SAE ARP 1612A-1990 Polyimide Printed Circuit Boards Fabrication of《聚酰亚胺印刷电路板的装配》.pdf

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1、AEROSPACERECOMMENDED PRACTICEARP1612 REV. A Issued 1979-10Revised 1990-01Reaffirmed 2014-08Superseding ARP1612Polyimide Printed Circuit BoardsFabrication ofRATIONALEARP1612A has been reaffirmed to comply with the SAE five-year review policy.1. SCOPE:1.1 This document describes the materials, equipme

2、nt, and processing techniquesutilized in the fabrication of polyimide printed wiring boards. Includedare recommendations for both double-sided and multilayer boards.1.2 The processes described herein are the result of extensive evaluation andmanufacturing experience. These recommendations reflect pr

3、ocedures thathave proven effective in producing low-cost and reliable printed wiringboards.1.3 Safety - Hazardous Materials: Hhile the materials, methods, applications,and processes described or referenced in this document may involve the useof hazardous materials, this document does not address the

4、 hazards that maybe involved in such use. I t 1s the sole responsibility of the user toensure familiarity with the safe and proper use of any hazardous materialsand to take necessary precautionary measures to ensure the health and safetyof all personnel involved (see 9).2. APPLICABLE DOCUMENTS:The f

5、ollowing publications form a part of this document to the extentspecified herein. The latest issue of Aerospace Material Specificationsshall apply. The issue of other documents shall be as specified in AMS 2350.2.1 SAE Publications: Available from SAE, 400 Commonwealth Drive, Warrendale,PA 15096.2.1

6、.1 Aerospace Material Specifications:AMS 2350 Standards and Test MethodsSAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report isentirely voluntary, and its applicability and suitability fo

7、r any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.“SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments andsuggestions.Copyr

8、ight 2014 SAE InternationalAll rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical,photocopying, recording, or otherwise, without the prior written permission of SAE.TO PLACE A DOCUMENT ORDER

9、: Tel: 877-606-7323 (inside USA and Canada) SAE values your input. To provide feedbackTel: +1 724-776970 (outside USA) on this Technical Report, please visitFax: 724-776-0790http:/www.sae.org/technical/standards/ARP1612AEmail: CustomerServicesae.org |_SAE WEB ADDRESS: http:/www.sae.orgSAE INTERNATIO

10、NAL ARP1612A Page 2 of 182.2 U.S. Government Publications: Available from Commanding Officer, NavalPublications and Forms Center, 5801 Tabor Avenue, Philadelphia, PA 19120.2.2.1 Federal Specifications:A-A-113 Tape, Pressure-Sensitive, Adhesive2.2.2 Federal Standards:FED-STD-406 Plastic, Methods of T

11、esting2.2.3 Militarv Specifications:MIL-P-13949MIL-P-13949/10MIL-B-13949/13MIL-F-14256MIL-B-22191Plastic Sheet, Laminated, Metal-Clad (For Printed Wiring),Plastic Sheet, Laminated, Metal-Clad (For Printed HiringBoards), Base Material, Gi Glass Base, Woven, PolyimideResin, Heat Resistant, Copper Clad

12、Plastic Sheet, Laminated, Materials (For Printed WireBoards), Gi Base Material, Glass Fabric Woven, Polyimide,Resin Preimpregnated (B-Stage)Flux, Soldering, Liquid (Rosin Base)Barrier Material, Transparent, Flexible, Heat Sealable.2.2.4 Military Standards:MIL-STD-202MIL-STD-275Test Methods for Elect

13、ronic and Electrical Component PartsPrinted Wiring for Electronic Equipment3. GENERAL:3.1 Polyimide-glass laminates are classified as high-performance materials andoffer significant advantages over conventional laminate materials such asepoxy-glass.3.2 The excellent properties of the polyimide mater

14、ial result from anaddition-type thermosetting reaction. Actually, two chemical reactions takeplace. One is a Micheal-type addition between a low molecular weight diaminecomplex and bis-maleimide type complex at approximately 175C (375F). Thesecond is a cross-linking of bis-maleimide complexes at app

15、roximately 230C(450F).3.3 Polyimide laminates provide solutions to some basic problems that exist withconventional materials. In printed wiring board (PWB) applications theadvantages of polyimide are as follows:3.3.1 Higher glass transition temperature3.3.2 Lower axis expansion coefficients3.3.3 Dec

16、reased resin smearing during drilling3.3.4 Greater delamination resistance and decreased pad lifting during solderingoperationsSAE INTERNATIONAL ARP1612A Page 3 of 183.3.5 Superior resistance to thermal stress damage in thermal shock andtemperature cycling3.3.6 Greater repairabi1ity3.3.7 Lower life

