
| Adhesive | 0um | Adhesive | 15um | |
| copper 3 layer | Copper | 12um | PI | 12.5um |
| Pure gum | 13um | |||
| Coverlay | 27.5um | |||
| copper 4 layer | Copper | 12um | FPC thickness | 142um |
| Adhesive | 0um | |||
| PI | 25um | |||
| Adhesive | 0um | |||
| copper 5 layer | Copper | 12um | ||
| Pure gum | 13um | |||
| PI | 25um dielectric constant 3.3~3.5 (The DK value is not absolute and will vary depending on the base material's models and thickness.) | |||
| Adhesive | 0um | |||
| bottom copper layer | Copper | 12um(Finished Copper thickness 18um) | ||
| bottom coverlay | Adhesive | 15um | ||
| PI | 12.5um | |||
| Total thickness | 293.5um |
Have Questions?
If you have any questions or need any further information, please feel free to contact your dedicated customer service.
