Download Acceptability of Printed Circuit Board Assemblies

Section 12I Manufacturing Process Specifications
Section No.: 12I.2.3, Sheet 1 of 9
Issue Date: Nov 01, 2011
Prepared By: Dan Geitner
Rev Level: 16
Additional Distribution: PCB Assembly Subcontractors
Acceptability of Printed Circuit Board Assemblies
1.0
Purpose
1.1
2.0
The purpose of this standard is to provide a compilation of visual quality acceptability
requirements for electronic assemblies manufactured by or for Magnetek. This standard is
intended to be used by Engineering, Purchasing, Manufacturing, and Inspection in the
process of designing, assembling, inspecting, or otherwise evaluating electronic
assemblies.
Scope
2.1
This standard establishes acceptability criteria for the mounting and interconnection of
electronic and mechanical components on rigid single sided, double sided, or multilayer
printed circuit boards (PCBs) where through-hole and/or Surface Mount Technology
(SMT) components are utilized. Acceptability criteria for flexible electronic circuitry, Chip
on Board (COB), Tape Assisted Bonding (TAB), or other advanced assembly techniques
are not included in this standard. In general, the acceptability criteria for Magnetek will
conform to established industry standards as presented in:
2.1.1
2.2
3.0
IPC-A-610; Acceptability of Electronic Assemblies.
Unless specified otherwise, the criteria defined in this standard will correspond to IPC
Class 2: Dedicated Service Electronic Products.
Support Documentation
3.1
Decisions regarding acceptability must be based on applicable documentation such as
contractual agreements, assembly or component drawings, customer or engineering
specifications, and referenced documents or other standards. In the event of conflict, the
following order of preference shall apply:
3.1.1
3.1.2
3.1.3
3.1.4
3.1.5
3.1.6
3.2
The purchase order, work order, or other statement of customer specification.
The assembly drawings, Bill-of-Materials (BOMs), or other engineering
specifications.
Visual inspection work instructions and/or test specifications (i.e. 96S procedures).
This standard.
The latest revision of IPC-A-610.
Standard industry practice or other applicable documents.
This standard, and other support documentation, will reside with and be maintained by the
Process Improvement Manager.
Section 12I Manufacturing Process Specifications
Section No.: 12I.2.3, Sheet 2 of 9
Issue Date: Nov 01, 2011
Prepared By: Dan Geitner
4.0
Acceptable Handling Procedures
4.1
5.0
Rev Level: 16
The general specification for handling electronic assemblies is given in Section 3.0 of IPCA-610. This specification includes basic concepts for physical handling of PCBs either
with or without attached components. An electronic assembly will not be acceptable if
physical damage in the form of cracked, chipped, or broken components and connectors,
bent or broken terminals, or badly scratched/damaged board surfaces, traces, or pads are
evident (Reference Sections 9 and 10.) Visual inspection will include evaluation of
appearance criteria such as the presence of fingerprints, soldering residues, lead trimmings,
or other contamination. It is required that workstations and packaging materials will
provide the necessary protection against Electrical Overstress (EOS) and Electrostatic
Discharge (ESD) damage.
Mechanical Assembly
5.1
This portion of the standard considers the mounting of electronic devices on a PCB, or
other components by means of, but not limited to: screws, bolts, nuts, washers, fasteners,
clips, component studs, adhesives, tie wraps, rivets, stand-offs, heat sinks, RF shields, and
connector pins. Acceptability criteria for mechanical assembly focus on proper securing
(tightness), as well as checking for physical damage to the devices, hardware, or the
mounting surface that may have occurred during the assembly process.
Screws used on printed circuit board assemblies to secure hardware to the circuit board
assembly must be secured to the torque values in the following table unless otherwise
noted on drawings or other Magnetek specifications.
Installation Torque
Into nylon lock
nut, or with use
of any thread
locking
compound
With lock washer
Into plastic (plastite type screws)
M2.5 x 0.4
5 in-lbs.
7 in-lbs
3 in-lbs.
#4-40
5 in-lbs.
8 in-lbs
4 in-lbs.