17、cycle costs of electronic assemblies3.4 Polyimide double-sided boards may be processed in an identical manner toconventional epoxy-glass units; however, there are some differences formultilayer boards. Copper-clad polyimide laminates are treated prior tolamination to obtain a cupric oxide finish as

18、opposed to the cuprous oxideutilized for conventional laminates. Slightly higher laminating temperaturesof 175C (350F) and postcuring at 230C (450F) are required for polyimide.Polyimide boards do not require chemical smear removal treatments afterdrilling. Such treatments are commonly used for epoxy

19、 boards.4. PROCESS RECOMMENDATIONS:4.1 Design Considerations: No special design precautions are necessary whenutilizing polyimide boards. The requirements established by MIL-STD-275 forboard design may be utilized for any type of printed wiring board includingpolyimide.4.2 Material Considerations: C

20、opper-clad laminates for double-sided boards and0 multilayer boards should be procured to the requirements of MIL-P-13949/10 oras specified on the drawing. B-stage material should be procured toMIL-P-13949/13. Other materials utilized include commercial grade backermaterial, peanut oil, rosin flux (

21、Type RA or Type RMA, MIL-F-14256), copperplating solution, tin-lead plating solution, resist stripper, cheesecloth,pumice cleaner, touch-up ink (plating resist), etch resist ink, electrolesscopper plating solutions, acid and alkaline cleaning solutions (for example,1% or 25% sulfuric acid, ammonium

22、persulfate solution), 1,1,1trichloroethane (technical grade), dry film resist, and dry film developer,mold release, kraft paper, aluminum oxide paper or slurry, and heat-sealableplastic envelopes.4.3 Equipment Considerations: No special equipment is required to processpolyimide boards. Conventional

23、equipment may be utilized and includes: dryfilm laminator, ultraviolet (UV) exposure unit, dry film developer, vapordegreaser, forced-air oven capable of maintaining a temperature of230C + 5 (450F + 10), copper anodes, oxygen free, high conductivity (OFHC),tin-lead anodes (63/37% tin-lead nominal),

24、plating tanks with racks andclamps as required, deionized water system, resist stripper, etching machine,board scrubber, end mill cutters, carbide drills and router bits, numericallycontrolled (NC) drill, fusing apparatus, silk screens, laminating press,liquid honing machine, various tanks for clean

25、ing/rinsing operations, andsolder bath.4.4 Processing Recommendations: The following practices should be followed toensure the quality of the printed wiring board:4.4.1 Drilled holes shall be of the proper count and at the location specifiedby the part drawing. Holes shall be free of burrs and other

26、 anomalies.SAE INTERNATIONAL ARP1612A Page 4 of 184.4.2 The machine shop and drilling areas shall be clean and orderly.4.4.3 Numerically controlled drills shall be checked at periodic intervals foraccuracy. Drill bits shall be monitored for effective life and discardedor resharpened at specified int

27、ervals.4.4.4 Master patterns shall be to the accuracy specified by the part drawing orother control documentation.4.4.5 Registration shall be verified for double-sided boards by film overlaytechniques or dimensional verification. X-ray techniques may be utilizedto verify the registry of multilayer b

28、oards.4.4.6 At regular intervals, a section of a sample board or test tab shall besolder floated and metallurgically examined for plating integrity, holewall cracking, voids, or other signs of poor quality.4.4.7 The application, exposure, and development of photoresist shall beperformed in an area e

29、quipped with safelights.4.4.8 All plating power supplies, meters, gauges, heaters, etc, shall becalibrated and maintained at regular intervals.4.4.9 All plating anodes shall be examined periodically and replaced whendepleted.4.4.10 Boards shall be thoroughly rinsed after each processing step to ensu

30、recomplete removal of processing solutions and to prevent contamination ofsubsequent solutions.4.4.11 Tape tests using tape conforming to A-A-113 shall be performed to verify0 plating adhesion.4.4.12 All processing solutions shall be prepared and controlled within thelimits specified by their suppli

31、ers.4.4.13 All plating solutions should be monitored using appropriate methods(atomic absorption spectroscopy, wet chemistry) for their essentialelements and maintained within manufacturer-recommended limits.4.4.14 “B“ stage material used for multilayer boards should be stored undercontrolled enviro

32、nmental conditions. When stored at 20C (70F) and 50%relative humidity, “B“ stage materials may be safely used within 3 monthsof their receipt date.4.4.15 Handle boards either with tongs or on the edges with clean, white,lint-free gloves, taking care not to touch or contaminate surfaces to belaminate

33、d, electroplated, or soldered.5. MULTILAYER PRINTED WIRING BOARD FABRICATION CYCLE:Fig. 1 illustrates the typical process steps involved in the fabrication ofpolyimide multilayer boards. The following is an elaboration of these generalprocedures:SAE INTERNATIONAL ARP1612A Page 5 of 185.1 Tooling Req

