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PCB MATRIX

Flexible PCBs (Flex PCBs)

Flexible printed circuit boards (FPCs) are highly reliable and extremely flexible printed circuit boards made with polyimide or polyester film as the substrate. They are characterized by high wiring density, light weight, thinness, and good bending properties. FPCs are the only solution to meet the miniaturization and mobility requirements of electronic products. They can be freely bent, rolled, and folded, withstand millions of dynamic bends without damaging the wires, and can be arbitrarily arranged according to spatial layout requirements, moving and stretching freely in three-dimensional space, thus achieving integration of component assembly and wire connection. FPCs can significantly reduce the size and weight of electronic products, meeting the needs of electronic products developing towards high density, miniaturization, and high reliability. Therefore, FPCs are widely used in aerospace, military, mobile communications, laptops, computer peripherals, PDAs, digital cameras, and other fields.

Flex – 2L: materials: Shengyi SF-202 & SF305C;  board thickness: 0.3+/-0.05mm; surface treatement:ENIG; Stiffener: PI+FR4

Flex – 2L: materials: DuPont FR8520R; board thickness: 0.2+/-0.05mm; surface treatment: ENIG

Flexible printed circuit boards (FPCs) are primarily classified by structure based on the number of conductive layers and the bonding method between the substrate and copper foil.

Classification by Number of Conductive Layers: FPCs can be divided into single-layer boards, double-layer boards, and multi-layer boards. Single-layer boards have only one conductor, a simple structure, and are suitable for low-cost, simple circuits; double-layer boards have two conductors, increasing wiring density and are suitable for medium-complexity circuits; multi-layer boards achieve multiple conductors through lamination technology and are often used in high-density, high-performance applications, such as power and ground layer designs.

Classification by Bonding Method Between Substrate and Copper Foil: FPCs are divided into adhesive-bonded flexible boards and adhesive-free flexible boards. Adhesive-bonded PCBs use adhesive to bond copper foil to a substrate (such as polyimide), resulting in lower cost but slightly less flexibility. Adhesive-free PCBs, on the other hand, are bonded directly through a thermoforming process, offering better flexibility, bonding strength, and pad flatness, making them suitable for high-reliability requirements such as COF packaging.

The demand for flexible PCBs is increasing in all business segments with especially strong demands from medical, defense and industrial markets. UMEC collaborates with several certified factories that meet our technical and order volume requirements (high mix, low batch) to meet the diverse production needs of our customers.

If you need further information or assistance, please contact us and we will be happy to help.

Our technical capability for flex PCBs

The table below shows some of our basic process capability parameters. If you don’t find the information you need in the table, please contact us and we will be happy to help you solve your problem. In addition, other pages also have information about board materials and other types of circuit boards, which can help you make design or production decisions.

Flex PCB Manufacture Capabilites
No. Item Standard Advanced Comment
1 Materials FCCL Adhesive/Adhesiveless FCCL, PET Adhesive/Adhesiveless FCCL, PET
2 Stiffener PI, FR4, Steel, Al-Based Stiffener PI, FR4, Steel, Al-Based Stiffener
3 Adhesive sheet Epoxy adhesive series, Acrylic adhesive series Epoxy adhesive series, Acrylic adhesive series
4 Coverlay Epoxy adhesive series, Acrylic adhesive series Epoxy adhesive series, Acrylic adhesive series Mainly Acrylic adhesive series
5 Basic parameters Layers 1‐4L 5-10L
6 Max. board size 300*500mm 500*2000mm
7 Min. board size 5*10mm(without birdge); 10mm*10mm(with bridge) 4*8mm(without birdge); 8mm*8mm(with bridge)
8 Board thickness(without stiffener) 0.05‐0.5mm 0.5‐0.8mm
9 Tolerance of single layer ±0.05mm ±0.03mm without stiffener
10 Tolerance of double‐layer(≤0.3mm) ±0.05mm ±0.03mm without stiffener
11 Tolerance of multi‐layer(＜0.3mm) ±0.05mm ±0.03mm without stiffener
12 Tolerance of multi‐layer(0.3mm‐0.8mm) ±0.10mm ±10% without stiffener
13 Tolerance of board thickness(including PI stiffener) ±0.05mm ±10%
14 Tolerance of board thickness(including FR4 stiffener) ±0.10mm ±10%
15 Drilling Min.Drilling hole(mech) 0.15mm 0.1mm
16 Min.Drilling hole(laser) 0.075mm 0.05mm
17 Finish hole tolerance(PTH) ±0.075mm ±0.075mm
18 Finish hole tolerance(NPTH) ±0.05mm ±0.05mm
19 Min.Distance between via and conductors 6mil (<4 layer) 5mil (<4 layer)
20 8mil (4~6 layer ) 7mil (4~6 layer )
21 12mil (7‐8 layer ) 10mil (7‐8 layer )
22 Aspect ratio(mech drill) 15:1 18:1
23 Aspect ratio(laser drill) 1.2:1 1.2:1
24 Inner layer Min. line width/spacing  (12/18um copper) 3.0/3.2mil(loop lines 6.0/6.2mil ) 2.8/2.7mil(loop lines 5/5.2mil)
25 Min. line width/spacing  (35um copper) 4.0/4.0mil(loop lines 8.0/8.0mil) 3.5/3.5mil(loop lines 7/7mil)
26 Min. line width/spacing  (70um copper) 6/6.5mil(loop lines 10/10.5mil) 5/6mil(loop lines 9/9.5mil)
27 Max.Copper thickness 2oz 3oz
28 Min.Copper thickness 1/3oz 1/3oz
29 Outer layer Min. line width/spacing  (18um copper) 3/3.2mil(loop lines 6/6mil) 2.8/2.7mil(loop lines 5.5/5.5mil)
30 Min. line width/spacing  (35um copper) 4/4.5mil(loop lines 8/8.5mil) 3.5/3.5mil(loop lines 7.5/7.5mil)
31 Min. line width/spacing  (70um copper) 6/7mil(loop lines 10/11mil) 5.5/8.5mil(loop lines 9.5/10.0mil)
32 Min. line width/spacing (105um copper) 10/13mil(loop lines 12/15mil) 9.5/12.5mil(loop lines 11.5/14.5mil)
33 Max.Copper thickness 3oz 5oz
34 Min.Copper thickness 1/3oz 1/3oz
35 Finish Line tolerance ±1.5mil ±1mil
36 Testing method Electrical testing Flying needle test, needle bed test Flying needle test, needle bed test
37 Surface treatment Surface treatment HASL, ENIG, ENEPIG, Electrolytic Nickel Gold, Soft gold, Hard gold, Immersion silver and OSP Immersion tin
38 Mixed surface treatment ENIG+OSP,ENIG+G/F ENIG+OSP,ENIG+G/F
39 Routing Routing Tolerance(Laser) ±0.05mm ±0.05mm
40 Routing Tolerance(CNC) ±0.15mm ±0.1mm
41 Others Controlled Impedance ±10% ±5%