#6-32
10 in-lbs
12 in-lbs
6 in-lbs.
Thread
size
Section 12I Manufacturing Process Specifications
Section No.: 12I.2.3, Sheet 3 of 9
Issue Date: Nov 01, 2011
Prepared By: Dan Geitner
Rev Level: 16
Note: Compliance to torque requirements shall be verified as specified in assembly
drawings or other Magnetek specifications. If torque verification is performed, the
procedure shall ensure that no damage to the components or the assembly occurs.
In general, the mechanical assembly portion of this standard conforms to Section 4.0 of
IPC-A-610 and includes discussion of:
5.1.1
5.1.2
5.1.3
5.1.4
5.1.5
5.1.6
5.1.7
5.1.8
5.2
6.0
Hardware.
Eyelets.
Mechanical Component Mounting.
Connectors, Handles, and Extractor Mounting.
Heatsink Mounting and Bonding.
Terminals.
Connector Pin Installation.
Wire Securing and Routing
In addition, the following special acceptability criteria shall apply as necessary.
5.2.1
All metal tabs, spring leads, etc., on snap-in parts which are intended for electrical
connections to the conductive pattern on a PCB, shall be in contact with the
conductive pattern to which they are to be soldered.
5.2.2
When screws and nuts are required to mount a bracket or component, the screw
head should be on the bottom side of the PCB with a star washer, unless otherwise
specified.
5.2.3
Parts that extend more than 1/8 inch above the bottom (solder) side of a PCB must
be mounted after wave soldering.
5.2.4
Assemblies using the 05P00036-0287 and 05P00036-0285 relay with the
05P00034-0228 socket must have the retaining spring (01P00001-0146) properly
attached to each such relay/socket combination.
5.2.5
Assemblies using a PCB terminal strip (05P00060-0211 typical) must have a
properly installed keying plug (05P00060-0212).
5.2.6
All re-drilled or additional holes used for component installation in double sided
PCBs must have properly mounted eyelets.
Component Installation, Location, and Orientation
Section 12I Manufacturing Process Specifications
Section No.: 12I.2.3, Sheet 4 of 9
Issue Date: Nov 01, 2011
Prepared By: Dan Geitner
Rev Level: 16
6.1
This portion of the standard discusses acceptability requirements for the installation,
location, and orientation of components and wires as described in Sections 6.0 through 8.0
of IPC-A-610. The criteria in this section refer to direct mounting of components to PCB
lands or pads as well as indirect mounting to terminals or connector pins. Where
applicable, adhesive bonding as described in IPC-A610, sections 7.3.2 and 7.3.3.
6.2
In addition, the following special acceptability criteria shall apply as necessary.
6.2.1
On double sided and multi layer boards, all capacitors with a diameter (or major
dimension) larger than 3/4 inch or longer than 1-3/4 inches shall be bonded to the
PCB with RTV as specified on the Bill of Material. On single sided boards all
capacitors 1 inch or longer will be bonded to the PCB with RTV. Additional
support may be provided by means of tie-wraps as specified on the assembly
drawing.
6.2.2
When mounting 3 Watt or greater resistors with axial leads, the resistor body must
have a 1/8” to 1/4” clearance off the board. Leads are to be bent to form a standard
stress relief on both sides of the component.
6.2.3
When mounting 5 Watt or greater resistors, the components shall be bonded to the
PCB with RTV as specified on the Bill of Material. The RTV shall contact the
resistor for the first 1/4” on each end of the resistor.
6.2.4
Coated or sealed components that are to be vertically mounted shall have a
maximum of 0.200 in. from the top of the mounting hole to the end of the meniscus
on the lead.
6.2.5
Special mounting procedures for transistors with TO-105 or TO-92 packages may
be required in the case of older PCB layouts. Transistors with part numbers 5P300020, 0023, 0033, 0034, and 0053 may be supplied in either the TO-105 or TO-92
package. With the TO-105 package the transistor leads should be straight and
mounted as shown on the PCB silk-screen or assembly drawing. For transistors
with the TO-92 package, the leads will be bent and inserted into the plated through
holes as shown in the Figure given below. Note that the line markings on the silkscreen denoting the flat on the case will not correspond with the flat on the TO-92
package.
