IPC-7527

Requirements for Solder

Paste Printing

Developed by the Solder Paste Printing Task Group Nordic (5-21JND)

of the Component Mounting Subcommittee (5-21) of the Assembly and
Joining Committee (5-20) of IPC

Users of this publication are encouraged to participate in the

development of future revisions.

Contact:

IPC
3000 Lakeside Drive, Suite 309S
Bannockburn, Illinois
60015-1249
Tel 847 615.7100
Fax 847 615.7105
IPC-7527 May 2012

Table of Contents
1 GENERAL ................................................................... 1 Figure 5-6 Centered Deposit .............................................. 5
1.1 Scope .................................................................... 1 Figure 5-7 Centered Deposit .............................................. 5
1.2 Purpose ................................................................. 1 Figure 5-8 Offset – Acceptable .......................................... 5
1.3 Background .......................................................... 1 Figure 5-9 Offset – Acceptable .......................................... 5

1.4 Terms and Definitions ......................................... 1 Figure 5-10 Offset – Acceptable .......................................... 5
Figure 5-11 Offset – Acceptable .......................................... 5
1.4.1 Classification ........................................................ 1
Figure 5-12 Offset – Acceptable .......................................... 6
1.4.2 Disposition* ......................................................... 1
Figure 5-13 Offset – Acceptable .......................................... 6
1.4.3 Slumping .............................................................. 1
Figure 5-14 Offset – Defect .................................................. 6
1.4.4 Combined Conditions .......................................... 1
Figure 5-15 Shorting – Defect .............................................. 6
1.4.5 Designed Volume ................................................. 1
Figure 5-16 Offset – Defect .................................................. 6
1.5 Specialized Designs ............................................. 1 Figure 5-17 Area – Target .................................................... 7
1.6 Verification of Dimensions .................................. 2 Figure 5-18 Area – Target .................................................... 7
1.7 Magnification Aids ............................................... 2 Figure 5-19 Area – Acceptable ............................................ 7
1.8 Lighting ................................................................ 2 Figure 5-20 Area – Acceptable ............................................ 7
Figure 5-21 Area – Defect ................................................... 7
2 APPLICABLE DOCUMENTS .................................... 2
Figure 5-22 Height – Target ................................................. 8
2.1 IPC ....................................................................... 2
Figure 5-23 Height – Target ................................................. 8
2.2 ASTM ................................................................... 2
Figure 5-24 Height – Process Indicator ............................... 8
3 CHOICE OF TECHNOLOGY .................................... 2 Figure 5-25 Height – Defect ................................................. 8
Figure A-1 Solder Paste Printing with Squeegee
4 MEASUREMENT OF SOLDER PASTE
Blades ............................................................... 9
DEPOSITS ................................................................. 3
Figure A-2 Solder Paste Printing with Enclosed Head
5 SHAPE OF SOLDER PASTE DEPOSIT .................. 4 System .............................................................. 9
5.1 Solder Paste Deposit – Misalignment ................. 4 Figure A-3 Plastic from Packaging ..................................... 9
5.1.1 Slump ................................................................... 4 Figure A-4 Glass Fiber from PCB .................................... 10

5.1.2 Misregistration of Solder Paste Deposits ............ 5 Figure A-5 Effect of Solder Mask ..................................... 10
Figure A-6 Effect of Silk Screen ....................................... 10
5.1.3 Solder Paste Deposit – Area ............................... 7
Figure A-7 Effect of Solder Paste ..................................... 10
5.1.4 Solder Paste Deposit – Height ............................ 8
Figure A-8 Result of Silk Screen Interference ................. 10
Appendix A Guideline for Operator Trouble- Figure A-9 Saddle Shape Deposit .................................... 10
shooting in the Solder Paste
Screen Printing Process ....................... 9 Figure A-10 Roof Top Shape Paste Deposit ...................... 10
Figure A-11 Spikes on Paste Deposit ................................ 11
Figures Figure A-12 Increased Deposit Quantity ............................ 11
Figure 3-1 Squeegee Blade ............................................... 2 Figure A-13 Decreased Quantity ........................................ 11
Figure 3-2 Enclosed Paste Print Head .............................. 3 Figure A-14 Slumping/Smearing ......................................... 11
Figure 3-3 Needle Dispense .............................................. 3 Figure A-15 Paste Residues .............................................. 12
Figure 3-4 Paste Jet Dispense .......................................... 3 Figure A-16 Long Smear .................................................... 12
Figure 4-1 Sample of an Automated Machine Readout .... 3 Figure A-17 Offset .............................................................. 12
Figure 4-2 Sample of an Automated Inspection Result ..... 3 Figure A-18 Excess Residue Along Direction of Travel ..... 12
Figure 4-3 Weighing Solder Paste ..................................... 3 Figure A-19 Residue Across Direction of Travel ................ 13
Figure 5-1 Full Shape ........................................................ 4 Figure A-20 Solder Balls .................................................... 13
Figure 5-2 Saddle Shape ................................................... 4 Figure A-21 Close Up of Solder Balls ................................ 13
Figure 5-3 Roof Top Shape ................................................ 4
Figure 5-4 Pyramid Shape ................................................. 4 Tables
Figure 5-5 Full Shape ........................................................ 4 Table 1-1 Inspection Magnification (Land Width) ................ 2

