DK165153B

DK165153B - MULTIPLE CIRCUIT PLATE WITH RIGID AND FLEXIBLE AREAS

Info

Publication number: DK165153B
Application number: DK359287A
Authority: DK
Inventors: Friedrich-Wilhelm Schlitter
Original assignee: Schoeller & Co Elektronik
Priority date: 1986-07-22
Filing date: 1987-07-10
Publication date: 1992-10-12
Also published as: ATE55532T1; DE3624718C2; DK165153C; DK359287A; DE3624718A1; DK359287D0; EP0254082A3; DE3764215D1; EP0254082B1; EP0254082A2

Abstract

1. A multilayer, locally rigid and locally flexible circuit board with through-connection holes consisting of several individual layers press-moulded with one another, characterized in that it is made up alternately of first single or double layers (2) and second single or double layers (3) of the same non-flexible (rigid) material into which flexible adhesive-coated plastic films (4) free from edge gaps, of equal thickness and with a somewhat larger area than corresponds to the flexible region are inserted in the regions in which the circuit board is intended to be flexible and in that the through-connection holes (7) are only introduced in those regions of the circuit board (1) which, over the cross-section, predominantly consist solely of the material of the rigid single layers (2, 3) and copper.

Description

iin

DK 165153 BDK 165153 B

Opfindelsen angår en flerlaget kredsløbsplade med stive og bøjelige områder og med gennemgående kontakt huller, bestående af flere sammenpressede enkeltlag.The invention relates to a multilayer circuit board with rigid and flexible areas and with through contact holes consisting of several compressed single layers.

For nogle år siden er der i elektronikindustrien 5 indført trykte kredsløb, der har stive og bøjelige områder. Disse kredsløbsplader opbygges af oven på hinanden liggende stive og bøjelige enkeltlag, der ved hjælp af forbindelsesfolie klæbes fast sammen og presses. Der er her tale om ubøjelige, f.eks. glas-10 epoxyharpiks, og bøjelige isolationsbærere, f.eks. poly imidfolie, med enkelt- eller dobbeltsidig kobberbelæg ning, hvori kredsløbsbanerne ætses. De stive lags form fastlægger den stive del af kredsløbspladen, fra hvilken de bøjelige lag fører ud og danner de bøjelige kredsløb-15 sområder, der yderligere forbinder kredsløbets dele med hinanden og danner forbindelsen til ydre opbygninger.A few years ago, in the electronics industry 5 printed circuits were introduced which have rigid and flexible areas. These circuit boards are made up of superposed rigid and flexible single layers, which are bonded together and pressed together by means of connecting foil. These are inexcusable, e.g. glass-epoxy resin, and flexible insulation carriers, e.g. polyimide foil, with single or double-sided copper coating, in which the orbits are etched. The rigid layer shape defines the rigid portion of the circuit board from which the flexible layers extend and form the flexible circuit 15 regions which further connect the circuit parts to each other and form the connection to outer structures.

De bøjelige dele fremstilles ved, at man i disse områder bortbryder de stive yderlag. En sådan fremgangsmåde er f.eks. beskrevet i DE-PS 26 52 212. De bø-20 jelige enkeltlag dækker ved de kendte kredsløbsplader med stive og bøjelige områder af fremstillingsgrunde hele kredsløbspladen, selvom de egentlig kun er nødvendige i den bøjelige del.The flexible parts are made by breaking away the rigid outer layers in these areas. Such a method is e.g. described in DE-PS 26 52 212. The flexible single layers of the known circuit boards with rigid and flexible areas for manufacturing reasons cover the entire circuit board, although they are really only needed in the flexible part.

Før presningen af enkeltlagene til en flerlags-25 kobling fremstilles ledningsbanerne ved ætseteknik på de inderste lag. Kresløbspladerne bliver derpå gennemboret bestemte steder, og hullerne forkobres kemisk og galvanisk. Derved får man en elektrisk forbindelse mellem ledningsbanerne i de forskellige planer. Desuden tjener 30 disse gennemgående kontakthuller til optagelse af tilslutningsbenene på de komponenter, som kredsløbspladen bestykkes med.Prior to pressing the single layers into a multilayer coupling, the conductive paths are prepared by etching technique on the innermost layers. The circular plates are then pierced at specific locations and the holes are chemically and galvanically sealed. This creates an electrical connection between the wiring paths in the different plans. In addition, 30 of these through-contact holes serve to receive the connecting pins on the components with which the circuit board is fitted.