Section 12I Manufacturing Process Specifications
Section No.: 12I.2.3, Sheet 5 of 9
Issue Date: Nov 01, 2011
Prepared By: Dan Geitner
OLD ( TO-105 )
6.2.6
7.0
In those cases where a component lead or a bare conductor may come in contact
with a trace, pad, or an un-insulated part of a component, the wire or lead in
question shall be covered with an insulating plastic sleeve. The sleeving shall be
specified in the assembly drawing or, preferably, in the BOM.
This portion of the standard considers the acceptability requirements for soldered joints of
all types except those usually associated with Surface Mount devices. The soldering of
SMT components is reviewed in Section 14 of this standard. The discussion of soldering
in this standard is based on Sections 6.0 and 7.0 of IPC-A-610.
Cleanliness
8.1
9.0
NEW ( TO-92 )
Soldering
7.1
8.0
Rev Level: 16
The acceptability requirements for circuit assembly cleanliness are outlined in Section
10.4 of IPC-A-610. Additionally the following is required:
8.1.1
Magnetek requires the use of “no clean” solder flux for the purposes of wave and
SMT soldering, and “no clean” flux in solder cores for manual component
connection, rework, and solder joint touchup. Circuit board assemblies, which
have been wave soldered, are not cleaned because the flux residue is not usually
visible and is not chemically active. The residue from hand soldering is often
visible but is not removed unless specified in appropriate process documentation.
8.1.2
If aqueous flux is used, a cleanliness level of a maximum of 1.56 Micrograms/cm2
sodium chloride (NaCl) equivalent ionic or ionizable flux residue is specified.
Cleanliness to be verified via solvent extract methods as specified in IPC-TM-650.
Production Lot Testing
Section 12I Manufacturing Process Specifications
Section No.: 12I.2.3, Sheet 6 of 9
Issue Date: Nov 01, 2011
Prepared By: Dan Geitner
10.0
Rev Level: 16
9.1
All printed circuit board assemblies to be 100% electrically tested, unless specified or
deviated otherwise. Test methodology, test coverage, and test electrical requirements to be
mutually agreed upon between Magnetek and PCB supplier.
9.2
Upon successful completion of electrical test, assemblies to be marked with a “Test” stamp
in accordance with Sec. 10.
Marking
10.1
The general specifications for the acceptability of various markings are presented in
Section 10.3 of IPC-A-610. Marking provides product and process identification, status,
and traceability. At Magnetek, markings and labels have various formats and are utilized
for many different purposes. Examples of markings addressed by this standard include,
but are not limited to, the following:
10.1.1
10.1.2
10.1.3
10.1.4
10.1.5
10.1.6
10.2
Magnetek and supplier logos on PCBs.
Assembly and PCB part numbers, date codes, and revision levels.
Component legends including reference designators and polarity indicators.
Inspection and test traceability labels.
Relevant regulatory agency (UL, etc.) logos and certifications.
Installation and user information.
The specification of a marking style and orientation, label material and size, and print
formats shall be defined in appropriate BOMs and assembly drawings.
10.2.1 If a marking consists of a stamped number, it shall be applied to the PCB surface
with a non-conductive, permanent ink (not soluble in water or alcohol,) and coated
with clear varnish.
10.2.2 Unless otherwise specified, all labels will be clean white adhesive backed paper.
10.3
Unless specified otherwise, a marking shall not cover or disfigure another marking. For
example, a test label or stamp shall not cover a PCB date code or part number.
10.4
The following PCB marking/labeling criteria are utilized:
10.4.1 The sub-assembly BOM number shall be permanently affixed to the component
side of the PCB. Some boards, which have a BOM number stamped or silkscreened onto the laminate surface, may be used for more than one assembly. It is
required that the proper 46S BOM numbers appear on the PCB if the assembly
BOM number is different from the permanent marking.
