BS 61191-4:2017 pdf download – Printed board assemblies Part 4: Sectional specification – Requirements for terminal soldered assemblies (IEC 61191-4:2017)
1 Scope
This part of IEC 61191 prescribes requirements for terminal soldered assemblies. Therequirements pertain to those assemblies that are entirely terminal/wire interconnectingstructures or to the terminal/wire portions of those assemblies that include other relatedtechnologies (i.e. surface mounting, through-hole mounting, chip mounting).
2Normative references
The following documents are referred to in the text in such a way that some or all of theircontent constitutes requirements of this document.For dated references,only the editioncited applies.For undated references, the latest edition of the referenced document (includingany amendments) applies.
IEC 60194,Printed board design,manufacture and assembly – Terms and definitions
IEC 61191-1:2013,Printed board assemblies – Part 1: Generic specification – Requirementsfor soldered electrical and electronic assemblies using surface mount and related assemblytechnologies
3Terms and definitions
For the purposes of this document, the terms and definitions given in lEC 60194 apply.
lSo and lEC maintain terminological databases for use in standardization at the followingaddresses:
· IEC Electropedia: available at http://www.electropedia.orgl
. IsO Online browsing platform: available at http://www.iso.orglobp
4General requirements
Requirements of lEC 61191-1 are a mandatory part of this specification.
Workmanship shall meet the requirements of lPC-A-610 in accordance with the classificationrequirements of this document.
5 General terminal and part mounting requirements
5.1 General
The requirements of 5.2 are applicable to terminals and part mounting in all types ofassembiies.
5.2 Wire and cable preparation
5.2.1 General
Sufficient insulation cover shall be stripped from the wire or leads to provide for insulation clearances as specified. Chemical stripping agents shall be used for solid wire only and shall be neutralized or removed prior to soldering. In stripping insulation, care should be taken to avoid nicking or otherwise damaging the wire or the remaining insulation. For level A or B assemblies, the number of nicked or broken strands in a single wire shall not exceed the limits given in Table 1 . For wires used at a potential of 6 kV or greater, or for level C assemblies, there shall be no broken strands. The number of nicked strands shall be in accordance with Table 1 . Insulation discolouration resulting from thermal stripping is permissible.
5.2.2 Tinning of stranded wire
Portions of stranded wire to be soldered shall be tinned prior to mounting. The solder shall wet the stranded wire and penetrate to the inner strands of the wire. Wicking of solder under the insulation shall be minimized.
5.3 Terminal installation
5.3.1 General
The detailed requirements for installation of solder terminals are defined in 5.3.2 to 5.3.8.
5.3.2 Terminal mounting (mechanical)
Terminals not connected to printed wiring or ground planes shall be of the rolled flange configuration (see Figure 1 ). A printed foil land may be used as a seating surface for a rolled flange provided that the land is isolated and not connected to active printed wiring or ground plane.
5.3.3 Terminal shank discontinuities The shank of the terminal shall not be perforated, split, cracked, and there shall not be discontinuity to the extent that oils, flux, inks, or other substances used for processing the printed board can be entrapped. Circumferential cracks or splits in the shank are not acceptable regardless of the extent.
5.3.4 Flange discontinuities The rolled flange shall not be split, cracked or otherwise discontinuous to the extent that flux, oils, inks, or other liquid substances used for processing the printed board can be entrapped within the mounting hole. After rolling, the rolled area shall be free of circumferential splits or cracks, but may have a maximum of three radial splits or cracks provided that the splits or cracks are separated by at least 90° and do not extend into the barrel of the terminal (see Figure 2).
5.3.5 Terminal mounting (electrical) Flared flange terminals shall be mounted in non-interfacial plated through-holes provided the mounting is in conjunction with a land or ground plane on the flared side as shown in Figure 3a. They shall not be flared to the base material of the printed board. Funnel shoulder terminals shall not be used (see Figure 3b). Terminals may be mounted in non-plated through-holes with active circuitry on the top-side (or primary side) and a rolled flange on the backside of the board (see Figure 3c).