Da ved kendte kredsløbsplader også de stive områder er opbygget af oven på hinanden liggende stive og 35 bøjelige enkeltlag, består hulvæggene lagsvis af forskellige materialer. Frem for alt gennembores også klæbe-Since at known circuit boards, the rigid areas are also made up of superposed rigid and flexible single layers, the hollow walls are layered of different materials. Above all, the adhesive is also pierced

DK 165153 BDK 165153 B

2 middellag, hvorved klæbemiddlet smørres ud over hulvæggen. Rengøringen af væggen før forkobringen er meget kostbar og angriber de forskellige kunststoflag med forskellig styrke således, at der opstår fordybninger 5 i hulvæggen. Også den kemiske forkobring er kostbar, da forskellige stoffer skal aktiveres og metaliseres. Desuden er de termiske udvidelseskofficienter for den bøjelige kunststoffolie og den stive kunststofplade forskellige således, at der ved lodning af kredsløbet 10 kan optræde spændinger og revner, der kan føres til de-laminering.2 medium layers, whereby the adhesive is lubricated beyond the hollow wall. The cleaning of the wall before the dressing is very expensive and attacks the different layers of plastic with different strength so that recesses 5 in the hollow wall are formed. Chemical dressing is also expensive, as different substances must be activated and metalized. In addition, the thermal expansion coefficients for the flexible plastic film and the rigid plastic sheet are different so that when soldering the circuit 10, stresses and cracks that can lead to de-lamination can occur.

Til afhjælpning .af disse vankeligheder er det f.eks. kendt at brænde de bøjelige enkeltlags polyimid og klæbemiddel i hulvæggens område med en laserstråle og 15 udfylde dette område med epoxyharpiks for at opnå et sammenhængende materiale i hulvæggen. Men også denne fremgangsmåde er meget omstændelig og dyr.To remedy these difficulties, it is e.g. known to burn the flexible single-layer polyimide and adhesive in the cavity wall area with a laser beam and fill this epoxy resin region to obtain a coherent material in the cavity wall. But also this approach is very cumbersome and expensive.

Det er derfor opfindelsens formål at tilvejebringe en flerlaget kredsløbsplade, der har stive og bøjeli-20 ge områder og gennemgående kontakthuller, bestående af flere sammenpressede enkeltlag, ved hvilken en omstændelig efterfølgende rensning af hulvæggene bortfalder, og borehullerne alligevel enkelt kan metaliseres og føre til pålidelige kontakter mellem ledningsbanerne.It is therefore an object of the invention to provide a multilayer circuit board having rigid and bendable areas and through contact holes consisting of several compressed single layers, in which a substantial subsequent cleaning of the cavity walls lapses, and yet the boreholes can be easily metallized and lead to reliable contacts between the wiring circuits.

25 Denne opgave løses ifølge opfindelsen ved, at kredsløbspladen er opbygget af stive enkelt- og dobbeltlag og enkelt- eller dobbeltlag af samme ikke bøjelige materiale, i hvilket der i de områder, hvori den senere kredsløbsplade skal være bøjelige er indført bøjelige 30 klæbemiddelovertrukne kunststoffolier uden spalter langs kanterne med samme tykkelse og med noget større omfang, end hvad der svarer til den bøjelige område, og at de gennemgående kontakthuller kun er tilvejebragt i det om råde af lederpladen, der set i tværsnit i hovedsagen kun 35 består af de stive enkeltlags materiale og kobber.This problem is solved according to the invention in that the circuit board is made up of rigid single and double layers and single or double layers of the same non-flexible material, into which flexible adhesive-coated plastic films are introduced in the areas where the later circuit board must be flexible. slits along the edges with the same thickness and to a somewhat greater extent than corresponds to the flexible region, and that the through contact holes are provided only in the area of the conductor plate, seen in cross-section generally only 35 of the rigid single-layer material and copper.

De gennemgående kontakthuller er fortrinsvis anbragt i det område af kredsløbspladen, der udelukkende består af de stive enkeltlags materiale.The through contact holes are preferably located in the region of the circuit board consisting solely of the rigid single-layer material.

DK 165153 BDK 165153 B

33

De indpassede bøjelige kunststoffolierområder må være nogle få millimeter, fortrinsvis 2 til 10 mm, større end det senere bøjelige område, således at der sikres en upåklagelig klæbning af den bøjelige kunststoffolie i 5 det stive område.The fitted flexible plastic film areas must be a few millimeters, preferably 2 to 10 mm, larger than the later flexible area, so that an impeccable adhesion of the flexible plastic film in the rigid area is ensured.