10.4.2 The PCB supplier shall provide a label on the PCB that indicates the latest change
or revision number in an area adjacent to the BOM number. The change (revision)
Section 12I Manufacturing Process Specifications
Section No.: 12I.2.3, Sheet 7 of 9
Issue Date: Nov 01, 2011
Prepared By: Dan Geitner
Rev Level: 16
number label shall be placed so as not to interfere with or be considered as part of
the BOM number.
Note: Items 10.4.1 and 10.4.2 may be combined on a single label.
10.4.3 The manufacturer shall provide labels indicating that ATE, functional test, or visual
inspection has been performed.
Each manufactured PCB assembly shall have a unique serial number. Serial
number labels shall specify the date code, production source, and serial number, in
both a Code 3 of 9 bar code and human readable format. This data will appear in a
coded format consisting of a seven (7) digit number structured as follows:
10.4.4.1
First Digit - Year:
1990
1991
1992
1993
1994
10.4.4.2
E
F
G
H
J
K
L
M
N
P
2000
2001
2002
2003
2004
Q
R
S
T
U
2005
2006
2007
2008
2009
V
W
X
Y
Z
2010
2011
2012
2013
2014
A
B
C
D
E
Second Digit - Month:
Jan
Feb
Mar
Apr
10.4.4.3
1995
1996
1997
1998
1999
A
B
C
D
May
Jun
Jul
Aug
E
F
G
H
Sept
Oct
Nov
Dec
J
K
L
M
Third Digit - Manufacturing Code:
The manufacturing code will consist of a singular alpha character.
For confidentiality, the table containing the manufacturing codes is
maintained in a separate document, document # MPS12I.2.3.A. The
specific manufacturing code will be furnished to respective suppliers
on the purchase order, in the “Vendor Special Instructions” area.
This code will be furnished by the Process Engineering group and
maintained in document MPS12I.2.3.A. The code shall be entered
into the Magnetek vendor database by purchasing.
Section 12I Manufacturing Process Specifications
Section No.: 12I.2.3, Sheet 8 of 9
Issue Date: Nov 01, 2011
Prepared By: Dan Geitner
10.4.4.4
Rev Level: 16
Fourth Through Seventh Digits:
The last four digits of the serial number code shall be numerals
beginning with 0000. Note: These digits restart at 0000 on the 1st
of each month.
10.4.4.5
All date code data for years prior to 1990 will reside with and be
maintained by the Process Engineering Manager.
Serial Number 0001
Made in Menomonee Falls
Made in Month of November
Made in 2006
10.4.5 All field returns require an additional date code label. A three-character date code,
as defined in 10.4.4.1, 10.4.4.2 and 10.4.4.3, shall be applied as close as possible to
the original serial number by the responsible party conducting the repair. This
shall indicate that the PCB or assembly has been properly ECO updated and has
passed all required electrical tests.
11.0
Coatings
11.1
12.0
This portion of the standard considers the visual acceptability requirements for solder mask
on PCBs and conformal coating of assembled boards as summarized in Section 10.5 of
IPC-A-610.
Laminate and Component Condition
12.1
This portion of the standard considers the visual acceptability requirements for the
laminated PCB material as discussed in Sections 10.1, and 10.2 of ANSI/IPC-A-610.
12.2
Additional criteria, including acceptability criteria for traces, pads, lands, and through hole
plating are specified in ANSI/IPC-RB-276 and IPC-6012B, Qualification and Performance
Specification for Rigid Printed Boards.
12.3
Component condition shall be maintained at the acceptable as-received level as specified
by Magnetek, Purchasing Specifications, or supplier documentation. In the event of
conflict between these documents, the Magnetek Purchasing Specifications will take
precedence.
Section 12I Manufacturing Process Specifications
Section No.: 12I.2.3, Sheet 9 of 9
Issue Date: Nov 01, 2011
Prepared By: Dan Geitner
13.0
Discrete Wiring Assembly
13.1
14.0
Rev Level: 16
This portion of the standard provides acceptability criteria for the material, routing, surface
bonding, and connection of discrete wires as discussed in Section 11.0 of IPC-A-610.
Surface Mount Assemblies
14.1
This portion of the standard provides acceptability criteria for the placement and
interconnection of SMT components as discussed in Section 8 of IPC-A-610.