iv
May 2012 IPC-7527

Requirements for Solder Paste Printing

1 GENERAL cannot be tolerated, or the end-use environment may be

uncommonly harsh.
1.1 Scope This standard is a collection of visual quality
acceptability criteria for solder paste printing. Target Condition A condition that is close to perfect/
preferred, however, it is a desirable condition and not
1.2 Purpose The purpose of this guideline document is always achievable and may not be necessary to ensure reli-
to support the user in the visual evaluation of the solder ability of the assembly in its service environment.
paste printing process, which makes subsequent process
Acceptable Condition Indicates a condition that, while not
optimizing possible.
necessarily perfect, will maintain the integrity and reliabil-
The purpose of this guideline is not to inspect and evaluate ity of the assembly in its service environment.
the quality of the solder paste. For information on the
evaluation of solder paste, see J-STD-005, Requirements Defect Condition A condition that may be insufficient to
for Soldering Pastes and IPC-HDBK-005. ensure the form, fit, or function of the assembly in its end
use environment. Defect conditions shall be dispositioned
The purpose is not to define requirements to stencil design. by the manufacturer based on design, service, and customer
For information on stencil design, see IPC-7525, Stencil requirements. Disposition may be to rework, repair, scrap,
Design Guideline. or use as is. Repair or use as is may require customer con-
Appendix A provides different error types and suggested currence.
solutions are listed. The guideline is intended to help/ A defect for Class 1 automatically implies a defect for
improve the optimizing process for paste printing. Class 2 and 3. A defect for Class 2 implies a defect for
In the case of a discrepancy, the description or written Class 3.
criteria always takes precedence over the illustrations.
1.4.2 Disposition* The determination of how defects
1.3 Background Standards such as J-STD-001 and IPC-
should be treated. Dispositions include, but are not limited
A-610 provide tools that help to promote quality within the to, rework, use as is, scrap, or repair.
electronics industry. However, the standards do not include 1.4.3 Slumping Solder paste flows out after it is applied.
requirements of visual appearance of the paste deposit. The See more in IPC-HDBK-005.
industry has, for some time, expressed a wish for a stan-
dard to support the users in the solder paste printing pro- 1.4.4 Combined Conditions There may be situations
cess. IPC-7527 will help improve the quality in this very where a combination of maximum deviations in form,
sensitive process. placement, coverage, and height can result in lack of sol-
dering or wrong amount of solder paste. The manufacturer
1.4 Terms and Definitions Other than those terms listed is responsible for identification of such conditions.
below, the definitions of terms used in this standard are in
accordance with IPC-T-50. Terms quoted from IPC-T-50 1.4.5 Designed Volume The designed volume is equal to
are marked with *. the area of the stencil aperture times the stencil thickness
(volume = length x width x height). Volume is not a visu-
1.4.1 Classification ally inspectable condition.
CLASS 1 General Electronic Products 1.5 Specialized Designs This standard, as an industry
Includes products suitable for applications where the major consensus document, cannot address all of the possible
requirement is function of the completed assembly. components and product design combinations. Where
CLASS 2 Dedicated Service Electronic Products
uncommon or specialized technologies are used, it may be
Includes products where continued performance and necessary to develop unique acceptance criteria. However,
extended life is required, and for which uninterrupted ser- where similar characteristics exist, this document may pro-
vice is desired, but not critical. Typically the end-use envi- vide guidance for product acceptance criteria. Often,
ronment would not cause failures. unique definition is necessary to consider the specialized
characteristics while considering product performance cri-
CLASS 3 High Performance Electronic Products teria. The development should include customer involve-
Includes products where continued high performance or ment or consent. For Class 3, the criteria shall include
performance-on-demand is critical, equipment downtime agreed definition of product acceptance.