34、uirements;5.1.1 Master Pattern Film: The film material shall be 0.0075 in 0.0005(0.190 mm 0.013) thick, dimensionally stable polyester film asdescribed in MIL-STD-275. The accuracy of the master pattern shall besuch that the centers of all features (terminal areas, conductors, etc)shall be located w

35、ithin 0.002 in (0.05 mm) radius of the true gridposition established for the layer. For the composite master pattern,the features of all layers shall coincide within 0.003 in (0.08 mm)radius of the true grid position, when measured at 20C 1 (68F 2)and 50% + 5 relative humidity.5.1.2 Drill Tapes: Pun

36、ched tapes suitable for use with numerically controlleddrill tapes may be generated to grid coordinate locations or to thecenters of master pattern terminal areas.5.1.3 Profile Templates/Tapes: Boards may be sized to the proper peripheralconfiguration by a variety of methods. A routing template may

37、befabricated from 0.25 in (6.5 mm) epoxy glass laminate or aluminum.Punched tapes may be prepared for numerically controlled routing machinesor, if volume dictates, blanking dies may be utilized.5.2 Innerlayer Preparation:5.2.1 Prepare Index Holes: The proper type, size, and number of copper-cladinn

38、erlayers are selected and then punched or drilled to form indexing ortooling holes for use in subsequent operations, imaging, lamination, etc.5.2.2 Cleaning: Copper-clad thin laminate innerlayers should be cleaned bydegreasing in trichloroethane or other suitable solvent followed by a combination ov

39、erflow rinse and deionized water. A 30 s immersion in 25%by volume sulfuric acid followed by a combination rinse is used.Scrubbing (machine or pumice) and rinsing to obtain a no-water-breaksurface are required prior to resist application.5.2.3 Resist Application: Two commonly used approaches are scr

40、eening and dryfilm. Because of its photographic precision, dry film is preferred formultilayer fabrication and is described herein.Dry Film Lamination: Cleaned innerlayers are dried for approximately5 min at 95C (200F). Dry film resists of various thicknesses areavailable and are used in roll lamina

41、tors. Processing controls varywith manufacturers but key features are laminating temperature,traverse speed, and roll pressure. Using manufacturer-recommendedsettings, copper-clad innerlayers are laminated with dry film resist.Dry Film Exposure: Dry films are sensitive to UV exposure. An imageis imp

42、arted to the resist-coated innerlayer using the master patternfilm and a UV exposure source. Negative films are utilized which allowhardening of the resist in the clear areas of the film. Typicalcontrols are UV output and exposure time. Useful monitoring devicesinclude UV output meters and exposure

43、step scales.SAE INTERNATIONAL ARP1612A Page 6 of 185.2.3.3 Dry Film Development: The protective cover sheet is removed from theexposed dry-film-coated innerlayers which are then placed inconveyorized developer machines. Dry-film developing solutions may beeither of a solvent or aqueous type. In eith

44、er instance, the developerremoves the unexposed areas of dry film (dark areas of master patternfilm) leaving the copper-clad innerlayer with exposed resist definingall circuit features. Controls in this operation are solutionconcentration, temperature, life, and development time.5.2.4 Touch-up: Afte

45、r development, resist-coated innerlayers are visuallyexamined for anomalies, pin holes, scratches, and breaks, which may betouched up with silkscreen inks formulated to be etch resistant. I f thedegree of touch-up is deemed excessive, the innerlayers may be strippedof resist and reprocessed through

46、the dry film application or scrapped.5.2.5 Etching: A variety of alkaline and acid etchants are used in industry.The purpose of the etching step is to remove unwanted copper from thecopper-clad innerlayer. In the process, the innerlayer is fed into a conveyorized etching machine wherein etching solu

47、tion is sprayed on bothtop and bottom surfaces. The dry-film resist protects the copperconductor areas while the unprotected areas are removed, thereby definingthe circuit image. Most etching machines incorporate internal rinsingand air drying steps after etching. Controls include etchant solutionco

48、ncentration, life, temperature, and conveyor speed.5.2.6 Resist Removal: Depending on the type of resist selected, a solvent oraqueous solution is used to strip the resist from etched innerlayers.This is normally a conveyorized machine operation wherein innerlayers arestripped, rinsed, and air dried

49、. Controls include conveyor speed,stripper solution concentration, life, and temperature. Innerlayersshould be carefully inspected at this point for defects such as brokenconductors, over or under etching, and excess copper. Defects missed atthis stage will show up at the completed board or assembly level as opensor shorts and may result in expensive scrap.5.2.7 Oxide Treatment: The etched copper-clad innerlayers are oxide treated topromote bonding during subsequent lamination. The oxide treatment mustnot be degraded by the 2