Inspection Of Hidden Solder Connections - NASA
Inspection of Hidden Solder Connections John Denning TRW Space and Electronics Group 1
Inspection of Hidden Solder Connections Introduction “Hidden” Solder Joint Types and Resulting Inspection Challenges Traditional Inspection Methods New Inspection Methods Available Conclusion 2
Inspection of Hidden Solder Connections 3 Introduction The assembly process determines joint integrity, not inspection!!!!!! PWB solder joint miniaturization New inspection challenges Traditional inspection methods may not be sufficient for solder joint assessment What are the inspection alternatives? What is the latest and greatest available?
Inspection of Hidden Solder Connections “Hidden” Solder Joint Types and Resulting Inspection Challenges What’s a hidden solder joint? Surface mount components - All types of BGA (Micro BGA, PBGA, CBGA, CCGA) - J-leads - CSP Densely populated through hole components - Backplane connectors 4
Inspection of Hidden Solder Connections Traditional Inspection Methods (Industry Standards) Microscope inspection Pros - Partial view of solder joint parallel to PWB edges Cons - Extensive board handling increasing the possibility for damage - Results are subjective - Unable to view multiple rows of joints and unable to view between component gaps 5
Inspection of Hidden Solder Connections 6
Inspection of Hidden Solder Connections Traditional Inspection Methods (Industry Standards) Cross sectional analysis Pros - Able to view solder joint integrity, presence of cracks and microstructure condition can be determined - Ability to view multiple rows through additional sections - Z-axis or planar views possible Cons - Destructive test, not practical for process inspection - Labor intensive - Two dimensional aspect only 7
Inspection of Hidden Solder Connections Traditional Cross Section Inspection Of BGA Joints 8
Inspection of Hidden Solder Connections Traditional Cross Section Inspection Of a BGA Joint 9
Inspection of Hidden Solder Connections Traditional Inspection Methods (Industry Standards) Electrical testing Pros - 100% assembly verification - Simple, pass or fail (either it works or it doesn’t) Cons - Does not reflect certain anomalous solder joint conditions (i.e. cold joints, partial cracks, voiding, etc.) - Solder joint contamination may be over looked 10
Inspection of Hidden Solder Connections Traditional Inspection Methods (Industry Standards) X-ray inspection Pros - Provides an internal view all solder joints in a non-destructive fashion Cons - 1:1 ratio of x direction views (tilt views are possible) - Difficult to assess solder joints of a fully populated PWB, many obstructions could be present - Film interpretation labor intensive - Unable to distinguish cold joints, fine cracks, flux contamination, etc. 11
Inspection of Hidden Solder Connections 12 New Inspection Methods Available 90 prism assisted microscope inspection Pros - Easy to use and systems are relatively inexpensive at 25 to 30K - Minimizes PWB handling - Can view one full side of periphery BGA solder joints. Able to view for BGA solder joint cracks - Able to inspect between components with gaps as tight as 35 mils and component height gaps as small as 2 mils. - Ability to view multiple BGA rows or J-leads to view solder joint profiles - Able to detect the presence of non-metallic contamination such as flux
Inspection of Hidden Solder Connections New Inspection Methods Available 90 prism assisted microscope inspection Cons - Labor intensive - Subjective and requires interpretation - 100% inspection not possible 13
Inspection of Hidden Solder Connections 90 Microscope Visual Inspection Of BGA Joint 14
Inspection of Hidden Solder Connections 90 Microscope Visual Inspection of BGA 3rd Row 15
Inspection of Hidden Solder Connections 90 Microscope Visual Inspection of J-Leads 16
Inspection of Hidden Solder Connections New Inspection Methods Available Real time microfocus x-ray and integrated BGA inspection software Pros - Relatively easy to use - Real time x-ray views observable on a monitor. Can manipulate sample during the inspection process - Can view solder joints in great detail, resolution as great as 0.0001 inches and magnifications can range from 1x to 1300x - Image analysis software program that can eliminate operator judgement with simple pass or fail criteria 17
Inspection of Hidden Solder Connections New Inspection Methods Available Real time microfocus x-ray and integrated BGA inspection software Cons - Labor intensive and not practical for 100% inspection if components obstruct BGA analysis system - BGA analysis system only useful if the x-ray detector is parallel to the PWB. PWB tilt renders the program useless - Unable to detect non-metallic contamination such as flux 18
