scope:

This standard establishes the classification system, the qualification and quality conformance requirements for flexible metal-clad dielectric materials to be used for the fabrication of flexible printed circuitry and flexible flat cable.

This specification supersedes IPC-FC-241C and the requirements herein meet or exceed the requirements for Class 3 in this superseded document. Note that conformance to Class 3 met or exceeded conformance to Classes 1 and 2. IPC-4204 no longer utilizes the 3-class system.

Classification System The system described in 1.1.1 through 1.1.2.7 identifies flexible metal-clad dielectrics.

Nonspecific Designation A nonspecific designation is intended for use by designers on master drawings to designate their material choice. Further specification details may be indicated by using the specific designation in drawing notes and purchase documents. At the end of this standard is a series of material specification sheets designated by individual nonspecific designators. Each sheet outlines engineering and performance data for a flexible metal-clad dielectric, indicating base material type, adhesive type and method of reinforcement. The sheets are provided with a number for ordering purposes. For example, if a user wishes to order from specification sheet number 1, the number "1" would be substituted for the "S" in the designation example (i.e., IPC-4204/1).

Example of nonspecific designation:

IPC-4204/S

Where S is specification sheet number

Specific Designation The specific designation shall be in the following form and is intended for use on purchase orders (see 6.1). The specific designation shall not be used by designers on master drawings to indicate their material selection. Master drawings shall indicate the material design by the nonspecific designation, supplemented in notes with the material specification details as defined by the specific designation. This procedure is necessary because the specific designation is normally lengthy and will not fit the field for most computer cataloging.

Example of specific designation:

IPC-4204/S - C1E2M3/3 CU-W7-1P/1P

Where:

IPC-4204/S - Nonspecific Designation (see 1.1.1)

C - Base Dielectric Type Designation (see 1.1.2.1)

1 - Reinforcement Method Designation (see 1.1.2.2)

E - Reinforcement Type Designation (see 1.1.2.3)

2 - Base Dielectric Thickness Designation (see 1.1.2.4)

M - Adhesive Type Designation (see 1.1.2.5)

3/3 - Adhesive Thickness Designation (see 1.1.2.6)

CU-W7-1P/1P - Metal Cladding Designation (see 1.1.2.7)

Note: The letter "X" shall be entered into the designation where an item is not specified (e.g., dielectric thickness).

Base Material Type The type of dielectric material shall be specified per Table 1-1.

Reinforcement Method The reinforcement method shall be specified per Table 1-2.

Reinforcement Type The reinforcement type shall be specified per Table 1-3.

Base Material Thickness The base material thickness is expressed by a designator (see Table 1-4).

Adhesive Type The adhesive shall be specified per Table 1-5.

Adhesive Thickness Adhesive thickness is expressed by a designator (see Table 1-4). The thickness on each side of the clads are separated by a slash.

Metal Cladding Metal cladding should be specified per IPC-4562, Metal Foil for Printed Wiring Applications. 1.1.2.7.1 through 1.1.2.7.6 represent exerpts from the current version of IPC-4562 at the time of publication of IPC-4204, except that all references to class and profile of foils are omitted. If foil profile or foil class are required, these shall be included in the procurement documentation.

Example of metal cladding designation:

CU-W7-1P/1P

Where

CU - Foil Metal Designation (see 1.1.2.7.2)

W - Foil Type Designation (see 1.1.2.7.3)

7 - Foil Grade Designation (see 1.1.2.7.4)

2 - Foil Thickness Designation (see 1.1.2.7.5)

P - Bond Enhancement Treatment Designation (see 1.1.2.7.6)

Specification Sheet Designation The specification sheet number in IPC-4562 shall be used for metal cladding. For metal foils not listed in the latest revision of IPC-4562, a 0 (zero) shall be listed as the specification sheet number (e.g., IPC-4562/0).

Metal Foil The metal foil shall be designated by a suitable two- or three-letter code:

CU Copper

NI Nickel

XX Other

Metal Foil Type Metal foil types shall be distinguished by their process of manufacture and shall be designated as:

E Electrodeposited

W Wrought (Rolled)

O Other

Foil Grades Foil grades shall be distinguished according to the foil grade designations per Table 1-6.

Nominal Metal Cladding Thickness The area weight and nominal thickness for copper shall be as identified in Table 1-7. For foils other than copper, thickness shall be indicated by dimensions to the nearest 0.025 mm [0.001 in].

Bond Enhancement Treatment The bond enhancement treatment used on the metal foil shall be designated as one of the following:

N No treatment; no stain proofing.

P No treatment; stain proofing both sides.

S Single-sided bond enhancement treatment (matte side); stain proofing on both sides.

D Double-sided bond enhancement treatment; stain proofing on both sides.

R Reverse-treated bond enhancement (cathode side); stain proofing on both sides.

Qualification The flexible metal-clad dielectric materials that meet all the requirements of this standard shall be qualified products (see 4.7).

Quality Conformance This standard establishes a quality conformance system for the manufacturers to demonstrate the continual conformance of a flexible base dielectrics material to the quality requirements of the standard. See 4.8 for quality conformance inspection requirements.

Material Characteristics The flexible materials made to this standard use established requirements to enable the material to be applied in a broad range of applications. Materials made to this standard may have characteristics that meet a specific enhanced performance need. Both the user and supplier should review these enhancements.

New Materials The flexible metal-clad dielectrics contained in this standard represent known materials. As new materials become available, they will be added to future revisions. Users and material developers are encouraged to supply information on new flexible materials using the blank specification sheet at end of this standard for review by the IPC Flexible Circuits Base Materials Sub-committee (D-13). Users who wish to invoke this standard for flexible materials not listed shall list a zero for the specification sheet number (i.e., IPC-4204/0).

New or revised specification sheets may become approved by the committee independent from revision of the standard. When this occurs, the new or revised specification sheet shall become part of the standard. Per 6.1, the specification sheet revision date shall be specified in the order.