Fremstillingen af disse enkeltlag sker på den måde, at man i såkaldte pre-preg, det vil sige glasmåtter med ikke udhærdet epoxyharpiks, med et værktøj stanser eller skærer en udsparing, der er noget større end 10 kredsløbspladens ønskede bøjelige område. Med samme værktøj udskæres et komplementært stykke af en klæbemid-delovertrukket bøjelig kunststoffolie og indsættes uden spalter langs kanten i pre-preget. Pre-preg og kunststoffolie må her vælges således, at pre-pregets tykkelse 15 i presset tilstand er lig med tykkelsen af den klæbemid-delovertrukne kunststoffolie. På oven- og undersiden af dette forlaminat lægger man derpå en kobberfolie og presser ved tryk og temperatur denne forbindelse til et laminat. Ledningsmønsteret indbrændes derpå ætningste-20 knisk i kobberfolien.The manufacture of these single layers is done in such a way that in so-called pre-marks, ie glass mats with non-cured epoxy resin, a tool is cut or cut into a recess somewhat larger than the desired flexible area of the circuit board. With the same tool, a complementary piece of an adhesive-coated flexible plastic film is cut and inserted without gaps along the edge in the pre-embossed. Pre-embossing and plastic foil must here be selected such that the thickness of the pre-embossing 15 in the pressed state is equal to the thickness of the adhesive-coated plastic foil. On the top and bottom of this laminate, a copper foil is then placed and pressurized at pressure and temperature to a laminate. The conduit pattern is then burnt etch-20 in the copper foil.

Fortrinsvis består det stive materiale af glasfiberforstærket epoxyharpiks.Preferably, the rigid material consists of fiberglass reinforced epoxy resin.

Sammenklæbes enkeltlagene til den flerlagede stive-bøjelige kredsløbsplade - dette sker med pre-preg, 25 glasmåtter med ikke udhærdet epoxyharpiks - har man i kredsløbspladen stive område, hvori boringer til gennemgående kontakt derefter skal tilvejebringes, en forbindelse, der kun består af glasfibre, epoxyharpiks og Cu-folie.If the single layers are glued to the multi-layer rigid flexible circuit board - this is done with pre-stamping, 25 glass mats with non-cured epoxy resin - there is a rigid area in the circuit board in which bores for through contact must then be provided, a compound consisting only of glass fibers, epoxy resin and Cu foil.

30 Disse boringer kan således væsentligt enklere for synes med en gennemgående kontakt end det er tilfældet ved de kendte kredsløbspladeopbygninger. Borehullernes kobberbøsninger er stabile ved efterfølgende lodning og også senere ved indsættelse af det færdige kredsløbskon-35 cept.Thus, these bores can be substantially simpler to appear with a through contact than is the case with the known circuit board structures. The copper bushings of the boreholes are stable upon subsequent brazing and also later upon insertion of the finished circuit concept.

Ved stive-bøjelige lederplader kan de bøjelige lag andrage 20 eller flere planer. Det har vist sig, atIn the case of rigid flexible guide plates, the flexible layers can be 20 or more planes. It has been found that

Claims

A circuit board (1) comprises multiple single layers (2) of rigid material, and single layers (3) of similarly rigid material, wherein flexible plastic sheets (4) as flexible areas of the circuit board are inserted without slots along the edges. The plastic film (4) is coated with an adhesive (5) and, together with the single layer (3), is coated with copper foil (6) for conductive webs. In the rigid region of the circuit board (1), through-holes (7), which are metalized with a copper layer (8) for contacting, are drilled. 25

A multilayer circuit board having rigid and flexible areas and through contact holes, consisting of several compressed single layers, characterized in that it is made up of rigid single or double layers and single or double layers of the same non-flexible material in which: in the areas in which the later 35 circuit board must be flexible, flexible adhesive-coated plastic sheets (4) are inserted without gaps at the edges, of the same thickness and to a somewhat greater extent than the corresponding area, and that the through contact holes (7) are provided only in those areas of the circuit board (1) which, in section in section 5, are generally composed only of the rigid single-layer (2,3) material and copper.

Circuit board according to claim 1, characterized in that the through contact holes (7) are provided in the regions of the circuit board (1), which consist solely of the rigid single-layer (2,3) material.