IEC 61249-8-8:1997 pdf download

IEC 61249-8-8:1997 pdf download.Materials for interconnection structures – Part 8: Sectional specification set for non-conductive films and coatings
1 Scope
This specification within the IEC 61 249 series details requirements for the qualification of temporary solder resist coatings. These have been referred to as a mask in this specification since they have the facility of being readily removed. Peelable solder masks are applied (usually by screen printing) to areas of a completed printed board or panel prior to shipment, in order to protect areas of the board or panel during subsequent processes by the board assembler. Typically, peelable solder masks are used to protect keypad contacts during fluxing and subsequent mass soldering. Removal of the mask will then leave a residue-free untinned contact area. Requirements stated in this specification will also have some limited validity for assessing the suitability of printed boards which are supplied with peelable solder masks. Requirements for the release of printed boards using peelable solder masks should be included in the Customer Detail Specification (CDS). Requirements for the qualification of permanent polymeric solder resistive coatings are given in IEC 61 249-8-5 1 ) , which has been used as a template in constructing this specification, in as far as it may apply.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this section of IEC 61 249-8. At the time of publication, the editions indicated were valid. All normative documents are subject to revision, and parties to agreements based on this section of IEC 61 249-8 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.
IEC 60068-2-20: 1 979, Basic environmental test procedures – Part 2: Tests – Test T: Soldering
Amendment No. 1 (1 987)
IEC 61 1 89-1 : 1 997, Test methods for electrical materials, interconnection structures and
assemblies – Part 1 : General test methods and methodology
IEC 61 1 89-2: 1 997, Test methods for electrical materials, interconnection structures and
assemblies – Part 2: Test methods for materials for interconnection structures
IEC 61 1 89-3: 1 997, Test methods for electrical materials, interconnection structures and
assemblies – Part 3: Test methods for interconnection structures (printed boards)
IEC 61 249-8-5: Materials for interconnection structures – Part 8: Sectional specification set for
non-conductive films and coatings – Section 5: Permanent polymer coatings 1 )
IEC 62326-4-1 : 1 996, Printed board – Part 4: Rigid multilayer printed boards with interlayer
connections – Sectional specification – Section 1 : Capability detail specification: Performance
levels A, B and C
3 Properties
3.1 General In all cases the peelable solder masks shall be stored, applied, and cured in accordance with the material supplier’s instructions. The cured coating shall produce a tough and resilient coating without voids and/or pinholes in the temporary solder mask. Unless otherwise specified, the test sample shall comprise five chequerboard test specimens, details of which are given in IEC 62326-4-1 , test specimen G. Many of the tests can be conducted in sequence on the same test specimen. The following tests are specified in IEC 61 249-8-5, but are not considered necessary for peelable solder mask due to the nature and use of the material
3.2 Adhesion (pressure sensitive tape method) When tested in accordance with IEC 61 1 89-3 Test 3X1 2, there shall be no evidence of peelable solder mask adhering to the printed board or in any holes. NOTE – This is the reverse of the requirement for permanent organic surface coatings. This test shall be conducted: a) without conditioning; b) after thermal shock with the peelable mask down in accordance with IEC 61 1 89-3, test 3N02. The float time shall be 5 s. This method is considered to be more objective than the hand peel technique, and is the referee method. 3.3 Adhesion (hand peel technique) A minimum of three complete production boards shall be used for this test. The peelable solder mask shall be readily removable by hand, and shall detach in a single piece (pattern permitting). After removal of the mask, there shall be no residue or debris on the surface of the printed board or in any holes.