Inspection of Hidden Solder Connections Real Time Microfocus X-ray Inspection 19
Inspection of Hidden Solder Connections Real Time Microfocus X-ray Inspection 20
Inspection of Hidden Solder Connections Real Time Microfocus X-ray Inspection 21
Inspection of Hidden Solder Connections Real Time Microfocus X-ray with BGA Inspection Software 22
Inspection of Hidden Solder Connections New Inspection Methods Available X-ray laminography Pros - Views solder joints in unobstructed planar (zaxis) sections or “slices” - 100% inspection - Pass/fail criteria can be established prior to inspection and interpretation is not required - Three dimensional solder joint digital reconstruction can be determined for solder volume and characteristics - Inspection process is fast. HP claim of over 10Ksolder joints PWB top and bottom side in less than 10 minutes 23
Inspection of Hidden Solder Connections New Inspection Methods Available X-ray laminography Cons - Initially very labor intensive with programming. 5-7 days of skilled labor for PWB Gerber (graphics) data interface - Resolution of images is poor - Slice size are between 4 to 6 mils, therefore joint cracking could not be detected - Expensive purchase, 540K. Alternative, service is offered at 2K a day - Too much information produced 24
Inspection of Hidden Solder Connections X-ray Laminography Inspection Will Show a Planar “Slice” View of BGA Solder Joints 25
Inspection of Hidden Solder Connections X-ray Laminography Inspection Will Show a Planar “Slice” View of BGA Solder Joints 26
Inspection of Hidden Solder Connections X-ray Laminography Inspection Showing a Planar “Slice” View of BGA Solder Joints 27
Inspection of Hidden Solder Connections 28 Conclusion Process control is of the utmost importance! Visual and real time x-ray examinations should not be used for 100% inspection to verify process control 90 inspection, cross section, and real time x-ray should be used for qualification and failure analysis purposes X-ray laminography can be used for 100% inspection. Is the initial cost worth the volumes of data? Combination of 100% electrical and lot sampling inspection - appropriate method to be determined by the customer
joints. Able to view for BGA solder joint cracks - Able to inspect between components with gaps as tight as 35 mils and component height gaps as small as 2 mils. - Ability to view multiple BGA rows or J-leads to view solder joint profiles - Able to detect the presence of non-metallic contamination such as flux Inspection of Hidden Solder .
paste will be the only option to introduce solder to the joint. The solder paste can be introduced by printing solder on the board or on the part. It is not possible to position a ministencil on a densely assembled board for printing solder paste. The better choice is to print solder on the part and place it on the board using the BGA rework .
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OM-338 PT solder paste Introduction Introducing ALPHA OM-338 PT, a more pin testable variation of the OM-338 lead-free solder paste family. Cookson considered what you need from a lead free solder paste – high yield fine feature printing with a wide process window, excellent reflow yields withFile Size: 1019KB
near-eutectic (63-37 and 60-40) tin-lead solder that has a melting point of approximately 183 oC. Solder Metallurgical Considerations . Before exploring the mechanical properties of room-temperature solder, it is impor-tant to note that molten solder is an extremely good solvent, and readily dissolves metals such as copper and gold that it comes in
Solder You will want rosin core, 60/40 solder. Good solder is a good thing. Bad solder leads to bridging and cold solder joints which can be tough to find.
provider (ISP) connections (including branch connections) No connections Minimal complexity (1–20 connections) Moderate complexity (21–100 connections) Significant complexity (101–200 connections) Substantial complexity ( 200 connections) Unsecured external connections, number of connections not users (e.g., file transfer protocol (FTP),
Line Improving intelligence Automation Labor-saving Improving intelligence ・A perforated pot is used to enable automated solder supply during production. ・Used in combination with solder remaining detection sensor, it can keep the right amount of solder on metal mask. Perforated pot type automatic solder supply
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